WHAT IS JAVAMAIL?
TM
The World’s Leading Java Resource Java COM Volume:4 Issue:10, October1999
Guaranteed Lowest Prices...
From the Editor Holy Wars by Sean Rhody pg. 5
Guest Editorial Presenting Java by Ajit Sagar pg. 7
Straight Talking What an ‘L’ of a Month by Alan Williamson pg. 14 Feature: Ian Moraes E-Java JavaMail Palming Java Framework for developing by Ajit Sagar pg. 28 Internet-based e-mail client applications 8
EJB Home Cover Story: Creating Newsfeeds Using Java Applets John Keogh The Business Make the Internet more relevant, and give Advantage of EJB by Jason Westra pg. 58 your customers better—faster—service 18 CORBA Corner Feature: What Is JavaMail? Rachel Gollub What’s Coming By now you might be asking yourself... 32 in CORBA 3? by Jon Siegel pg. 68 Case History: Enterprise Java at Syracuse University Frank Gates IMHO Distributed applications written in Java using the SIS EJB SIS HTML Web EJB Interface Student Browser Application Interface Server Information Server Calls H Server Manager System T t M le SIS Java OOP Means L or App Interface EJB model to build reliable and scalable systems Server 44 J SIS DB C C Interface alls Server Database OODBMS—Not SIS Server Interface Server by Bruce Scott pg. 94 Widget Factory: A Return to Reflection Jim Crafton RETAILERS PLEASE DISPLAY UNTIL DECEMBER 31, 1999 Adding advanced features to the CodeDocument class à la Borland’s CodeInsight 50 SYS-CON Radio: JavaOne Interviews with Grant Wood & Daniel Berg, and Martin Hardee 64
Product Review: SQL 2000 v7.5 Jim Milbery SYS -CON Pervasive Software’s latest version of its PUBLICATIONS ubiquitous database engine and software development kit 76 BEA www.weblogic.beasys.com
2 OCTOBER 1999
Java COM Protoview www.protoview.com
OCTOBER 1999 3
Java COM Sun Microsystems www.sun.com/service/suned/java2
4 OCTOBER 1999
Java COM FROM THE EDITOR
SEAN RHODY, EDITOR-IN-CHIEF
EDITORIAL ADVISORY BOARD TED COOMBS, BILL DUNLAP, DAVID GEE, MICHEL GERIN, ARTHUR VAN HOFF, JOHN OLSON, GEORGE PAOLINI, KIM POLESE, SEAN RHODY, RICK ROSS, AJIT SAGAR, RICHARD SOLEY, ALAN WILLIAMSON EDITOR-IN-CHIEF: SEAN RHODY EXECUTIVE EDITOR: M’LOU PINKHAM ART DIRECTOR: ALEX BOTERO Holy Wars PRODUCTION EDITOR: CHERYL VAN SISE ASSISTANT EDITOR: NANCY VALENTINE EDITORIAL CONSULTANT: SCOTT DAVISON TECHNICAL EDITOR: BAHADIR KARUV PRODUCT REVIEW EDITOR: ED ZEBROWSKI INDUSTRY NEWS EDITOR: ALAN WILLIAMSON E-COMMERCE EDITOR: AJIT SAGAR WRITERS IN THIS ISSUE JIM CRAFTON, FRANK GATES, RACHEL GOLLUB, JOHN KEOGH, hen I was a teenager, my parents taught me never to argue about JIM MILBERY, IAN MORAES, SEAN RHODY, AJIT SAGAR, sex, politics and religion. Later on I also learned that it’s never a BRUCE SCOTT, JON SIEGEL, JASON WESTRA, ALAN WILLIAMSON good idea to argue with drunks. Now I find myself in the unenvi- SUBSCRIPTIONS able position of having to step into the middle of a “religious” FOR SUBSCRIPTIONS AND REQUESTS FOR BULK ORDERS, Wdebate. PLEASE SEND YOUR LETTERS TO SUBSCRIPTION DEPARTMENT In the July issue of JDJ (Vol. 4, issue 7) we ran a feature story regarding the use of Java with SUBSCRIPTION HOTLINE:800 513-7111 DCOM. It touched off a great deal of debate, both pro and con, concerning the suitability of COVER PRICE: $4.99/ISSUE publishing this article in a magazine like Java Developer’s Journal. DOMESTIC: $49/YR. (12 ISSUES) CANADA/MEXICO: $69/YR. OVERSEAS: BASIC SUBSCRIPTION PRICE PLUS AIRMAIL POSTAGE Arguments against had a couple of themes. One main theme was anything that comes out (U.S. BANKS OR MONEY ORDERS). BACK ISSUES: $12 EACH of Redmond is bad, and there are Java-based alternatives to everything Microsoft. JDJ, as the PUBLISHER,PRESIDENT AND CEO: FUAT A. KIRCAALI standard bearer for Java, should have nothing to do with the “Evil Empire.” A second, some- VICE PRESIDENT,PRODUCTION: JIM MORGAN what more reasonable theme was that Microsoft won’t be supporting Java 2, so their technol- VICE PRESIDENT,MARKETING: CARMEN GONZALEZ ogy is going away. CHIEF FINANCIAL OFFICER : IGNACIO ARELLANO On the pro side, a number of readers felt this article was right on the mark. They’re working ACCOUNTING MANAGER: ELI HOROWITZ CIRCULATION MANAGER. MARY ANN MCBRIDE in an environment where interoperability comes before portability, and this article provided ADVERTISING ACCOUNT MANAGERS: ROBYN FORMA information they needed to get the job done. MEGAN RING Rather than arguing with either of these sides, I thought I’d simply state where JDJ stands JDJSTORE.COM: JACLYN REDMOND on this issue and explain its position. As the editor-in-chief of Java Developer’s Jour- ADVERTISING ASSISTANT: CHRISTINE RUSSELL GRAPHIC DESIGNER: ROBIN GROVES nal, I look for a variety of articles. I look for high-level articles that discuss GRAPHIC DESIGN INTERN: AARATHI VENKATARAMAN the principles of Java programming, technically detailed arti- SYS-CON RADIO EDITOR: CHAD SITLER cles that explain useful Java techniques, and prod- WEBMASTER: ROBERT DIAMOND WEB SERVICES INTERN: DIGANT B. DAVE uct-related ones that discuss the integration of Java CUSTOMER SERVICE: SIAN O’GORMAN with a particular tool. ANN MARIE MILILLO That being said, Java Developer’s Journal will not ONLINE CUSTOMER SERVICE: AMANDA MOSKOWITZ restrict the content of the magazine based on who cre- EDITORIAL OFFICES ates the technology being discussed. We have regular SYS-CON PUBLICATIONS, INC. columns devoted to what I think are the mainstream 39 E. CENTRAL AVE., PEARL RIVER, NY 10965 interests of the language, and they evolve as the times TELEPHONE: 914 735-7300 FAX: 914 735-6547 change and the language grows. I try to mix in a variety of [email protected] topics while sticking to the editorial calendar we set every JAVA DEVELOPER’S JOURNAL (ISSN#1087-6944) is published monthly (12 times a year) for $49.00 by year. My policy is that JDJ will be inclusive rather than SYS-CON Publications, Inc., 39 E. Central Ave., Pearl River, NY 10965-2306. exclusive. When we plan the magazine, we clearly realize Periodicals Postage rates are paid at Pearl River, NY 10965 and additional mailing offices. that every reader won’t read every article. That’s fine. POSTMASTER: Send address changes to: Our goal is to reach a broad audience every month JAVA DEVELOPER’S JOURNAL, SYS-CON Publications, Inc., with enough variety and content that they continue to 39 E. Central Ave., Pearl River, NY 10965-2306. read. ©COPYRIGHT There will be the occasional article regarding Microsoft Copyright © 1999 by SYS-CON Publications, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any technologies. But there won’t be a regular column regarding means, electronic or mechanical, including photocopy or any information storage and Microsoft, nor will we be turning the magazine into Microsoft Java Journal. Our retrieval system, without written permission. For promotional reprints, contact reprint coordinator. SYS-CON Publications, Inc., reserves the right to revise, republish and focus will remain, as always, on all Java technologies. If you’re not interested in topics con- authorize its readers to use the articles submitted for publication. cerning Microsoft, flip past it to the next article. W ORLDWIDE DISTRIBUTION BY I know this may set off another flurry of discussions. I think that’s good – I prefer to see peo- CURTIS CIRCULATION COMPANY ple express their opinions instead of just sitting back and staring at you. If you want to send 739 RIVER ROAD, NEW MILFORD NJ 07646-3048 PHONE: 201 634-7400 me e-mail regarding this, please do so. And please keep reading. Java and Java-based marks are trademarks or registered trademarks of Sun Microsystems, Inc., in the United States and other countries. SYS-CON Publications, Inc., is independent of Sun Microsystems, Inc. All brand and product names used on these pages are trade names, [email protected] service marks or trademarks of their respective companies. AUTHOR BIO SYS -CON Sean Rhody is the editor-in-chief of Java Developer’s Journal. He is also a principal consultant with Computer Sciences Corporation, PUBLICATIONS where he specializes in application architecture – particularly distributed systems.
OCTOBER 1999 5
Java COM NuMega www.compuware.com/numega
6 OCTOBER 1999
Java COM GUEST EDITORIAL PresentingJava WRITTEN BY AJIT SAGAR
n the fast-changing world of Internet-based technologies, perception is every- thing. Is a business solution implemented in a particular technology truly cross- platform? Is it scalable? Is it robust? Is it easy to use? Does it do what it set out to do? Most times the answers to these questions are based on the perception of the Ifunctionality offered by the application. In a distributed application a large part of the burden of providing the perception falls on the designers of the user inter- face. One of Java’s salient features – platform interoperability – is achieved via the perception of user interface portability. I say “perception of portability” because seamless cross-platform portability is paradoxical by its very definition. Let’s take a minute to consider what porting applications between platforms really means. Porting applications between platform A and platform B inherently implies that platforms are incompatible. What this boils down to is that the assembly code generated by an application on platform A will be different from the assembly code generated by the same application on platform B. The executable is different. The combination of hardware, operating system and compilers used by the application is different for the two execution environments. Indeed, it’s this very difference that allows different vendors to tout their value-adds for the industry. And all this is good because it promotes healthy competition. The Ultimate Thin Client Sun Microsystems’ “the network is the computer” message has been consistent right from the beginning. Since Java was introduced in the marketplace, Sun has touted it as the technology that will make this a real- ity. For the network to be the computer, the burden of installing and running the intelligent piece of software applications needs to shift application functionality to tiers that are different from the client user interface tier. In other words, the intelligence and complexity in a solution need to move out of the presentation tier and be buried in different tiers of a distributed application. The presentation tier should be concerned sole- ly with presenting data served up by the next tier. The UI client should be as thin as possible. The catch, however, is that the same application should be able to offer the same functionality via dif- Soft ferent clients. And the world of clients has morphed from dumb vt100 terminals to PCs sitting on every user’s desk to PDAs, cell phones, set-top boxes and pagers. Java offers core technologies that support dis- tributed networking like Jini as well as different flavors of the Java platform for distributing the applica- tion across various tiers of a distributed application. In theory, the same content can be presented across all these devices. As a result, porting the user interface across the various applications should be seam- less. All the devices run Java. As long as the code is pure Java, we should be able to drag class files from a PC and drop them into a 3COM palm. In reality, it’s not as simple as that. Any portable code has to adhere to the least common denomina- Wired tor of features that can be provided across the different display units. This defeats the purpose of the dif- ferent devices, each of which provides unique features in the way it presents the data. This uniqueness manifests itself in the user interface, which is the user’s window into the device. The more realistic approach is to leverage the least common denominator of functionality as much as possible, while keep- ing in mind that parts of the user interface won’t be portable across devices and platforms. The challenge is to decide how much of the functionality needs to be provided in the user interface. The thin-client model may still exist; however, the data served up by the next tier will be different for different devices. Wait a minute.…Does this mean I can keep my user interface device/platform dumb and drive the www.javamessaging.com/ibus user interface from the other tiers of the distributed application? That would be neat. Well, as the saying goes, if it’s too good to be true, it probably is. A big assumption here is that the features offered by a par- ticular UI device or platform can be optimally leveraged by the “server.” This is certainly not true. In fact, the different levels of sophistication of the user interfaces translate to the value-add provided by the ven- dor. The minute you start mixing and matching unique features offered by the device with the least com- mon denominator offered by Java, guess what? Your client just gained weight. Java Clients vs Web Clients Today it behooves Java-based computing solutions to offer several types of clients. One is a Java client (fat client) that takes advantage of specific strengths of an application and presents them in the user interface. This is implemented as a Java application. The second type is a thinner client that uses Java applets to add dynamism to a Web UI on the client. A third type of client is the pure Web client that achieves dynamism via scripting languages. The latter two types have at least one thing in common: they serve up HTML (or XML), i.e., they run in browsers. One of the advantages of the Web clients is that they achieve some level of UI device portability. However, they inherit the issues related to browser portabil- ity. Hence, the burden of UI configuration shifts from Java code to scripting code. The point is that you still have to provide unique implementations to accommodate your environment’s idiosyncrasies. There’s no silver bullet. Designing user interfaces is hard. Creating the right balance of responsibility across the different tiers of distributed applications is hard. However, as long as the appropriate percep- tion is maintained, the end user should be unaware of these complexities. And abstracting complexity is the reason we use software to create business solutions. [email protected] AUTHOR BIO Ajit Sagar, a member of the technical staff at i2 Technologies in Dallas,Texas, holds an MS in computer science and a BS in electrical engineering. He focuses on Web-based e-commerce applications and architectures. Ajit is a Sun-certified Java programmer with nine years of programming experience, including two and a half in Java.
OCTOBER 1999 7
Java COM JDJ FEATURE Framework for developing Internet-based e-mail client applications
WRITTEN BY IAN MORAES
E-mail functionality is an important system requirement in areas such as An e-mail client is used to transfer messages to and from an e-mail e-commerce, customer care, work-flow management and unified messag- server, which is responsible for sending and receiving e-mail messages ing. In addition, some application architectures may need to support not across the Internet. These servers store a user’s messages either perma- only standard mail protocols but also proprietary ones. If you’re charged nently or until retrieved by an e-mail client. with the task of developing an e-mail client application in Java, you have a number of architectural and design options: building your own services layer to support multiple mail protocols, purchasing third-party compo- nents that provide e-mail features or using JavaSoft’s JavaMail framework. This article focuses on the JavaMail framework for developing Inter- net-based e-mail client applications. The JavaMail API shields applica- tion developers from implementation details of specific mail protocols by providing a layer of abstraction designed to support current e-mail standards and any future enhancements. JavaMail increases a develop- er’s productivity by allowing the developer to focus on the business logic of an application rather than on mail protocol implementation. It pro- vides a platform- and protocol-independent means of adding e-mail client features to your applications. JavaMail version 1.1 is a standard Java extension and requires JDK/JRE 1.1.x or higher. Overview of Internet Mail Protocols Before getting into the details of JavaMail, a quick overview of some messaging terms and Internet e-mail protocols (IMAP, POP, SMTP) is in order. A message is described in terms of a header and content. A mes- sage header comprises information such as sender (from), recipient (to), and message ID (a unique message identifier). A message’s content is the actual message body and can comprise multiple parts in the form of text and attachments, as shown in Figure 1. FIGURE 1 Structure of an e-mail message
8 OCTOBER 1999
Java COM JavaMail Architecture Now that you have a basic understanding of Internet mail terms, we can begin to discuss the JavaMail architecture. As shown in Figure 3, the archi- tecture can be described in terms of three main layers. JavaMail’s layered architecture allows clients to use the JavaMail API with different message access protocols (POP3, IMAP4) and message transport protocols (SMTP). The top layer is the application layer that uses the JavaMail API. The second layer is the JavaMail API that defines a set of abstract classes and interfaces for supporting e-mail client functionality. This is the layer that frees a developer from having to deal with protocol-specific complexi- ties. JavaMail provides concrete subclasses of these abstract classes for Internet mail. The JavaMail API layer depends on concrete implementa- tions of protocols. The implementation layer forms the third layer of the JavaMail archi- tecture. Since JavaMail is protocol independent, it’s up to service providers to implement specific message access and message transfer protocols. Service provider implementations play a role similar to that of JDBC drivers. A provider registry allows service providers to register their protocol implementations to be used by JavaMail APIs. The JavaMail Web site has more information on third-party service providers. JavaBeans Activation Framework JavaMail interacts with message content through an intermediate layer called the JavaBeans Activation Framework (JAF), part of the Glas- gow specification (a future release of the JavaBeans component model specification). In terms of dealing with e-mail messages, JAF provides a uniform way of determining the type of a message’s content and encap- sulating access to it. The JAF is implemented as a standard Java exten- sion. Sun provides a royalty-free implementation of JAF that requires JDK 1.1.x or higher. JAF is used to get and set a message’s text and attachments. JavaMail provides convenient methods to interact with JAF. For example, MimeMessage’s setText() method can be used to set a string as a mes- sage’s content with a MIME type of “text/plain.” Another example is MimeMessage’s getContent() method, which returns a message’s con- tent as a Java object by invoking methods on JAF’s DataHandler class. JAF can also be used to view e-mail attachments such as a text file (.txt) or an image (.gif) by instantiating a JavaBean that supports a par- ticular command (e.g., view) on a specific type of message content. As
To develop an e-mail client you need to deal with protocols for send- ing and receiving messages. As shown in Figure 2, the common protocol for sending Internet e-mail messages is SMTP (Simple Mail Transfer Pro- tocol). The original SMTP specification limited messages to a certain line length and allowed only 7-bit ASCII characters. The MIME (Multipur- pose Internet Mail Extensions) specification builds on SMTP by remov- ing the maximum line length for messages and allowing new types of content (e.g., images, binary files) to be included in e-mail messages. The MIME specification overcomes these limitations by defining addi- tional fields in a message header to describe new types of content and message structure. MIME defines the content-type header to specify the type and subtype of message content. For example, a message with an HTML attachment would have a content-type header set to “text/html”. FIGURE 2 Protocols for sending and getting e-mail messages SMTP and MIME are typically used together to send Internet e-mail messages. Two types of protocols are used to retrieve messages from Internet mail servers: POP3 (Post Office Protocol 3) and IMAP4 (Internet Mes- sage Access Protocol 4). Although POP3 is more widely used than IMAP4, the latter has a number of advantages. First, IMAP supports multiple folders on a remote mail server whereas POP3 supports only the Inbox folder. Second, IMAP supports message status flags (e.g., indi- cates whether a message has been previously seen); POP3 doesn’t. These types of protocol features are important considerations in designing your application. JavaMail provides implementations of SMTP, IMAP4 and POP3. For more information on these Internet mail protocols, you can consult the pertinent RFCs. FIGURE 3 Overview of JavaMail architecture
OCTOBER 1999 9
Java COM CLASS NAME DESCRIPTION // Setting mail user properties SESSION This javax.mail class represents a mail session and serves as mailProperties = new Properties(); the main entry point for the JavaMail API. The Session class mailProperties.put("mail.transport.protocol", "smtp"); controls access to the Store and Transport objects. mailProperties.put("mail.smtp.host", "someSmtpHost");
TRANSPORT This javax.mail class represents a transport agent that sends a The Session object is a factory for Store and Transport objects. A Ses- message to its recipients using a specific message transfer sion and Store object can be obtained as follows: protocol. Transport is implemented by a service provider. // Get a Session object STORE This javax.mail class defines a message store (a database and Session session = Session.getDefaultInstance(mailProperties, null); an access protocol) for a set of message folders. Folder objects // Get a Store object are accessed through a Store object. Store is implemented by a Store store = session.getStore(); service provider. One issue to consider as you design the application architecture of FOLDER This javax.mail class comprises messages and subfolders in a your e-mail client is the dependency between your business layer and treelike structure. It also defines methods to retrieve and delete JavaMail. To reduce tight coupling between your application’s business messages. Message objects are accessed through a Folder layer and the JavaMail subsystem, the Facade design pattern can be object. Folder is implemented by a service provider. used. For example, mail user configuration can be passed into a Facade (singleton) to assemble the appropriate JavaMail objects (Session, Trans- MESSAGE This javax.mail class models an e-mail message. A Message port and Store) and perform any other initialization (e.g., security). As a object interacts with its content using JAF. The javax.mail.inter- result, dependencies between your business layer classes and the Java- net.MimeMessage class extends Message to represent a MIME Mail subsystem are reduced, and your business layer can use a simpler message. Message is implemented by a service provider. interface such as MailFacade.configure(Properties p). A use case pertaining to e-mail server connectivity is support for “dis- ADDRESS This javax.mail class models an e-mail address. The connected e-mail operation,” which involves maintaining e-mail mes- javax.mail.internet.InternetAddress class extends Address to sage stores on both the remote server and a local client, performing support Internet e-mail addresses. operations on both stores, and then being able to synchronize these two stores. JavaSoft’s IMAP provider implements interfaces that can be used DATAHANDLER Message content is represented as a javax.activation.DataHand- to support disconnected operation. ler class that wraps around the actual data. The DataHandler At the time of this writing, secure messaging (e.g., support for class provides an interface to the JAF. S/MIME) is currently missing from JavaMail. S/MIME builds security on top of MIME to provide secure electronic messaging for Internet mail in TABLE 1 Important classes and interfaces when using JavaMail the form of message authentication and data security. Although not available in JavaMail, it can be obtained from a third party. The JavaMail shown below, the JAF DataSource object, which encapsulates the attach- Web site has more information on this and other third-party Web sites. ment, is used to create a DataHandler object. The DataHandler object uses a CommandInfo object to retrieve the pertinent JavaBean that can Sending e-Mail Messages be used to perform a specific operation on an attachment. The JavaBean Once a mail session has been established, an e-mail message can be component can then be added to a frame, as shown in the code snippet created and sent. First, a MimeMessage object needs to be constructed. below. Currently, reference implementations of JAF-aware JavaBeans are Then, as shown below, the message object is initialized with the recipi- available to view text, GIF and JPEG files. CommandInfo, DataSource ent’s e-mail address(es), the subject of the message and the message and DataHandler are all JAF classes. text. The message is then sent using the Transport object.
// file name represents the attachment // Create new message FileDataSource attachFds = new FileDataSource(attachmentFilename); Message msg = new MimeMessage(session); DataHandler dh = new DataHandler(attachFds); // Initialize the message CommandInfo viewCi = dh.getCommand("view"); msg.setFrom(new InternetAddress(senderEmailAddress)); Frame attachmentWindow = new Frame("View Attachment"); msg.setRecipients(Message.RecipientType.TO,InternetAddress.parse // add the bean to view the attachment to the main window (recipientEmail,false)); attachmentWindow.add((Component)dh.getBean(viewCi)); msg.setSubject(subject); msg.setText(messageText); Examples Using JavaMail Transport.send(msg); You now have a basic overview of the JavaMail architecture and JAF so we can discuss the main JavaMail classes and methods needed to sup- JavaMail can also be used for developing mail-enabled servlets (e.g., port an e-mail client. Table 1 describes some fundamental JavaMail using a browser to send e-mail to a support center). An important archi- classes. tectural consideration is reuse of the mail functionality in your business To illustrate the use of JavaMail in an e-mail client application, I’ll layer by both Web and Java clients. This can be accomplished by using a consider four major use cases: configuring a connection to e-mail layered architecture and appropriate design patterns. For example, a servers, sending a message, getting messages from an e-mail server and simple mail Facade that shields a client from the JavaMail API can be deleting messages. used by both a Java client and a servlet to send an e-mail messge; a client needs to provide the view and controller components (Model-View- Configuring a Connection to an e-Mail Server Controller design pattern) of the application. Before you can send or receive messages from your mail server, you When sending messages, users assume that e-mail clients support need to establish a mail session between the mail client and the remote address books, but JavaMail currently does not. However, the JavaMail mail servers. Mail user properties are used to initiate a connection to API doesn’t preclude you from developing your own mechanism (e.g., mail servers. The Session class can manage the mail user properties used using XML – for implementing local address books or using JNDI to by the JavaMail API. access an LDAP-enabled server for global address book features).
10 OCTOBER 1999
Java COM EnterpriseSoft www.enterprisesoft.com
OCTOBER 1999 11
Java COM Getting e-Mail Messages applications for use with low bit-rate clients using POP (which doesn’t After you’ve successfully established a mail session, an e-mail client maintain flags to indicate unread messages), downloading all messages can retrieve your e-mail messages. To retrieve your messages use the each time becomes a performance issue. Thus you may need an algo- Session object to obtain a Store object, which can be used to obtain the rithm that uses provider-specific methods to prevent a redownload of Inbox folder, as shown below. messages. Depending on your requirements, other algorithms may be needed. // Opening the Inbox Folder Each of these different download algorithms can be encapsulated as store = session.getStore(); Strategy classes (Strategy design pattern) that share a common interface. store.connect(); A Strategy Factory can return strategy objects that can be used to down- Folder folder = store.getFolder("INBOX"); load messages, depending on particular user configurations. This folder.open(Folder.READ_WRITE); approach allows you to switch from one download algorithm to another, depending After a folder has been successfully opened, ‘‘ on the user configuration, and avoid having it’s used to get message totals and the mes- to use protocol-specific conditional state- sages, as illustrated in the following code snip- ments. For more information on the Strategy pet. JavaMail is a and other design patterns, consult Design Patterns by Gamma et al. (1995). // Getting message totals and messages When you download messages from a from a folder server, a feature that’s available in some pop- int totalMessages = folder.getMessage- relatively new ular e-mail clients is an Inbox Assistant to Count(); process incoming messages (e.g., delete mes- Message[] msgs = folder.getMessages(); sages based on user-specified rules). Current- ly, JavaMail doesn’t provide direct support for Note that the Message objects returned from framework that features such as automated message filtering. the getMessages() method call are designed to be lightweight objects. For example, the Mes- Deleting e-Mail Messages sage objects returned could comprise only A standard use case for e-mail clients is message header details. Retrieval of the actual will inevitably deleting a message. Using JavaMail, deleting message content is deferred until the message messages from a folder is a simple two-step content is actually used. Thus the getMes- process. First, messages are marked for sages() method isn’t designed to be a resource- deletion. Those messages that have been intensive operation. continue marked are then deleted from a folder by A typical e-mail client first displays a sum- either explicitly invoking a Folder’s mary of messages in the form of header details expunge() method or closing a folder with such as sender (from), recipients (to), subject the expunge parameter of the close() and sent date. A summary line for each mes- to mature method set to true. sage can be obtained as follows. // Set delete message flag Address[] from = msgs[i].getFrom(); message.setFlag(Flags.Flag.DELETED, Address[] to = msgs[i].getRecipients(Mes- and evolve true); sage.RecipientType.TO; // Delete marked messages from folder String subject = msgs[i].getSubject(); folder.close(true); Date d = msgs[i].getSentDate(); After viewing the message summary, a user typically decides to view’’ Conclusion the actual message content in the form of text and/or attachments. Now This short introduction should help you use JavaMail 1.1 to develop an e- we’re ready to get a message’s content, which can be retrieved in the mail client application. JavaMail is a relatively new framework that will form of an object. The retrieved object depends on the type of content. inevitably continue to mature and evolve. Nevertheless, it can be used to rapid- If the content is a message with multiple attachments, a Multipart object ly develop an e-mail client application using a higher-level API without having (a container of BodyPart objects) is returned. If the Part’s content is text, to perform the arduous task of implementing specific mail protocols and then a simple String object is returned. To retrieve a message’s content, developing an architectural infrastructure to support multiple protocols. You you can invoke Part’s getContent() method, as illustrated below. Note can obtain more information on JavaMail/JAF, including sample programs for that Part is an interface implemented by Message and BodyPart classes. sending and retrieving e-mail messages, from the references listed below.
Object o = part.getContent(); Resources If (o instanceof String) { JavaMail: www.javasoft.com/products/javamail/index.html // content is text JavaBeans Activation Framework: } else if (o instanceof Multipart) { www.javasoft.com/beans/glasgow/jaf.html // recursively iterate over container's contents to retrieve attachments Gamma, E., Helm, R., Johnson, R., and Vlissides, J. (1995). } else if (o instanceof Message) { Design Patterns: Elements of Reusable Object-Oriented Software. // message content could be a message itself } AUTHOR BIO Ian Moraes, Ph.D., is a principal engineer at Glenayre Electronics, where he works on the architecture and You’ve now seen how messages are retrieved using JavaMail. If your design of a unified messaging system. Ian has developed client/server systems for the telecommunications application supports both IMAP and POP, you may need to develop dif- and financial services industries. ferent algorithms to download messages, depending on your particular use case and performance requirements. For example, when developing [email protected]
12 OCTOBER 1999
Java COM Unify www.ewavecommerce.com
OCTOBER 1999 13
Java COM STRAIGHT TALKING What an ‘L’of a month! From IV drips and rejected usernames/passwords to…Neil Diamond (?)
hat a month this one has been! Life has this wonderful way of letting you know that no matter what you’re feeling at any given moment, you just can’t predict what’s going to be round the next corner. One of our chaps is at this pre- WRITTEN BY cise moment lying flat on his back, bored senseless, in our ALANWILLIAMSON Wlocal hospital. It all began last weekend. Murray was having a quiet weekend – Java is the underlying software running which is in contrast to a bad memory ref- not doing much, just relaxing. He climbs within a medical monitoring tool. Now, erence in C/C++ that has the potential of into bed on Sunday evening with a wee given that, let’s pretend something goes bombing the program completely. nagging pain in his stomach. By the time wrong. Since this is all make-believe so If anyone has had the experience of Monday morning rolled round he was far, let’s pretend that a java.io.IOExcep- writing mission-critical health applica- feeling a pain never before felt and the tion is thrown for some reason. I don’t tions, I’d love to hear from you. Join our doctor was called immediately. Doctor know…the port reading the sensor from mailing list and let us know just how then called an ambulance, and within five the patient goes wrong. What do you do? much testing goes into this kind of soft- hours Murray was on an operating table What is the worst-case scenario here? ware. I think I’m scared to know this having his ruptured appendix removed. Well, death, I suspect. information in case it’s not as much as I In a very short space of time poor When you think about it, how many would expect. So, fingers crossed. Murray’s world was completely turned of us would have faith enough in our round. All plans he had, all plans we own code to have our lives depend on it? One L had, are on hold for a number of weeks I know there are a number of classes I’ve This month we also ran into a funny until he’s back on his feet again. Poor written that I’d probably risk somebody wee problem that had us chasing our bugger. I don’t envy his position at all, else’s life on, but not my own! tails for at least a couple of days. I’m complete with a drip into his arm. I have more than confident this is a situation to admit to being a bit of a wimp with many of you have had happen at some regard to this sort of thing. Needles and point in your development. Let me take blood don’t really work for me. I’m the you through the tale. sort of person that can nearly pass out One of our clients, who will remain watching “ER,” and as far as I’m con- nameless, had this bright idea of using cerned nurses who have to deal with this the password anjelia1, with a “one” at sort of thing daily are pure angels. And if the end as opposed to a lowercase “L.” all that isn’t enough, no e-mail access! Not a problem, we figured, and never The man is in hell! I think we should gave it much thought until we started to spearhead a campaign to have hospitals move the end system from our develop- linked up to the Internet with at least ment server to their production server. 64K of bandwidth to each bed. For some reason we couldn’t get our One thing about hospitals and the database connection up and running. It whole general health thing, it certainly kept saying “incorrect username and focuses your mind. With us all going in Okay, we jest here. But when you think password combination.” The problem on a daily basis we are more thankful for about how Java is structured, there’s real- was further augmented by the fact that our own state of health, and now even ly so much to go wrong that’s not even we had no control over the database as it more determined to try and maintain a your responsibility. We all assume the was running on an external server. We general state of good health. However, virtual machine we entrust our byte- couldn’t even change the username and we’ve been having some rather interest- codes to has been coded to a very high password to one that we knew. ing conversations regarding all the soft- standard and will run 100%. Of course it’s So we had to work with the one we ware that must be running throughout not 100%, but we as developers have to were given. But we were convinced we the hospital. In the ward in which Mur- make that assumption – otherwise we’re had the right username/password ray is laid up is a vast array of devices merely building a house of cards. entered. Then one of us joked that the that are continually flashing, reading, That said, I believe I’d be more com- “1” looked very like a lowercase “L.” monitoring, alerting, whatever. fortable with, say, Java as opposed to a Well, in actual fact, with the font choice Let’s imagine that the world is the C/C++ alternative. Many other languages in our telnet window and the font of the utopia we Java developers believe it will aren’t quite as tolerant of mistakes as Java. normal text in Netscape, they rendered be one day in the fact that Java has The exception handling is very good, con- to be pixel for pixel exactly the same. We found a home in many of these applica- sidering that many applications can still had no idea what the “L” we had typed tion areas. Assume for the moment that run after an error has been reported, in the configuration file.
14 OCTOBER 1999
Java COM VisiComp www.visicomp.com
OCTOBER 1999 15
Java COM S T R A I G H T T A L K I N G Needless to say, we changed the con- as a handy set of utility classes. We into maintaining the JServ mailing lists. figuration file very, very carefully, ensur- looked into offerings from other sites We’ve come across many in the corpo- ing that our hands typed a “one” as trying to do the same thing, but felt rate world who feel really uncomfort- opposed to an “L.” Well, after restarting many of them lacked proper manage- able with the lack of official support for the server, the whole thing burst into life ment. So at this precise moment we’re using the likes of Apache and other and the problem was solved. looking to form our own version of this. open-source software. But the speed at It may seem obvious now, but at the For more information on this and other which Jon answers questions puts a lot time it was an eventuality we didn’t even threads of discussion, come and join of companies that charge for this level of think about. So the moral of the tale is our mailing list. The good news is that support to shame. So, Jon, on behalf of that from this point forward we have getting off the bugger is just as easy as the developer community, thank you, banned all use of ones and zeros from all getting on to it. sir, for a job well done. usernames and passwords. Drastic I To join send an e-mail to listserv@list- admit, but a decision I feel comfortable serv.n-ary.com with subscribe straight_- Book Review in enforcing. talking-l in the body of the e-mail. From This month I haven’t had time to read I’m running out of space at this point there you’ll get instructions on how to any books, which is truly a shame. If so I’ll just have to remember to tell you participate on the list. anyone has any good references to next time about a really bizarre books they think I should read, please e- encounter one of our chaps had with a Salute of the Month mail me. Would love to hear from you. AUTHOR BIO Microsoft lawyer. If you knew how This month I’d like to take my hat off to But as one door closes, another opens. Alan Williamson is CEO remote we really are, you’ll think it even three people who, together, do a fine This month we’ve discovered the won- of n-ary (consulting) Ltd, more bizarre. Next month, I promise. piece of work that all of us in the Java der of Neil Diamond. The man is a saint! the first pure Java community benefit from. I’m talking I never appreciated what I dismissed as company in the UK. A Mailing List about the core team behind the Apache his middle-aged music before, but after Java consultancy company As you know, each month I plug the JServ project, which enables the Apache hearing one of his compilation albums I with offices in Scotland, mailing list that this column spawned. Web server to run Java Servlets: Jon realized I hadn’t known just how much England and Australia, Well, some good news on this front. No, Stevens, Stefano Mazzocchi and Pierpao- stuff he wrote that’s been covered by they specialize solely in this isn’t the last plug, but in fact a lo Fumagalli. They not only make Apache many other artists. So I’m on a journey Java at the server side. report of something good being born attractive to use, they’re also pretty cool of Diamond-discovery and who knows Alan is the author of two from the whole discussion list. We’ve guys. We haven’t come up against any where that will lead me to. Java Servlet books and been discussing many interesting top- combination like Apache + JServ that On that note, I have to tottle off now contributed to the Servlet ics, and an idea that’s been bouncing makes running servlets so easy, without and get on with some real work….Sweet API. He can be reached around was that of an open-source Java compromising performance. Caroline… bom-bom-bom! at [email protected] library. This is where a core set of Jon “read-the-faq” Stevens deserves a (www.n-ary.com). libraries would be held that would serve special mention for the effort he puts [email protected]
SlangSoft www.slangsoft.com
16 OCTOBER 1999
Java COM Segue www.segue.com/ads/corba
OCTOBER 1999 17
Java COM WRITTEN BY JOHN KEOGH
he conventional way to present up-to-date information is to keep it on your Web The Code The source code for the applet, contained in the file newsfeed.java, is site or a Web site you have some access to or control over so you can modify the less than 300 lines, yet it contains all the functionality necessary to cre- ate a simple newsfeed. It uses Java 1.0 event handling to keep the event information as needed.This article describes a way to create newsfeeds using Java handling simple and to work with older browsers. To compile it using a JDK 1.1 compiler, you’ll need to use deprecation: applets so that the applet can be embedded anywhere in any page,and the applet javac newsfeed.java –deprecation. The included packages and classes are needed for painting (awt.*), distributor can keep the presented information up to date by modifying informa- storing information in a vector (Vector), parsing the information returned from the server (StringTokenizer), networking (net.*), tion on the site.Ways to extend the ability of the applet using CGI programming input/output classes and required exceptions (io.*), and working with dates (Date). are also examined.This solves problems for theaters,clubs and other organizations The integer variables that have global scope within the class – speed, iHeight, iTimesThrough and iCurrentPosition – store the speed of the that want their information on many pages but want to maintain it in just one thread and the font height and keep track of the number of times the retrieved news has been presented and the current position in the list of spot.Establishments that want to distribute information about sales and events, news items. The initial value of iTimesThrough, 11, is explained in the paint() method. The Thread variable, called newsthread, is used to and,of course,news organizations,can also benefit from distributing newsfeeds. implement the Runnable interface. An Image object is used for the background image. The String objects – strCurrentString and This article also discusses a way to ensure that the information isn’t loaded from strCurrentURL – are used to store the current news item and the asso- ciated URL. The boolean bCalledFromRun, if true, increments iCurrent- cache (anticaching). Position when paint() is called. The Vector veInformation is used to con- tain the news items retrieved from the server. Conceptually, this applet connects back to the server and retrieves infor- The class extends Applet and can be run either in a browser or in Tmation – from a flat file or a script – as a stream of bytes that are cast to chars AppletViewer. Implementing Runnable permits the class to spawn and and appended to a StringBuffer. The toString() method in StringBuffer is run in its own thread. To implement the Runnable interface, we need to called, and the resulting string is parsed to create a Vector containing the implement start(), stop(), and run() methods (discussed below). news and any other information returned by the server. When you want to Unlike most applets, newsfeed doesn’t override init(); all the initial- use the applet as a newsfeed, you can permit other sites to embed the applet ization is done in the initialize() method. This method is called from in their pages (using the CODEBASE=“URL” attribute, with the URL being paint() the first time that paint() is called and every 10 times thereafter the directory on your server where the class files are, just as you can embed to refresh the news. an image loaded from another server in another page, as shown in Figure 1). The initialize() method is the key method of the applet. The Date The applet then connects back to the server from which it was downloaded object that’s created is used to get the current time in milliseconds and gets the information, irrespective of the page in which it’s embedded. (stored in lUnique), which is used to circumvent caching (anticaching is
18 OCTOBER 1999
Java COM getCodeBase().getHost() and creates a URL with the returned host and the path “/news/news.txt”. If the applet was downloaded from www.lith- ic.com and you used the path “/news/news.txt”, the URL would be http://www.lithic.com/news/news.txt. The “?”+lUnique circumvents caching. You can, of course, use other paths and file names, but the file must be a publicly accessible ASCII file in the correct format. The last three examples of URL are scripts, discussed later in this article.
OCTOBER 1999 19
Java COM The start(), stop() and run() methods are used to implement the runnable interface. A Thread object called newsthread is instantiated and started in the start() method. The run() method is called repeatedly, and the thread is paused for speed milliseconds; then repaint() is called. The stop() method is called when the applet stops. To update the news in real time, just upload a new flat file or change FIGURE 2 Applet background FIGURE 3 Applet background the data in the database if you’re using a database with a script. Flat files for a company for a club can also be changed by using CGI scripts that allow an authenticated user to modify, delete or add to the contents of the flat file. The next time are news items. After the image is loaded, the variable that tracks the the applet accesses the flat file or script, it’ll get the current information number of times the new items have been presented is set to 0. (sometimes flat files are cached by the server, but in our experience this To simplify working with the information returned from the server, hasn’t been a problem). the vectorize() method creates a Vector from it. The two parameters passed in are the String to parse and the String on which to tokenize it. If Working with CGI Scripts vs Flat Files the String to parse ended with the token used to parse, we’d end up with Whether using a flat file, a CGI script that uses a flat file for data or a a final piece of zero length. To avoid this, if the string ends with the parse CGI script that uses a DSN and a database, the applet expects the data to character, it’s pulled off. Because most files or streams of bytes sent via a be presented in a certain format: server are punctuated by a
20 OCTOBER 1999
Java COM KL Group www.klgroup.com/swingsuite
OCTOBER 1999 21
Java COM Conclusion Listing 1: newsfeed.java The newsfeed is easy to set up and distribute, but if you have some dif- // newsfeed.java a class for creating a newsfeed ficulty, here are some things to check. // includes • In the newsfeed.java, did you choose the right string for the URL (for example, if you have a news.txt in a feed directory, make sure you cre- import java.awt.*; import java.util.Vector; ate a string that points at /feed/news.txt)? import java.util.StringTokenizer; • Check if the URL creation code was changed to url=new URL(str) (this import java.net.*; is indicated in comments in the code). import java.io.*; • Did you upload the news file in ASCII mode and the class files in bina- import java.util.Date; ry mode? //class that implements a simple newsfeed • You should use the Perl script only if you have some experience with public class newsfeed extends java.applet.Applet Perl. implements Runnable • You may want to remove the ?=code after the .txt if you’re using a flat { file and having problems. int speed=2000, iHeight=0, iTimesThrough=11, iCurrentPosition; Thread newsthread; This implementation of a newsfeed, though limited, created a very Image image; small class file that displays news, responds to button clicks when there String strCurrentURL, strCurrentString; is a link associated with a news event, and circumvents caching. Many boolean bCalledFromRun=false; improvements are possible: adding more colors, offsets, speed, audio Vector veInformation; clips and so forth. Additionally, double buffering would offer smoother // called from paint when needed, don't want to graphics. The applet offers a functional framework in a small package. // call from init, because we need a graphics Using a newsfeed solves many of the problems associated with the // object for this static nature of Web pages and solves access issues. For example, a doc- private void initialize(Graphics g) ument on a CD-ROM could present current information (provided that { String strType=getParameter("type"); the person reading the HTML document in which the newsfeed was if(strType==null) embedded was attached to the Internet). Used correctly, newsfeeds strType="ls"; based on the applet described in this article can be a way to make the net more relevant, provide better service to your customers and substantial- //a date is used to prevent caching Date date=new Date(); ly decrease the time it takes to disseminate information. long lUnique=date.getTime();
AUTHOR BIO iHeight=g.getFontMetrics().getHeight()+2; John Keogh is president of Lithic Software Corporation, an Internet software and services company. He has a background in computer science, chemistry and technical writing. John programs in C, C++, Java, Perl, SQL g.setColor(Color.black); g.drawString("Getting current news...", 45, and several other languages.You can visit his Web site at www.Lithic.com/. iHeight);
[email protected] strCurrentURL="."; iCurrentPosition=0; Receive the //first one for use on your own system, with //appletviewer, second third, fourth, or fifth “JDJ Digital Edition” //for use on the Web, depending on if you use FREE! when you... //a flat file in a directory called news, or a //script in a cgi-local or cgi-bin directory, and //how the script parses the query string String str="news.txt"; //String str="http://"+getCodeBase().getHost()+ // "/news/news.txt?"+lUnique; //String str="http://"+getCodeBase().getHost()+ // "/cgi-local/newsfeed.pl?"+ // strType+iUnique; //String str="http://"+getCodeBase().getHost()+ // "/cgi-bin/newsfeed.pl?"+ // strType+lUnique; //String str="http://"+getCodeBase().getHost()+ // "/cgi-bin/newsfeed.pl?type="+ // strType+"&time="+lUnique+ // "&docbase="+getDocbase();
//a url object is created, then a stream is created //to retrieve the content of the url URL url=null; String strContent=""; 99 try $ { year/12 issues //first one for use on your own system, with //AppletViewer, second for use on the Web 39 url=new URL(getCodeBase(), str); JavaDevelopersJournal.com //url=new URL(str); } catch(MalformedURLException m){return;} 1800-513-7111 try subscribe online for faster service { StringBuffer sb=new String- [email protected] Buffer("");
22 OCTOBER 1999
Java COM BlueSky www.blueskysoftware.com
OCTOBER 1999 23
Java COM InputStream is=url.openStream(); public void paint(Graphics g) DataInputStream dis=new DataIn- { //clear putStream(is); Dimension d=this.size(); Dimension d=this.size(); while (true) g.setColor(Color.white); { //the first time through, and each g.fillRect(0, 0, d.width, try{sb.append((char)dis.read- //ten thereafter, get the news d.height); Byte());} if(iTimesThrough>10) catch(EOFException f){break;} { //draw the background image } //clear this if(image!=null) strContent=sb.toString(); g.setColor(Color.white); g.drawImage(image, 0, 0, this); } g.fillRect(0, 0, d.width, d.height); catch(IOException e){return;} g.setColor(Color.red); initialize(g); //after the contents of the url are } g.drawString(strCurrentString, 45, //retrieved, they are parsed to iHeight); //create a Vector which contains //clear if(strCurrentURL.compareTo(".")!=0) //the information g.setColor(Color.white); showStatus(strCurrentURL); veInformation=vectorize(strContent, ""); g.fillRect(0, 0, d.width, d.height); else showStatus("No Link"); //get the background image, then //draw the background image this.stop(); //remove it if(image!=null) return true; String strImage=(String)veInforma- g.drawImage(image, 0, 0, this); } tion.elementAt(0); veInformation.removeElementAt(0); //get the current text and url, //if the mouse exits the applet, //then draw the text //repaint the text blue and start //load the image, if there is one String strTemp=(String)veInforma- //running again. Clear the status if(strImage.compareTo(".")!=0) tion.elementAt(iCurrentPosition); public boolean mouseExit(Event e, int image=getImage(getCodeBase(), strCurrentURL=strTemp.substring(0, x, int y) strImage); strTemp.indexOf(" ")); { strCurrentString=strTemp.sub- Graphics g=this.getGraphics(); iTimesThrough=0; string(strTemp.indexOf(" ")+1); g.setColor(Color.blue); } g.setColor(Color.blue); g.drawString(strCurrentString, 45, g.drawString(strCurrentString, 45, iHeight); //parses the returned information iHeight); this.start(); //based on 24 OCTOBER 1999 Java COM Sybase www.sybase.com OCTOBER 1999 25 Java COM lshttp://www.lithic.com/onlinesystems/in MAIN: { dex.html Check out LSC Online Systems { print(""); $file="cginews.txt"; print(" no news currently avail- tmhttp://www.toastmasters.org/ Toastmas- $querystring=$ENV{"QUERY_STRING"} ; able"); ters main page is more useful than ever print("Content-type: text/html"); } tmhttp://www.lithic.com/tm/tm.html Grand if($querystring) } { Junction Clubs now have a page $query=substr($querystring, 0, 2); &PrintNews($file, $query); Listing 5: cginews.txt Listing 3: newsfeed.html } lslithic.gif } tmtm.gif
Instantiation www.instantiations.com
26 OCTOBER 1999
Java COM PointBase www.pointbase.com/devlic/jdj
OCTOBER 1999 27
Java COM E-JAVA
Palming Java Cross-device portability ’d like to start this month’s article with some of my impres- sions of JavaOne ’99. Last year was far more exciting with promises of new magic kits and potions handed out in abun- dance.This year there was a definite touch of reality in the air with less sleight of hand and more live rabbits actually jumping out of the hat and onto the stage.The smoke and WRITTEN BY mirrors were still there, but there was some substance AJIT SAGAR Ibehind them. The “real” feel to JavaOne is due to ment on a software platform that can be same, the vehicle for conveying it was the fact that Sun seems to have finally embedded in these consumer devices is radically different. It seems that the ulti- gotten its story straight in terms of what its footprint, which must be extremely mate device for taking Java to the streets “ubiquitous” really means. When you small. One of the main features of the has been identified as 3COM’s PalmPi- look at WORA (write once, run any- J2ME is its tiny footprint. lot. I see this as a smart move. Sun is tap- where), the promise still holds true. Sun has been giving away the Java ping into the large market the Palm has However, what is it that you end up run- language and associated APIs for free, and will have in the future. ning anywhere? Is it the same Java? I but that doesn’t bring the money in. My take on the alliance is that the don’t know about you, but I feel more With the acceptance of Java as the com- Palm has given Java the home it was des- comfortable knowing that the Java that’s mon platform for consumer devices, perately looking for. Even though Java going to run on my pager isn’t the same Sun has a foot in the door of an extreme- was finding applicability in other con- one that runs my banking application. ly large market. Now they can really start sumer devices, it wasn’t making a signif- The Java platform has been segregated collecting on their investment in Java. icant impact. Over the last two years Sun into three platform editions. Sun’s Web has introduced tailored JVM technology site explains their strategy: “Recognizing Java 2 Micro Edition to serve products in the consumer and that ‘one size doesn't fit all,’ Sun has J2ME bundles the APIs for software embedded markets. These include Per- regrouped its innovative Java technolo- development in the consumer space. sonal Java technology targeted at screen gies into three editions: Micro (J2ME), This includes devices ranging from phones, high-end PDAs and set-top Standard (J2SE) and Enterprise (J2EE).” rings, smart cards and pagers to more boxes, and Java Card technology target- A detailed discussion on the purpose intelligent PDAs like the PalmPilot and ed at smart cards, the Java Ring, I-But- of each edition of the Java platform is cell phones – all the way up to appli- ton, etc., which have yet to get the buy- best left for another time. This month I’d ances with set-top boxes such as TVs. in from consumer-oriented vendors. A like to focus on some of the application With J2ME Java provides a complete more intelligent device was needed that areas of the Java 2 Micro Edition – specif- end-to-end solution for creating net- would do a lot more than allow you to ically, the 3Com PalmPilot consumer worked products and applications for brew your coffee. The Palm comes with a device and how it leverages the features the consumer and embedded markets. large set of application suites, so it of the Java platform. We’ll also look at The J2ME framework further segre- already has the beginnings of industry why the PalmPilot may be the killer gates the major types of consumer verticals stemming from it. application Java has been looking for. devices by grouping them into a limited number of categories with varying levels KVM – The Palm’s Keys to “Ubiquity” Consumer Devices and Java of built-in intelligence. To help content The relationship between the Palm Java started out as a language for developers, each category has a profile; and Java is going to be one of symbiosis. embedded consumer devices, specifical- it’s defined in the form of a specification The market for one feeds the market for ly for set-top boxes like the toaster and of the minimum set of APIs useful for a the other. To increase its lead in the mar- the television. Over the last four years, particular product, and a specification ketplace, specifically against the CE, the Java has made its impact on the enter- of the Java Virtual Machine functions Palm needs to have an open, nonpropri- prise as the language and platform of required to support those APIs. etary interface for working with other choice for designing distributed, enter- devices. This is made possible by Sun’s prise-level business solutions. Indeed, The PalmPilot – Java’s Saving Grace? Java KVM, which forms the core of J2ME. Java is one of the key enablers for the Back to JavaOne – another obvious The KVM is so named because its size rapidly evolving areas of e-commerce. thing was the change in what Sun was is measured in the tens of kilobytes, One of these areas is the world of peddling this year. Last year it was all around 80–100K. It fits in the tiniest intelligent consumer devices where the about network computers. The NC was handheld devices such as pagers, and intelligence is built into the network. going to be the ultimate consumer-end needs to run on an underlying operating The various devices, such as cell phones, device; everything else would reside on system. In the case of the PalmPilot, this pagers and smart cards, need to be able the network. Another thing I noted – operating system is the PalmOS. The to access the network via a common there wasn’t much talk about rings and KVM is a new Java runtime environment computing platform. The J2ME edition buttons. built from the ground up to make an of Java attempts to provide such an envi- This year, though the message – “The extremely lean implementation of the ronment. The most practical require- Network Is the Computer” – was still the JVM.
28 OCTOBER 1999
Java COM New Atlanta www.newatlanta.com/
OCTOBER 1999 29
Java COM E - J A V A The KVM has been developed by Sun them for the services they offer. The Cross-Device Portability in collaboration with other industry part- Palm will be another such device. With It looks like Java and the Palm have ners, such as service providers. These Jini, the Palm can become truly net- entered into a marriage made in heaven. partners are crucial for making sure the work-enabled and leverage services However, fidelity isn’t necessarily a pre- KVM can truly enable mobile network from a plethora of computers, appli- condition for this relationship. One of devices such as digital cellular phones, ances, enterprise-level systems and Java’s greatest claims to fame is its porta- pagers, mainstream personal digital consumer devices. bility. In the consumer device segment, assistants, low-end analog set-top boxes i.e., using J2ME, it translates to portabil- and small retail payment terminals. Putting It in the Commerce Perspective ity across these devices. The Palm is one The KVM binary code will be available J2ME and the KVM help solidify Sun’s of the many consumer devices that will in prerelease form for 3Com’s Palm II vision of “providing the dot in the .com” support an edition of the Java VM. and Palm V. Sun anticipates that a wide networking world. This ties in with the e- Indeed, several other consumer devices range of wireless devices containing the business model of service-based busi- already support Java on their operating KVM will become available early in 2000. nesses on the Web. The current commerce systems. Basically, Java allows them to market is rapidly shifting from a product- speak the same lingo. PalmOS – Java’s Gateway to the Consumer? based paradigm to a service-based one. As mentioned above, the KVM needs This means that instead of installing soft- Trading Places an OS to run on. The PalmOS software will ware products, organizations are shifting The market for e-business is expected AUTHOR BIO serve as a primary reference platform for toward a model in which the products are to grow to over a trillion dollars by 2003. Ajit Sagar, a member of application development using KVM. Sun hosted at remote locations and their ser- My contention is that in about 10 years the technical staff at and 3COM are collaborating to provide an vices are available across the network. All the only kind of commerce that will exist i2Technologies in Dallas, end-to-end solution for delivering con- the necessary software can be down- in this world is e-commerce. Program- Texas, holds an MS in tent and Java applications to Palm com- loaded across the Internet. ming languages come and go, but the computer science and a puting platform devices via Sun’s software This isn’t a reality yet, but Java enables applications they give birth to last a long BS in electrical engineer- products. The next level of integration will this business model because of its rich time. Devices like the Palm are introduc- ing. He focuses on Web- involve joining Java with 3Com’s Palm.net support for networking, dynamic nature ing completely new suites of applica- based e-commerce service, the recently announced wireless and portability. The Palm is one of the tions that will help define the end-user applications and service for the Palm VIII. many devices that can play in this area. interface in the world of e-commerce. architectures. Ajit is a Once the underlying infrastructure is in The combination of the Palm and Java Sun-certified Java Rubbing the Magic Lamp… place, these devices can play more sub- creates a powerful, exciting platform programmer with nine Another enabler for this new world of stantial roles in e-commerce transac- that’s revolutionizing the way e-busi- years of programming consumer devices is Java’s Jini technolo- tions. For example, the Palm can act as a ness is conducted today. experience, including two gy, which allows a device on the network kiosk for purchasing goods, quoting ser- and a half in Java. to discover other devices and query vices, auctioning products and so on. [email protected]
Quick Steam www.quickstream.com
30 OCTOBER 1999
Java COM Tidestone www.tidestone.com
OCTOBER 1999 31
Java COM JDJ FEATURE By now you might be asking yourself the question...
WRITTEN BY RACHEL GOLLUB
JavaMail is a set of abstract classes that create a framework for send- central location, where the user can either log in and read it directly or ing, receiving and handling e-mail, along with implementations of those use a client/server mail protocol to read it remotely. IMAP is designed to classes. The package Sun provides contains implementations of IMAP keep mail on a remote server and let the user interact with it there, while and SMTP, allowing you to get started immediately on sending and POP3 is designed to forward a user’s mail to a single machine, where the receiving mail. They also provide a separate POP3 implementation that user can go offline and read it, if necessary. In general, people with slow I’ll describe below. The framework makes it easy to create your own connections (dial-up or otherwise) tend to use POP3 because they can cross-platform mail application without an in-depth knowledge of e- connect and download their mail without having to keep the connection mail. Methods and classes that open afterwards. People with fast allow you to access mail folders, connections and multiple ma- download messages, send mes- chines usually use IMAP so they sages with attachments and filter can read mail from whichever mail are included. machine they happen to be on JavaMail has a number of uses in without losing access to the mail personal and Enterprise-level pro- they read elsewhere. In the fol- gramming. It can be used to create lowing examples, you will need a personal mail filters, simple mailing POP3. lists and customized personal mail applications, as well as to add full e- How Do I Get Started? mail capabilities to an Enterprise First, you’ll need the JDK (I use application or create a full-fledged 1.2 in this article), JavaMail pack- e-mail client. A number of products age and the JavaBeans Activation currently available are built for or Framework extension (JAF). JAF is around JavaMail; many are listed on a standard extension that provides the JavaMail Third Party Product a way to identify and correctly page (http://java.sun.com/prod- process unknown data. You can ucts/javamail/Third_Party.html). download each from the Java Web Several companies have written site. JDK 1.2 (also known as the marketing applications that use Java 2 SDK) is at http://java. JavaMail to send customized mail sun.com/products/jdk/1.2/, and to groups of contacts, and many JavaMail and JAF are at http:/ companies have written new e-mail /java.sun.com/products/ clients using JavaMail and its exten- javamail/index.html. Follow the sions. installation instructions given on the download pages, and install the Background packages. JavaMail comes with a Knowing a little about what e-mail is and how it is sent and received is number of examples in the demo directory, many of which are easy to use helpful in creating e-mail applications. E-mail protocols are, in the most immediately or can be modified for specific situations. basic sense, a way of transferring data from one machine to another, A simple example is msgsendsample.java. This sends a simple mes- possibly going through several other machines along the way. SMTP has sage (included in the example) to an e-mail address provided by the user. existed, essentially in its current state, since the early 1980s, and POP To use this, go to the demo directory and compile msgsendsample.java. and IMAP aren’t much younger. The preceding is a very basic introduc- Then, on the command line, type: tion to these protocols; see “Where to get more information” for more information. java msgsendsample
32 OCTOBER 1999
Java COM Fierano www.fiorano.com
OCTOBER 1999 33
Java COM address, but a look at the full headers will show the real source. The false Mail. This is important to remember. If you ever install JavaMail as part at the end indicates that you don’t want to see the debug information; of a product, be sure to include this directory in your product package. change that to true for a look at what the example is doing. The complete To add the POP3 provider, create a file called javamail.providers with SMTP connection dialog will be printed out, as well as some debug the following line in it: information for the example. A look at the source shows how this example works: protocol=pop3; type=store; class=com.sun.mail.pop3.POP3Store;
Properties props = new Properties(); Then jar the directories again (jar cvf mail.jar *), back up the old props.put("mail.smtp.host", host); mail.jar and move the new mail.jar into place. You now have a POP3 provider added to your provider list. JavaMail needs the mail host property set to determine where the The POP3 example is included here as Listing 2. Download and com- SMTP server is located. If it’s on your local machine, the send can hap- pile the program – you’ll need a POP3 mail server to test it. The example pen locally. Otherwise it will automatically connect to the server takes parameters
This section creates the actual message object and fills in the to, from, Session lSession = Session.getDefaultInstance(lProperties, null); subject, date and content. There are also options to set the reply to, con- tent and content type, and other header information. Since this is a As in the last example, the session is started with no security. This time MIME – Multipurpose Internet Mail Extensions – message, it can have it’s started with the system properties instead of an empty Properties several parts, none of which have to be plain text. You may want to set a object. section to HTML or add an attachment. You can set a DataHandler (in the JDK) using setDataHandler() in MimeMessage to handle nontext Store store = null; parts. This is a simple one-part text message, so you can use the setText() Folder folder = null; method instead. try { store = lSession.getStore(protocol); Transport.send(msg); }
This actually sends the message, using SMTP. If the send fails, it will This part gets the store type for the given protocol (POP3). Store is an throw exceptions based on the problem with the send. For example, try abstract class that models a message store. This allows connections to sending to a nonexistent address for example, (“rachelfoo”). You’ll see a various types of actual message stores with no loss of generality. SendFailedException, with some details about the address that failed. With a few changes you can modify this example to send mail pro- store.connect(host, user, password); grammatically. Changing the
A More Complex Code Sample folder = store.getDefaultFolder(); The next example will read and optionally delete messages from a ... POP3 server. The first step is to download and install a POP3 provider. folder = folder.getFolder("INBOX"); The example uses Sun’s POP3 provider. Follow the directions from the JavaMail page at Sun (listed above) to download and unzip the package, This initializes the folder with the standard default mailbox, indicated and set your classpath correctly. Since you may want to use other by the key word “INBOX”. In this context INBOX stands for “primary fold- providers later, you need to add this provider to your provider list. To do er for this user on this server” – it will vary by protocol, server and user. this, create a new directory, copy the mail.jar file into that directory and unjar it (jar xvf mail.jar). You’ll see several directories, including a META- folder.open(Folder.READ_WRITE); INF directory, which generally contains information about the jar file ... that includes it, but in this case also contains information critical to Java- Message[] messages = folder.getMessages();
34 OCTOBER 1999
Java COM ObjectSwitch www.objectswitch.com/giotto45
OCTOBER 1999 35
Java COM Here the folder is opened and the messages are downloaded. This interested in using: getMatchingHeaders() instead of getAllHeaders(). includes their headers and all parts of the message (in the case of MIME The rest of the example recursively divides the message into parts and messages). This doesn’t remove them from the server; it just copies them prints each part. This example could easily be expanded to filter out into memory. messages with selected subjects or messages from particular addresses. It could store the messages in a database or to a file. In all, JavaMail gives if (delete) you powerful tools to filter and manipulate e-mail messages with very messages[i].setFlag(Flags.Flag.DELETED, true); simple code. ... folder.close(true); For More Information store.close(); 1. JavaMail home page: http://java.sun.com/products/javamail/index.html 2. RFC 821 (SMTP specification: http://info.internet.isi.edu/in- Flags indicate the status of the message in the folder. Here each down- notes/rfc/files/rfc821.txt loaded message is marked deleted, and when the folder is closed the 3. IMAP, POP3: ftp://ftp.cac.washington.edu/mail/imap.vs.pop “true” flag indicates that all deleted messages should be removed. For anything not covered in these sources, a simple Net search will probably find what you need. E-mail is a frequently discussed topic on for (Enumeration e = pPart.getAllHeaders(); e.hasMoreElements(); ) the Net, and there are FAQs and articles everywhere. Good luck! { Header header = (Header) e.nextElement(); AUTHOR BIO System.out.println(header.getName() + ": " + header.getValue()); Rachel Gollub, founder of SilentQ Software Company, learned Java as a JavaSoft engineer from 1995 to } 1997, and has worked at several start-ups since then. She writes articles and gives presentations on Java and related subjects. This section gets each of the header lines from the message and prints them out. You could change this part to print out only the headers you’re [email protected]
(message.custom, for (int i = 0; Listing 1 message.text)); i < validSent.length; /* i++) * SendMessage.java Transport.send(msg); System.out.println */ } catch (MessagingException mex) { (" "+valid- System.out.println Sent[i]); import java.util.*; ("\n--Exception handling in " + } import java.io.*; "msgsendsample.java"); } import javax.mail.*; } import javax.mail.internet.*; mex.printStackTrace(); System.out.println(); import javax.activation.*; System.out.println(); } while ((ex = ((MessagingEx- Exception ex = mex; ception)ex) /** do { .getNextException()) != * This is copied almost directly from if (ex instanceof null); * msgsendsample.java, by Max Spivak, SendFailedException) { return false; * with changes by Rachel Gollub SendFailedException sfex = } * ([email protected]). More details (SendFailedException)ex; return true; * are available in the accompanying Address[] invalid = } * article. sfex.getInvalidAddresses(); */ if (invalid != null) { /** public class SendMessage { System.out.println * This is a simple replace method. (" ** Invalid Addresses"); It public boolean send(MessageObject message) { if (invalid != null) { * searches for the keywords, and //create some properties and get for (int i = 0; uses //the default Session i < invalid.length; i++) * a StringBuffer to replace them. Properties props = new Proper- System.out.println * ties(); (" " + * @param macros The keywords and props.put("mail.smtp.host", mes- invalid[i]); values. sage.host); } * @param message The message to // Uncomment this to debug } change. //props.put("mail.debug", args[3]); Address[] validUnsent = * sfex.getValidUnsentAddress- * @return The changed message. Session session = es(); */ Session.getDefaultInstance(props, if (validUnsent != null) { public String replace (Hashtable null); System.out.println macros, session.setDebug(false); // true to (" ** ValidUnsent String mes- debug Addresses"); sage) { if (validUnsent != null) { for (Enumeration e = macros.keys(); try { for (int i = 0; e.hasMoreElements(); ) { // create a message i < int index = 0; Message msg = new MimeMessage(ses- validUnsent.length; i++) String key = (String) e.nextEle- sion); System.out.println ment(); msg.setFrom (" String value = (String) (new InternetAddress(mes- "+validUnsent[i]); macros.get(key); sage.from)); } while ((index = InternetAddress[] address = } message.indexOf(key, index)) {new InternetAddress(mes- Address[] validSent = !=-1) { sage.to)}; sfex.getValidSentAddress- StringBuffer text = msg.setRecipients es(); new StringBuffer(message); (Message.RecipientType.TO, if (validSent != null) { message = text.replace(index, address); System.out.println index + key.length(), value) msg.setSubject(message.subject); (" ** ValidSent .toString(); msg.setSentDate(new Date()); Addresses"); index += value.length(); msg.setText(replace if (validSent != null) { }
36 OCTOBER 1999
Java COM Cerebellum www.cerebellumsoft.com
OCTOBER 1999 37
Java COM } variables. return message; */ } /* public MailPrinter(String pUser, } * MessageObject.java String pPassword, String pHost, */ String pDelete) { user = pUser; /* import java.util.Hashtable; password = pPassword; * MakeMessage.java host = pHost; */ /** if * This class holds message informa- (pDelete.toLowerCase().equals("true")) import java.util.Hashtable; tion. delete = true; * } /** * @author Rachel Gollub (rachel@silen- * This is a test class that creates tq.com) /** some */ * The run() method makes a mailbox * MessageObjects to send with SendMes- public class MessageObject { connection sage. String to; * every five minutes to check for * String from; mail. * @author Rachel Gollub (rachel@silen- String host; */ tq.com) String subject; public void run() { */ String text; while (true) { public class MakeMessage { Hashtable custom; doStore(); } try { /** Thread.sleep(300000); * The main method initializes the Listing 2 } catch (Exception e) { objects /* e.printStackTrace(); * and sends them. * MailPrinter.java } */ */ } public static void main(String } args[]) { import java.io.BufferedReader; import java.io.InputStream; public void doStore() { SendMessage message = new SendMes- import java.io.InputStreamReader; Properties lProperties = sage(); System.getProperties(); MessageObject object = import java.util.Enumeration; makeObject("[email protected]", import java.util.Properties; Session lSession = "Rachel", "choco- Session.getDefaultInstance late"); import javax.mail.Address; (lProperties, null); message.send(object); import javax.mail.FetchProfile; // Set debug here object = makeObject("jeremy@silen- import javax.mail.Flags; lSession.setDebug(false); tq.com", import javax.mail.Flags.Flag; "Jeremy", import javax.mail.Folder; Store store = null; "chicken"); import javax.mail.Header; Folder folder = null; message.send(object); import javax.mail.Message; try { object = makeObject("miriam@silen- import javax.mail.Multipart; store = lSession.getStore(proto- tq.com", import javax.mail.Part; col); "Miriam", import javax.mail.Session; } catch (Exception e) { "milk"); import javax.mail.Store; System.out.println message.send(object); ("Couldn't get store from pro- } /** tocol."); * This class monitors a given mailbox e.printStackTrace(); /** every 5 } * This creates the actual MessageOb- * minutes, and prints the contents to // Connect ject stdout. try { * for each recipient, filling it * It will also optionally delete mes- if (host != null || user != null with sages it || password != null) * standard and custom values. * reads. More detailed comments are store.connect */ provided in (host, user, password); public static MessageObject makeObject * the accompanying article. else (String to, String name, String * store.connect(); food) { * @author Rachel Gollub (rachel@silen- } catch (Exception e) { MessageObject object = new Mes- tq.com) System.out.println("Unable to sageObject(); */ connect."); Hashtable macros = new Hashtable(); public class MailPrinter extends Thread e.printStackTrace(); macros.put("$firstname", name); { } macros.put("$favoritefood", food); public static void main(String // Open the Folder object.to = to; args[]) { if (folder == null) object.custom = macros; // These args are
38 OCTOBER 1999
Java COM Object International www.oi.com
OCTOBER 1999 39
Java COM } ure out the } catch (Exception e) { * message type, and recursively System.out.println if (folder != null) { sends ("Couldn't access parts."); folder.open(Folder.READ_WRITE); * multi-part parts through the fil- e.printStackTrace(); int lTotalMessages = ter. } folder.getMessageCount(); * } else if (o instanceof Message) { * @param part The message part. return filter((Part)o); if (lTotalMessages == 0) { * } else if (o instanceof Input- System.out.println("Empty folder"); * @return True iff successful. Stream) { folder.close(false); */ BufferedReader lReader = new folder = null; public boolean filter(Part part) { BufferedReader store.close(); (new InputStreamReader((InputStream) } Object o = null; o)); } int c; } catch (Exception e) { try { StringBuffer lBuffer = new e.printStackTrace(); for (Enumeration e = part.getAll- StringBuffer(); } Headers(); try { e.hasMoreElements(); ) { while ((c = lReader.read()) != -1) // Get and process messages Header header = lBuffer.append((char) c); if (folder != null) { (Header) e.nextElement(); lReader.close(); try { System.out.println(header.get- } catch (Exception e) { Message[] messages = Name() + System.out.println("Read error."); folder.getMessages(); ": " + header.getValue()); e.printStackTrace(); } } for (int i = 0; System.out.println("\n"); i < messages.length; i++) { o = part.getContent(); System.out.println(lBuffer.toString()); if (filter(messages[i])) { } catch (Exception e) { return true; if (delete) System.out.println } messages[i].setFlag ("Couldn't get content."); return false; (Flags.Flag.DELETED, true); return false; } } } } if (o instanceof String) { } folder.close(true); String lMessage = (String) o; store.close(); System.out.println(lMessage); } catch (Exception e) { return true; e.printStackTrace(); } else if (o instanceof Multipart) } { } Multipart lPart = (Multipart)o; } try { int count = lPart.getCount(); /** for (int i = 0; i < count; i++) * The filter() method tries to fig- return filter(lPart.getBodyPart(i));
When Bruce Scott (cofounder of ORACLE) started PointBase, Inc. he chose Java Developer’s Journal as PointBase’s exclusive advertising partner!
We Know How to Create Success Stories!
Java COM VSI www.vsi.com/breeze
OCTOBER 1999 41
Java COM SHOP ONLINE AT JDJSTORE.COM FOR BEST PRICES OR CALL YOUR ORDER IN AT 1-888-303-JAVA TakeTake aa looklook atat ourour specialsspecials thisthis month!month!
EASTLAND DATA SYTEMS Internet Shopping with Java Shopping Cart …Described as the most progressive and interac- tive form of shopping on the web today…This IBM’s Java Applet provides a com- plete user interface package for VisualAge for Java 2.0 Internet Shopping Web Sites. Using Java technology we pro- Enterprise Edition duce a drag-and-drop shopping $ 99 user interface that is fun and JDJStore.com Price . . 2,498 easy to use, encouraging shop- COMPARE... pers instead of frustrating them $ 00 loper’s ve jo Programmer’s Paradise Price ...... 2,499 e u d r A n with confusing controls that are hard to follow. And a V
$ 00 A l J JDJ
Beyond.com Price ...... 2,525 Readers’ the easier it is to shop, the more you sell.
World class CHOICE $ 99 loper’s AWARD AWARD ve jo ...... 294 e u d r A n V a
A l J JDJ
Readers’
World class CHOICE AWARD AWARD Hybrid Shopping Cart This Java Applet provides a complete user inter- face package for Internet Shopping Web Sites. A "Hybrid" is defined as an offspring of two varieties. A blending of the best features from our CGI and Java shopping products, we SYMANTEC’s BORLAND’s took the most powerful aspects of Java technology; real-time, Visual Café JBuilder 3 on-screen updating and com- Professional Edition Professional New User putational capabilities. And combined those with the most $ 99 $ 99 desirable features of our CGI JDJStore.com Price . . 258 JDJStore.com Price . . 499 loper’s ve jo e u COMPARE... d r COMPARE... shopping Cart, namely it's flexibility and compati- A n V a
A l $ 95 J JDJ $ 99
bility with web designers with artistic talent. Programmer’s Paradise Price ...... Readers’ Programmer’s Paradise Price ...... 259 545
World class $ 99 CHOICE $ 75 AWARD AWARD $ 99 ...... 294 Beyond.com Price...... Beyond.com Price...... 299 548 CGI Shopping Cart SYBASE SYBASE The Shopping Cart automates the Shopping Process to make shopping on your site intuitive, PowerBuilder Enterprise v.7 PowerJ Enterprise straight forward, and enjoyable! It's one of the most affordable Shopping Carts because it was designed for Release 7.0 of the market-leading enterprise PowerJ provides a true end-to-end solution for small businesses. Specifically development environment offers significant building sophisticated Internet applications, for entrepreneurs who are test- productivity enhancements and broad support for exploiting the benefits of HTML, Java clients, and ing the Internet waters, and Web-based component standards. With the new delivering powerful Java server-side components. can't or don't want to make HTML DataWindow, you can deploy to all major Web PowerJ not only offers powerful database large investments into bells and browsers. Tight integration in both development and capabilities -- it also integrates seamlessly with whistles for their site. But simply want to make deployment with EAServer offers highly competitive Sybase Enterprise Application Server, enabling shopping on their site easy for the customer. reliability, availability, and scalability (RAS) for PB enterprise-class applications from creation, to ...... $29499 applications developed for the Web. testing and debugging, to deployment.
$ 99 Guaranteed Best Prices PowerBuilder Enterprise v.7 ...... $278999 PowerJ ...... 304 JDJ Store Guarantees the Best Prices. If you see any of our products listed anywhere at a PROTOVIEW BLUE SKY SOFTWARE lower price, we'll match that price and still bring you the same quality service. JSuite v2.5 RoboHELP Office 2000 Terms of offer: • Offer good through November 30, 1999 • Only applicable to pricing on current JSuite, a low priced bundle of four of the industry's leading JavaBeans component Now You Can Create a High-Quality Custom Java- versions of software products. It includes: CalendarJ: Calendar Display Component. DataTableJ: The Help System with RoboHELP Office. RoboHELP Office • August issue prices only Fastest Grid Component On The Net! Tree- provides a user-friendly WYSIWYG authoring environ- • Offer does not apply towards errors in ViewJ: Feature-Rich TreeView Component. ment for creating JavaHelp. RoboHELP guides you competitors' printed prices WinJ Component Library: A Series Of UI through the process so you can create a great Java- • Subject to same terms and conditions Components. Help system - with point-and-click and drag-and- loper’s drop ease. Now you can create JavaHelploper’s systems as ve jo ve jo e u e u The JSuite comes with both JDKd 1.02 r easily as you create WinHelp, Microsoftd HTMLr Help, Prices subject to change. n n A A V a V a
A l A l Not responsible for typographical errors. Classes and JAR files with supportJ JDJ for Java and WebHelp (cross platform Help)J JDJ from the same
2 and JDK 1.1.x Source Code is also available. source product - all with RoboHELP Office. World class World class AWARD AWARD Attention Java Vendors: To include your product in JDJStore.com, JSuite v2.5 ...... . ...... $79499 RoboHELP Office 2000 . . . . . . ...... $88899 please contact [email protected] ORDER TODAY! 888-303-JAVA
Java COM SHOP ONLINE AT JDJSTORE.COM FOR BEST PRICES OR CALL YOUR ORDER IN AT 1-888-303-JAVA GUARANTEED BUY THOUSANDS BEST PRICES 0F PRODUCTS AT FOR ALL YOUR JAVA-RELATED GUARANTEED SOFTWARE loper’s ve jo e u d r A n V a
A l J JDJ NEEDS Readers’
World class CHOICE LOWEST PRICES! AWARD AWARD SYBASE KL GROUP INSTANTIATIONS SQL Anywhere Studio JProbe Suite JOVE Starter Kit
JProbe Profiler is the most powerful tool available The JOVE Super Optimizing Deployment JRun is the industry-leading tool for deploy- for finding and eliminating performance bottle- Environment lets you create and deploy the ing server-side Java. JRun is an easy-to-use necks in your Java code. JProbe Coverage makes world's fastest, most efficient Java applica- Web server “plugin” that allows you to it easy to locate individual lines of untested code tions. JOVE combines aggressive whole- deploy Java Servlets and JavaServer Pages. and reports exactly how much of your Java code program and object-oriented optimization Servlets form the foundation for sophisticat- has been tested. JProbe Threadalyzer lets you technologies, native compilation, and a scaleable runtime architecture ed server-side application development. Java pinpoint the cause of stalls and and deadlocks in and deployment environment. The runtime system includes state-of-the- servlets are platform independent, easy to your Java applications and makes it easy to predict race conditions that can art multithreaded generational garbage collection, native multi-threading, develop, fast to deploy, and cost-effective to corrupt application data. low overhead polymorphism, and a number of other incredible technolo- loper’s eloper’s ve jo maintain. v jo e u gy pieces. As a result of all this technology, JOVE enables the creation of e u d r d r n n A JProbe Profiler w/StandardA Support a V V a very high performance, robust executable files for the deployment of A l A l J JDJ J $ 99 JDJ $ 99 very large, complex Java applications. SQL Anywhere Studio 1 user price ...... (includes JProbe Memory Debugger) ...... 335 Readers’ 464 $ 99 $ 99 World class CHOICE SQL Anywhere Studio 5 user price ...... 849 JProbe Suite w/Standard Support . .AWARD ...... . . . . . 934 AWARD $ 99 JOVE Super Optimizing Deployment Environment. . . . 4494 ORACLE IBM INSTALLSHIELD JDeveloper Suite Personal Edition WebSphere Application Server InstallShield Java Edtion 2.5
InstallShield Java Edition 2.5 is the Oracle JDeveloper Suite 2.0 provides a complete Java development Whether it's business integration, Web self-service or e-commerce, IBM powerful tool developers require to environment for developing and deploying applications ranging from WebSphere Application Server provides the software and tools for build- produce bulletproof InstallShield instal- Java and HTML clients to server-based business components for the ing and deploying Web-based applications. With Standard, Advanced and lations with Java versatility. You can Internet computing platform. JDeveloper 2.0 supports application devel- Enterprise editions, Application Server supports all your e-business target your application for multiple sys- opment based on industry-standard Enterprise JavaBeans (EJB) and needs, from simple Web transaction processing to enterprise-wide Web tems with cross-platform distribution. CORBA component models. Using intuitive and easy-to-use wizards, the applications. An open, extensible solution providing the highest levels of And InstallShield Java Edition 2.5 product provides full support for a rich set of Java standards – servlet, performance, security, availability and scalability, WebSphere Application offers the key features and functionali- JDBC, SQLJ, InfoBus and JFC/Swing. JDeveloper 2.0 comes with a Server leverages your existing IT investment to create new opportunities ty designed to let developers go further servlet engine that allows servlets to be developed and tested within - now and into the future in distribution and deployment. JDeveloper.
WebSphere Application Server Standard Edition v2.02 $ 99 JDeveloper Suite Personal Edition...... $11999 InstallShield Java Edition ...... 474 ...... $66899
ALLAIRE ALIVE.COM INTUITIVE SYSTEMS HomeSite 4.0 Alive e-Show 1.1 Optimizeit 3.0 Professional
HomeSite is the award-winning HTML edit- Alive e-Show is an easy, cost effective desktop application that allows Optimizeit provides a pow- ing tool that lets you build great Web sites non-technical PC users to create and publish streaming media e-shows erful solution for developers in less time, while maintaining Pure HTML. to the Web. Using Alive e-Show, employees can create new content, looking to rapidly track down Unlike WYSIWYG authoring tools, HomeSite integrate existing media, and publish it to the Web with a single click. and fix performance issues in any Java pro- gives you precise layout control, total design It's a great way to integrate slides, digital photography, animation, syn- grams. Optimizeit offers complete profiling flexibility and full access to the latest Web chronize audio and video, add hyperlinks, and supplement with closed capabilities including memory leak debugging, CPU profiling and moni- technologies, such as DHTML, SMIL, Cas- captions. Create e-shows quickly and easily. You create slides in outline toring of object allocations. Easy to use, comprehensive and accurate, cading Style Sheets and JavaScript. Home- mode, record audio and video, and format the e-show using predefined Optimizeit provides real-time thorough information about CPU and mem- Site 4.0 is the only HTML editor featuring a templates with slide styles and placeholders for closed captions too. ory usage, presented in easy-to-read graphs and relevant metrics. Using visual development environment that pre- Allaire HomeSite® is included free, further simplifying any extra cus- Optimizeit, developers get complete, coherent information on any part of serves code integrity. tomization you may need using this HTML editor. their program down to the responsible line of source code. HomeSite 4.0 ...... $8799 Alive e-Show 1.1 ...... $55899 Optimizeit 3.0 Professional ...... $44899
GALILEO DEVELOPMENT SYSTEMS ALLAIRE CLOUDSCAPE INC. Intr@Vision Foundation ColdFusion 4.0 Cloudscape Single User Developer License Intr@Vision Foundation helps bring ColdFusion development to the next With ColdFusion 4.0, create Web applications Building on its technology lead as the industry's first embeddable Java˙ level. It provides an out-of-the-box application security architecture for for self-service HR solutions, online stores, database designed for distributed, off-line, and mobile computing, Cloud- handling your most complex interactive publishing and much more. The scape Release 2.0 is designed to support eBusiness applications such as intranet and extranet needs. integrated development environment that has "smart" eCatalogs and supply chains. Enhancements in 2.0 include: *Multi- Instead of spending 30% of your all the visual tools you need to create Web user concurrency that supports development time adding security applications quickly and easily. From simple hundreds of users. *Advanced to every application you build, it to sophisticated ColdFusion gives you the security that enables only autho- gives you a proven solution with a power to deliver the Web solutions you need- rized applications to read data. single line of code. Intr@Vision faster, and at a lower cost. *Substantially faster load of initial Foundation allows your developers information into the database to focus on building business Cloudscape 2.0 is bundled with Cloudview (a schema browser utility. $ 99 solutions, not infrastructure. ColdFusion 4.0 ...... 354 Includes one year of support from the Cloudscape services organization. $ 99 Intr@Vision Foundation ...... $349999 SkillBuilding with ColdFuion Interactive Training CD. . . . 284 Cloudscape Single User Developer License ...... $89499 WWW.JDJSTORE.COM EJB CASE HISTORY Enterprise Java atSyracuse University Distributed applications written in Java using the EJB model to build reliable and scalable systems
Today’s universities are recognizing the desirability of providing many staff functions for their students through a Web interface. Self-service applications allow students to enroll in courses, manage their personal information and examine their class schedules – and save the university time and expense for staff that would otherwise perform these tasks. In April 1999 New York State’s Syracuse University WRITTEN BY went online to accomplish these activities over the Internet with a self-service application based on FRANK GATES TEnterprise JavaBeans technology. Here’s how it was done.
SIS EJB SIS HTML Web EJB Interface Student Browser Application Interface Server Information Server Calls H Server Manager System T t M le SIS L or App Interface Server
J SIS * SIS Interface Manager: Load balances calls to DB C C Interface the Student Information System Interfaces all Server * SIS Interface: Understands how to communicate s with the Student Information System. Database SIS Server * Student Information System (SIS): The enter- Interface prise student information application Server
FIGURE 1: Online student information environment
The Requirements Syracuse also required an application SIS used at Syracuse. Scalability is Syracuse University had bought a new vendor that would provide first-rate achieved through its multilayer archi- online student information system (SIS) technical support. tecture, where each layer fulfills a specif- from a leading software vendor. Unfor- It became clear that development of ic responsibility. tunately, the system didn’t provide an an application that adapted the SIS to adequate Web interface, and it was built the Web would require a substantial Student Affairs’Application Architecture from the point of view of administrators, effort. A clear separation between the The application architecture devel- not students, complicating how a Web- business logic and presentation layer oped by IBS can be used to develop new based solution could be developed. would be needed to enable customiza- applications and to adapt, as Student The university sought a Web-based tions without affecting the application Affairs does, to third-party applications. student self-service interface for its new logic. EJB promotes this separation. In The outermost layer is the application system and had an extensive list of addition, standard Java-based technolo- user interface. For simplicity, the user requirements for the application. The gies such as Java Servlets and Java Serv- interface is a commonly available interface had to be easy to use and er Pages (JSP) would be needed to write browser (Internet Explorer 3.0 or later responsive over modem connections, the presentation layer. As Java is plat- and Netscape 3.0 or later). The presenta- and it had to work with all popular form independent (particularly on the tion layer consists of servlets running on browsers. The application had to be server) and largely vendor independent, a servlet-enabled Web server. This archi- platform independent and use distrib- an application based on standard Java tecture also supports the use of JSP and uted, scalable technology. It also had to technologies would be the best fit for HTML/Java (JHTML). Applets can also be highly reliable as it would be running this distributed Web application. be used. (Student Affairs uses one small 24/7. Further, the application had to be In September 1998 Syracuse selected applet to facilitate the enrollment implemented using standards-based Student Affairs, a Web application from process.) technology such as EJB. Most important, Interactive Business Solutions (IBS), to Student Affairs’ servlets constitute a the Web interface had to be capable of fulfill their requirements. This applica- very thin presentation layer for the SIS reliably enrolling all of Syracuse Univer- tion provides a scalable Web-based solu- data, which allows the user interface sity’s 15,000 students during its open tion through the use of servers that are designer to focus on designing displays enrollment period. specialized in communicating with the that communicate SIS content to the
44 OCTOBER 1999
Java COM MetaMata www.metamata.com
OCTOBER 1999 45
Java COM E J B C A S E H I S T O R Y students. The resulting presentation links, text and tables. The banner title testing from the Web server could hide layer can be a rich user interface that and logo are also customizable, and a or exacerbate the problem. Back-end guides students seamlessly through the university can readily customize the testing exercises the SIS, the database enrollment process yet is not overly con- footer of each page in the application. server and the IBS SIS Interface Servers. cerned with how the enrollment is Each item can be modified without Back-end testing simulated thou- accomplished. changing any source code. sands of concurrent enrollments per The EJB Application Server is respon- Syracuse University modified the hour. The system was severely overtaxed sible for executing all the business logic appearance of the Web application and performed poorly. Initially, the SIS of an application. In the case of this extensively, supplying the university’s Interface Servers weren’t running in a application, however, the SIS contains logo, using school colors for the menu full production environment. Additional the business logic; the application’s EJB buttons and providing thorough infor- computers were installed, and the tests is a thin layer that makes calls to the SIS mational text for the customized footers were repeated. No further problems via the SIS Interface Manager with para- on each page. The university also pro- were discovered with the SIS Interface meters it receives from the application duced a companion Web site that pro- Servers during these tests. However, servlets. In some cases EJB makes direct vided online instruction on how to use intermittent communication problems read-only SQL calls to the SIS’s database, the new application. between the SIS Interface Server and the either to increase performance or sim- SIS Interface Manager were discovered ply to access data that may not be avail- independently by IBS, and the servers able through the SIS interfaces. The ‘‘ were updated at Syracuse. results are returned to the servlet, which The SIS and the database servers were then formats and displays the results. The cooperative still underperforming during these tests. The EJB Application Server commu- Syracuse spent two months testing and nicates with the SIS through two addi- spirit between fine-tuning these servers to achieve ade- tional layers. EJB communicates directly quate performance. Once sufficient per- with the SIS Interface Manager, which the university formance began to be achieved by the load-balances calls from the EJBs to back end, front-end testing of the Web multiple SIS Interface Servers that per- server and EJB Application Server was form the actual API calls to the SIS. and IBS started. Several problems were discov- With the exception of the user inter- ered and remedied at this time. face layer, which is an Internet browser, accelerated the • The heap size of the Web server and a specific server manages each layer in EJB Application Server needed to be the application. For instance, the pre- expanded. The default maximum heap sentation layer runs on a Web server, testing process size, 16MB, was expanded to 128MB. and the business logic is in EJBs on the • Following one update of the EJB EJB Application Server. These servers and significantly Application Server, the server was can operate on separate computers, and found to be leaking memory, which it there can be multiple servers for each improved had not been doing before. A seem- layer. This obviously increases perfor- ingly minor change in the server mance and reliability. Because the uncovered a memory problem in servers don’t have to run on the same the product. which circular references between kind of computer (thanks to Java), a uni- different EJB components prevented versity can choose the equipment that’s garbage collection of EJBs and many best for each server. resource classes. The server logic was The university’s tests’’ were in two gen- corrected and a new update was Syracuse and Student Affairs eral arenas: functional testing of the quickly made. Student Affairs was installed in Octo- application and performance testing. • Two deadlocks were discovered ber 1998. Syracuse chose to install the During the former they sought to deter- between threads competing for server Web server, EJB Application Server, SIS mine whether the application worked (a or EJB resources. Interface Manager and SIS Interface validation test); during the latter, whether • Unlimited users would saturate the Servers on separate multiprocessor NT it worked in a desirable manner (a usabil- Web and EJB servers. Configurable servers. While the Web server and EJB ity test). Any bugs were reported to IBS. limits were added to control the num- Application Server could be installed on Usability issues were also reported. ber of users accessing the system. AUTHOR BIO any computer that supports Java, the SIS Items judged useful for any university Frank Gates, a software Interface Manager and SIS Interface were performed at no charge; items Summary developer for 20 years, Servers required installation on NT deemed unique to Syracuse were con- The Syracuse University experience currently works for servers due to the SIS API server require- sidered chargeable and were performed successfully demonstrates that distrib- Interactive Business ments. with the university’s approval. All work uted applications written in Java using Solutions.The senior During the six months before Syra- items – bug fixes and usability items – the Enterprise JavaBeans model can consultant on the team cuse did its first online registration, the were then scheduled for repair accord- build reliable and scalable systems. The that developed the IBS university spent its time customizing ing to how critical the defect was. multilayer EJB architecture was essen- Enterprise Application the appearance of the application and Syracuse also spent several months tial in enabling the university to go Server and the Student testing the application components. doing performance testing of the appli- online on time. In addition, the cooper- Affairs application on Because Student Affairs is designed to cation components, which demonstrat- ative spirit between the university and which this article is based, function at any university using the stu- ed that testing in a production-like envi- IBS accelerated the testing process and he is also on the team dent information system, it has a large ronment is essential. The SIS was the significantly improved the product. developing the next set of items that are customizable, first to be tested. The rationale was that version of the EAS. including color preferences for pages, if there was a bottleneck in the back end, [email protected]
46 OCTOBER 1999
Java COM Riverton
OCTOBER 1999 47
Java COM Object www.objcetdes
48 OCTOBER 1999
Java COM Design sign.com/javlin
OCTOBER 1999 49
Java COM A Return to Reflection Adding advanced features to the CodeDocument class à la Borland’s CodeInsight
When we last talked, I promised to finish up the CodeDocu- All we have to ment class I’d so abruptly left behind back in July (JDJ Vol. 4, do, once we have a issue 7). Now, due to millions of desperate letters from fans Class object, is call around the globe, I’ve decided to finish off the series in this the getDeclared- article, tackling reflection once again and ending with a text Methods() function, component that supports syntax highlighting and a simplified which returns an version of something similar to Borland’s Code Insight. Along array containing all the the way we’ll see a few more tricks that JTextArea can do, and declared methods of the in general we’ll just go hog wild in code! class (this includes methods WRITTEN BY declared as private!). Once we have this array we can iterate JIM CRAFTON A Refresher on Reflection through all of the elements in the array calling the Method Those of you who read my last article can just skim through class’s getName() method. If we’re interested in determining this part. For the others I’ll try to explain, quickly, what reflec- the accessibility of a particular method, we can use the get- tion is and why we need it for this article. Modifiers() function: Reflection allows object A, which is interested in object B, to interogate object B for any information object A is interested int mods = aMethod.getModifiers(); in at runtime – without having the source code on the System.out.println( Modifier.toString(mods) + " " + machine. Interested in what attributes the object has? No aMethod.getName() ); problem, just use reflection. Wondering if the object has a par- ticular method? Again, no problem, just use reflection. Now If we’re interested in the parameters a method took, we can that you know the object has a particular method, you want to do the following, using the Method class’s getParameters(), know what parameters the method requires. Just use reflec- which returns an array of Class objects representing the argu- tion! Now you know what the parameters are for the method, ments to the method: but you want to know what your spouse is thinking? Just use...oh, wait, that doesn’t work. Class[] params = aMethod.getParameters(); Well, anyway, reflection is one of the cooler features in the Java language (and oh, how I wish C++ had the same thing!). We can also invoke methods dynamically on an object by Used properly it offers some great benefits. Obviously, for using reflection. First we retrieve the desired method as we did development tools that need to know all sorts of details about above or by using the Class class’s getDeclaredMethod (which the objects being manipulated, this is great. Other uses might is useful if you already know the name and parameters of a be to generate SQL automatically based on some metadata particular kind of method – for example, say you were trying scheme (this was a technique one of the developers used in a to determine if a series of objects has a method called “setText” project I was on recently). When you use tools like Borland’s that takes a single parameter of type String). Then we create an JBuilder, the ability of the Inspector to “know” exactly what array of Object and call the Method class’s invoke() method. properties to display for a given UI component is based com- pletely on reflection. So how do we use it? To start, you need to Class[] argParams = new Class[1]; get the Class object from whatever object you’re interested in. argParams[0] = Object.class; Let’s take a look at the code below. aMethod = aClass.getDeclaredMethod( "addElement", arg- Params ); Vector v = new Vector(); //this is the object we want to //learn more about through Object[] argVals = new Object[1]; //reflection argVals[0] = new String( "A New String Object !" ); Class aClass = v.getClass(); aMethod.invoke( v, argVals );
Any object could have been chosen (Vector, JComponent or The first part of the code gets a single method from the any other valid Java object), and once we have a valid instance aClass variable and then prepares to invoke the method. The we call the getClass() method to get the object’s Class instance. argVals array has its first element set to a new instance of a The Class object serves as the starting point for obtaining all String, and then the invoke method is called: the first parame- sorts of information, such as all the constructors for that ter is the object that the method is being invoked on (in this object or all the declared methods – or even all the fields case our Vector variable from before), and the second parame- (attributes) of the object. Let’s look at what we do once we get ter is the object array of method arguments (methods that take a method from the list of declared methods for the object: no arguments could just pass in null). So we’ve looked very quickly at a simple example of how to Method[] methods = aClass.getDeclaredMethods(); retrieve information about an object, all of it done at runtime, for (int i=0;i 50 OCTOBER 1999 Java COM Java COM ation of the new outer class. STATE_VARIABLE_TYPE_INPUT and STATE_VARIABLE_INPUT are used to determine when a variable or variable type is entered. As the user types, the state will also be changed, which is handled by the checkForState- Change() method inside the processChar() method. Inside checkForStateChange() the method looks at what kind of character has been passed in and then makes a call to check- State(), which either ouputs diagnostic information or adds the appropriate data to model being built up. Then check- ForStateChange() calls the changeState() method, which actu- ally changes the CodeDocument’s state. Depending on the character passed in, checkForStateChange() may also call other methods to handle things like a “.” or a “(”, both of which can cause reflection to take place. Figure 1 shows this in dia- grammatic form. The handleDot() and handleOpenParen() methods will be discussed in more detail in the next section, as these are responsible for triggering events. Events FIGURE 1 The CodeDocument now both triggers and listens to events in this new version. Every time the handleOpenParen() When a State Isn’t a State (and Other Dumb Plays on Words...) method is called, the MethodEvent is fired, via the fireMeth- For the CodeDocument to do its work it has to know its cur- odEvent method. This allows outside controls to be notified rent state – in other words, not only what word you’ve just whenever the CodeDocument is ready to display the argu- typed in (or inserted), but whether or not you’re just typing in ments of a method, similar to what happens in JBuilder when the package name, typing in imports, creating a class declara- you type in a method and then type the “(” character and the tion or creating variables in code within a method. The docu- tool tip pops up with all the method’s arguments. Outside con- ment also has to know what type the variable is as well as trols interested in this event can use the CodeDocument’s whether you’ve worked with it before so it can look it up if nec- addMethodListener() method to register themselves as listen- essary. Obviously, this could get quite complex, and to make ers to the documents event, assuming they implement the this function as a production tool you’d end up with a sophis- MethodListener interface given in Listing 1. ticated state machine and parser to work all this out. In the The document also listens to events, which is how the interest of time (yours) and energy (mine), I’m going to devel- drop-down list with the available methods for a given object op a simplified version of this that should serve as a possible works. If the handleDot() method is called, the CodeDocu- model or at least inspire you to feats greater than mine. ment gets the current position and extracts the appropriate So, back to State. To keep track of the state of what you’re text (see the earlier JDJ articles pertaining to the CodeDocu- typing in, I’ll introduce several new constants as well as a ment for exactly how this is done) until the class name is number of new variables to keep track of it all. found for the variable in question. This is currently the To save the information for future use, we’ll create several Achilles heel of the whole thing, and those of you interested in small classes to hold the information for us, namely, class making this more sophisticated will want to start improving CodePackage to hold information about the package just cre- this part, but it works for our purposes. Once the class name ated; class CodeClass for the outer public class that’s normally is found, a new set of attributes is created and the classLister created; and class ClassElement, which will hold all the attribute’s setClassName() method is called, which sets the dynamically discovered fields and methods we display in our classLister’s class name attribute. To retrieve all the info, the drop-down listbox. To simplify all the reflection code we’ll use method then calls the classLister’s listAll() method, which a class called ClassLister, which will do all the reflection work returns a Vector containing a list of ClassElement objects whenever we encounter a possible need to get at the informa- (which are simply convenient ways to store all the method or tion. attribute data). The following code shows the possible states we’ll keep Now that all the data is put together, we can go ahead and track of in the CodeDocument: create our drop-down list. But wait, you say. Where on earth are you going to put it? And how? Patience, my young one, all private static final int STATE_TEXT_INPUT = 10; in good time! private static final int STATE_CLASS_INPUT = 11; One of the neat features of the Document model class is the private static final int STATE_VARIABLE_INPUT = 12; ability to insert not only text of different formats, but also visu- private static final int STATE_PACKAGE_INPUT = 13; al components, like drop-down listboxes. To do this we use the private static final int STATE_IMPORT_INPUT = 14; SimpleAttributeSet class and create a new instance. Then, private static final int STATE_VARIABLE_TYPE_INPUT = 15; using the StyleConstants class’s static method setCompo- nent(), we pass in our newly created list box and the attribute The generic default state (STATE_TEXT_INPUT) represents set we just created. Let’s look at the code in Listing 2. typing in text, as I’m doing right now. STATE_PACK- The setComponent() method attaches the newly created AGE_INPUT defines when the CodeDocument determines JComboBox to inputAttributes object. To make this show in that the user is typing in a package name. This is needed for the document, we use the insertString() method at the current the reflection to pick classes just created in the package. position plus one, with a space (“ ”), and passing in the STATE_IMPORT_INPUT is used to describe when the user is attribute set. Notice that we’re calling the super classes insert- typing in the name of an imported package, like “java.lang.re- String() method. Otherwise we’d end up cycling through all flect.*”, for instance. STATE_CLASS_INPUT signifies the cre- our code, which we don’t need to do at this point. 52 OCTOBER 1999 Java COM Force 5 www.force5.com OCTOBER 1999 53 Java COM The other thing that’s important is to register the CodeDoc- • isNameAClass(), which returns true if the supplied String is ument as a listener to the JcomboBox. This is done so the a class (like listAll(), the String passed in to isNameAClass() CodeDocument knows when the user has selected an item does not have to be a fully qualified class name), or false if from the list and can safely remove the JComboBox and insert the String is not a class name. the selected text back into the document. Which is why, as • addPackage, which adds a package name to its internal list you’ll see in Listing 3, the declaration for the CodeDocument (a Vector) of known packages class has also changed, and yet another method has been added. Tying It All Together The ClassElement stores the information about any of the Let’s make a simple test application to try this out. Listing 4 methods or attributes in the list. The Element value, which shows how it works. Although it looks a bit long, it’s actually stores the actual name of the attribute or method, is retrieved. pretty simple. The main() creates new instances for a frame After this, the combo box is removed and the string retrieved (class TestFrame – we’ll get to that in just a bit), an editor (the from the ClassElement is put in its place. infamous JTextArea component) and the doc (our beloved CodeDocument). A keywords list, of type Vector, is created and The ClassLister all the Java keywords are added to it (this is what takes up the The ClassLister class is at the heart of all the reflection that bulk of code). The CodeDocument setKeywords() method is goes on in the CodeDocument. Its primary method is the called to set the CodeDocument’s keyword list. The frame is listAll() method, which uses the ClassLister currentClass- then registered as a listener to the CodeDocument by the Name attribute to attempt to return a Vector containing a addMethodListener() method. The editor’s Document model complete listing of all methods and attributes belonging to is set with a call to setDocument(), which sets the CodeDocu- the class named from the currentClassName attribute. The ment as the editor’s Document model. The frame size is then first thing the listAll() method tries to do is obtain a Class set and…we’re done! object from the currentClassName String. This is done via the If you run this, remember to type a few nonkeyword char- Class class’s static method classForName(), which takes a fully acters (like “//” followed by the actual text). Otherwise you’ll qualified class name and attempts to return a valid Class encounter a known bug, which can be looked up on the instance. A fully qualified classname would be something like Swing Web site (for more information look at http://develop- “java.util.Hashtable” or “com.sun.java.swing.JListBox”. Since er.java.sun.com/developer/bugParade/bugs/4128967.html). the String parameter to the listAll method may not be a fully qualified name, the ClassLister keeps track of a list of pack- Conclusion ages it knows about. Thus, if the first try of the class match We’ve now covered how to make our CodeDocument, fails, the listAll() method catches the exception and tries highlight use, defined syntax, control, numbers, strings and prepending the package names it knows about to the current- comments. Along the way we’ve added code completion (à ClassName until a Class instance is successfully created or it la JBuilder’s Code Insight) and method hints using the runs out of package names, in which case the method fails. If magic of Java’s reflection classes. We’ve learned how to use the method does create a Class instance, it uses reflection, as the power of reflection to build the start of a really useful discussed above, to add all the method and attribute names tool as well. I hope you found this as interesting a topic as I to a Vector, packaging each method or attribute into a Class- did ! Element object that is added to the Vector list and then returned. AUTHOR BIO ClassLister has several other methods: Jim Crafton is part of the research and development team at Improv Technologies • listMethods(), which does something similar to listAll(), (www.improv-tech.com), helping to develop a new production-quality animation tool. He also except it only returns methods develops advanced graphics software that can be seen at www.one.net/~ddiego/. • listMethodArgs(), which, given a method name, tries to list out the arguments for the method [email protected] Listing 1 super.insertString(currentPos + 1, " ", inputAttributes); } public class MyLabel extends JLabel implements MethodListen- catch (Exception ex){ er{ ex.printStackTrace(); ...//code } public void methodAction(ActionEvent e){ this.setText( e.getActionCommand() ); Listing 3 } public class CodeDocument extends DefaultStyledDocument } implements ActionListener{ ...//more code ..//more code MyLabel aLabel = new MyLabel(); public void actionPerformed(ActionEvent e) { JTextArea editor = new JTextArea( new CodeDocument() ); try{ CodeDocument doc = (CodeDocument)control.getDocument(); JComboBox comp = (JComboBox)e.getSource(); doc.addMethodListener(aLabel); ClassElement elem = (ClassElement) comp.getSelect- Listing 2 edItem(); String item = elem.getElementValue(); SimpleAttributeSet inputAttributes = new SimpleAttribute- this.remove(listOffs, 1); Set(); super.insertString(listOffs, item, null); ..//more code... currentMethod = item; try{ } JComboBox c = new JComboBox(); catch (Exception ex){ c.addActionListener(this); ex.printStackTrace(); } StyleConstants.setComponent(inputAttributes, c); } 54 OCTOBER 1999 Java COM American Cybernetics www.multiedit.com OCTOBER 1999 55 Java COM Listing 4 keywords.addElement("else"); keywords.addElement("throws"); keywords.addElement("false"); keywords.addElement("transient"); package CodeEditor; keywords.addElement("final"); keywords.addElement("true"); keywords.addElement("finally"); keywords.addElement("try"); import com.sun.java.swing.*; keywords.addElement("float"); keywords.addElement("var"); import java.util.*; keywords.addElement("for"); keywords.addElement("void"); import java.awt.event.*; keywords.addElement("future"); keywords.addElement("volatile"); import java.awt.*; keywords.addElement("generic"); keywords.addElement("while"); keywords.addElement("if"); public class Application1 { keywords.addElement("implements"); doc.setKeywords(keywords); keywords.addElement("import"); doc.addMethodListener(frame); keywords.addElement("inner"); public static void main(String[] args) { keywords.addElement("instanceof"); editor.setDocument(doc); TestFrame frame = new TestFrame(); keywords.addElement("int"); TextPane editor = new JTextPane(); keywords.addElement("interface"); frame.setSize(400,400); CodeDocument doc = new CodeDocument(); keywords.addElement("long"); frame.getContentPane().add(editor); keywords.addElement("native"); frame.show(); Vector keywords = new Vector(); keywords.addElement("new"); } keywords.addElement("null"); } keywords.addElement("abstract"); keywords.addElement("operator"); keywords.addElement("boolean"); keywords.addElement("outer"); class TestFrame extends JFrame imple- keywords.addElement("break"); keywords.addElement("package"); ments MethodListener{ keywords.addElement("byte"); keywords.addElement("private"); public void methodAction(ActionEvent keywords.addElement("byvalue"); keywords.addElement("protected"); e){ keywords.addElement("case"); keywords.addElement("public"); this.setTitle( e.getActionCommand() keywords.addElement("cast"); keywords.addElement("rest"); ); keywords.addElement("catch"); keywords.addElement("return"); } keywords.addElement("char"); keywords.addElement("short"); } keywords.addElement("class"); keywords.addElement("static"); keywords.addElement("const"); keywords.addElement("super"); keywords.addElement("continue"); keywords.addElement("switch"); keywords.addElement("default"); keywords.addElement("synchronized"); keywords.addElement("do"); keywords.addElement("this"); keywords.addElement("double"); keywords.addElement("throw"); keywords.addElement("extends"); SlangSoft www.slangsoft.com 56 OCTOBER 1999 Java COM Insignia www.insignia.com OCTOBER 1999 57 Java COM EJB HOME The Business Advantageof EJB PART 1 Developing portable EJB applications hat’s all this hype about portability? Portability has been a hot topic since Java’s arrival just a few years ago, so I’m going to devote some space toward understanding portability issues centered around the Enterprise JavaBeans architecture and development.This month I’ll discuss the various types of portability and Java’s relationship to each; then I’ll touch on the portability goals of the EJB specification and where EJB portability lacks maturity (and why not to worry). Next month I’ll pro- WRITTEN BY vide tips on EJB portability as well as code examples depicting how you can help achieve the JASONWESTRA Wpromise of EJB portability through solid design and coding practices. Competitive Advantage of Portability Types of Portability Platform Portability Portability is a true concern in the As previously mentioned, there are There’s a real need to have operating minds of many IT executives who see different types of portability. Applica- system portability. The World Wide Web the need to develop applications with tions that are portable across these areas had a profound impact on the need for faster times-to-market and across more can be quickly modified to meet cross-platform (OS) software because platforms than ever before. The porta- changes in your business or technology you couldn’t tell what platform an Inter- bility hype is fostered by the need to and will be more easily maintainable net user was surfing on. Java combated bring new products to market at ever- than nonportable, “stovepipe” applica- this problem by providing OS portability increasing rates – products that are as tions. For instance, rather than making via the Java Virtual Machine, which easily compatible with legacy systems as upgrades to multiple versions of an translates operations into the correct OS with Web-enabled systems. This mission application for each specific platform, platform’s API. This common concept is is heavily reliant on the interoperability one upgrade is made to one application. called wrappering. of software across a number of areas, Depending on the focus of your soft- Before I started a career in software including platform/operating systems, ware, you may worry about one or two development, I thought a wrapper was resources such as databases and trans- types of portability while shifting the simply packaging for my chewing gum; action management services, and multi- burden of the others to a middleware however, wrappers have revolutionized ple development languages/component provider. Let’s take a look at each type of more than the candy industry. They’re a models – most recently, Enterprise Java- portability and understand which ones prime enabler for the interoperability of Beans components. will directly impact a Java/EJB developer. heterogeneous components in the soft- ware industry. Interoperability through a wrapper or “adapter” design pattern is achieved by providing an acceptable interface that a client component expects and can communicate with effectively (see Design Patterns: Ele- ments of Reusable Object-Oriented Soft- ware by Gamma et al.). Thus an existing EJBHome EJBHome component with an incompatible inter- EJB EJB face may be called by other software via Component Component a wrapper, achieving the reuse we’ve Client come to expect in component-based development. An example we should all EJBObject EJBObject be familiar with: a JVM wraps multiple operating systems in an acceptable EJB server's common interface, obviating the need default Third Party's for developers to build multiple OS-spe- EJB Container EJB Container cific versions of their software for each platform. Transaction Management Security The key point introduced here, and EJB Server Resource Pooling one I’ll refer to often: the wrapper design Life Cycle Management pattern is important to software porta- bility (not just a convenient place to put FIGURE 1: EJB component execution environment old chewing gum). 58 OCTOBER 1999 Java COM SL Corp www.sl.com OCTOBER 1999 59 Java COM Resource Portability grammer to code a piece of functionality for your application that can A flexible application is built with an awareness of resource portability. be wrapped to look like a CORBA component. As you can see, portabil- Examples of resources might include transaction management services, ity allows quicker time-to-market for your products through the reuse naming services, communication protocols or a database management of existing assets, even human assets. system. For instance, a commercial product built to access a storage Java provides platform portability, but you’re tied to one language, resource such as a database should remain as neutral as possible with Java. While CORBA and COM alleviate this single-language portability regard to its persistence mechanisms. Designing flexibility into this prod- issue, they’re still quite different from one another. CORBA objects may uct might include providing a layer of insulation between your business be deployed on any platform, while COM components are currently objects and how they’re stored. This will allow your customers to decide tied to the Windows operating system. Thus CORBA and COM have which database they wish to use with minimal impact to your product. potentially different markets. While CORBA fits well in heterogeneous With so many types of storage mechanisms, including RDMSs, object- environments, COM is ideal for pure Microsoft shops. The EJB specifi- relational databases, embedded databases and pure ODBMSs, you have to cation seriously addresses component model interoperability with take database portability seriously. CORBA; however, it leaves COM integration up to the EJB server ven- Java provides some degree of insulation against platform-specific dor’s imagination. database code through its JDBC API. However, JDBC is flexible and pow- erful enough to allow vendor-specific code to be written through its Enterprise JavaBeans Portability database metadata features. You still have to use sound design patterns One of the primary goals of Enterprise JavaBeans is to provide a com- and wrappering techniques to ensure minimal impact when changing ponent model for building portable server-side components that storage schemas. As we’ll see, EJB specification 1.0 provides further guid- addresses Java’s lack of language portability and more. For the remainder ance on resource portability. of this article I’ll focus on how the EJB specification lays the groundwork for Java’s portable, server-side component model. Language/Component Model Portability Language portability is the ability to support multiple development Portability Goals in the EJB Specification languages. This form of portability is provided to the development “Enterprise JavaBeans will make it easy to write applications: applica- community through two widely regarded standards: Common Object tion developers will not have to understand low-level transaction and Request Broker Architecture and Component Object Model. CORBA state management details; multi-threading; resource pooling; and other and COM allow components coded in multiple languages to commu- complex low-level APIs….” —EJB specification 1.0, section 2.1: Overall nicate with each other through an interface definition language. IDL Goals provides mappings between disparate languages such as C, C++, Java, Though not stated explicitly, the net result of this goal is the promise of Visual Basic (VB) and even COBOL. These unique languages are interoperability between third-party EJB vendor products. This goal implic- wrapped (once again, that valuable wrapper pattern) in recognizable, itly introduces the notion of a component execution environment, the cen- acceptable interfaces that foster reuse not only of business logic but tral ingredient in providing EJB portability. In my first “EJB Home” column I also of human resources by way of current IT staff. For instance, lan- described this concept briefly, but I’ll review it again as a refresher. guage portability means you can use an existing COBOL or VB pro- A component execution environment typically consists of an EJB server and one or more EJB containers (see Figure 1). While JavaBean client components typically run within a visual container, EJBs execute within server-side containers. The container shelters your EJB compo- nent from its runtime platform by managing all of its interactions with the operating system. Together, an EJB server and its containers provide your components with access to distributed runtime services such as state management, distributed transaction management, multithread- ing and resource pooling, as stated above. The Enterprise JavaBeans specification provides guidelines to encourage EJB server and container providers to build their products in a portable manner (see section 17 of specification). Figure 1 shows how an EJB server is making use of a third-party EJB container. Because the Career third-party container was built according to the EJB specification, it’s portable to any EJB server and runs seamlessly within this component execution environment. EJB’s component execution model is a prime example of how portability cuts time-to-market for products. An EJB server provider lacking skills in certain areas, such as object databases, could license a third-party EJB container that maps entity beans to an Central object database and viola! – it’s in the EJB server business! “Enterprise JavaBeans applications will follow the ‘write-once, run any- where’ philosophy of the Java programming language. An enterprise bean can be developed once, and then deployed on multiple platforms without recompilation or source code modification.” —EJB specification 1.0, sec- tion 2.1: Overall Goals This EJB portability goal is easy! It simply reiterates Java’s approach www.careercentral.com/java to providing OS portability from the standpoint of EJB. The very nature of EJB means it should run on any Java-compatible platform via the JVM. The benefit of “write-once, run anywhere” on the server is the ability to easily scale your application from a lowly workstation to a high-end enterprise server as volume demands. Compare that to the time it would take to rewrite a nonportable application from one serv- er platform to another! By the time you finished, your dissatisfied cus- 60 OCTOBER 1999 Java COM IAM www.iamx.com OCTOBER 1999 61 Java COM E J B H O M E EJB Portability:Myth or Reality? While the EJB specification 1.0/1 has laid the foundation for building portable enterprise beans, there is much left to be specified before true interoperability will EJBHome be a reality. The EJB specification is vague in a number of areas important to EJB Enterprise COM portability, including a container Component Client Bean provider’s responsibilities, multiple-ven- dor EJB server integration, CORBA and EJB EJBObject security models, distributed/asynchro- EJB Container nous event notification and mappings for COM integration. Without addressing these areas in future drafts of the EJB spec- ification, EJB portability will be compro- EJB Server mised. Am I worried? No. Fortunately, Java- Soft and a contingent of EJB proponents are working on these issues as I write. FIGURE 2: COM component wrapped as an EJB Summary tomers would have given their business understanding the importance of porta- Portability offers tremendous business to a company that could meet their bility, defined the Enterprise JavaBeans advantages by enabling quicker time-to- business needs sooner. component model to allow for the inter- market for new products that don’t need to operability with other component models be rewritten for each platform in question. “The Enterprise JavaBeans architecture such as COM/DCOM (Distributed COM) Portability also reduces maintenance costs will define the contracts that enable tools and CORBA. A separate specification of your applications and promotes reuse from multiple vendors to develop and describes the mapping of EJB to CORBA. It across disparate technologies, allowing you deploy components that can interoperate is available for download at www.java- to use existing hardware, business logic and at runtime.” —EJB specification 1.0, sec- soft.com/products/ejb/docs.html. even software development talent. tion 2.1: Overall Goals Enterprise JavaBeans will soon be EJB specification 1.0 defines two types trusted to help build portable, server- of contracts: between enterprise beans side components and applications, pro- and their client and between enterprise ‘‘ viding the business advantage IT man- beans and their containers. The enter- In Part 2 I’ll cover agers seek. The EJB specification prise bean-client contract ensures that addresses key issues around the integra- the enterprise bean provider (e.g., enter- tion of disparate component models prise bean developer) and container tricks, traps and and portability between multiple EJB provider must collaborate to offer vendors, providing early EJB adopters unique object identity, method invoca- with a competitive advantage in the tion capabilities and an EJB home (e.g., techniques in marketplace. Furthermore, EJB vendors factory interface and class). In a perfect are offering increasingly powerful tools world upholding this contract provides to build EJB applications. client-side portability with respect to designing and However, even though the recently various EJB server vendors. released EJB specification 1.1 addressed A second component contract is issues around entity bean compatibility defined between the enterprise bean and coding portable (i.e., entity beans are now mandatory), its container. By upholding this contract, there is still much to be fulfilled concern- an enterprise bean will be deployable ing EJB’s portability promise. It is lacking within multiple vendors’ tools, and will in critical areas, including security, sys- be able to use the runtime services of any Enterprise tem management and EJB server com- vendor’s EJB server. This lists a number of patibility. While the specification defines services, such as lifecycle management, the need for compatibility on numerous that the container must offer an enter- JavaBeans fronts, it doesn’t qualify the means to this prise bean, as well as the interfaces that end. As vendors pump out new EJB prod- allow the container to manage the bean ucts, how can you be sure of the portabil- in a component execution environment. ity promised by the specification? The implementation’’ of component In Part 2 I’ll cover tricks, traps and “The Enterprise JavaBeans architecture model portability in EJB is vendor specific. techniques in designing and coding will provide interoperability between An example implementation might have a portable Enterprise JavaBeans. Expand- enterprise Beans and non-Java program- COM or CORBA component “wrapped” in ing on what you’ve learned in this arti- AUTHOR BIO ming language applications. The Enter- an EJB container, providing a client with cle, the code examples in Part 2 will give Jason Westra is a prise JavaBeans architecture will be com- EJB interfaces just like a normal enterprise you an understanding of how to apply managing partner with patible with CORBA.” —EJB specifica- bean (see Figure 2). You can see the busi- the wrapper design pattern to your Verge Technologies Group, tion 1.0, section 2.1: Overall Goals ness advantage of EJB’s component model development repetoire to ensure EJB Inc., a Java consulting firm Portability across multiple languages is portability – existing and new business portability. Until next time.... specializing in Enterprise important in developing software applica- logic written in other component models JavaBeans solutions. tions. The creators of the EJB specification, will be reusable from your EJB application. [email protected] 62 OCTOBER 1999 Java COM 9Net www.9netave.net OCTOBER 1999 63 Java COM SYS-CON RADIO SYS-CON RADIO INTERVIEWS WITH... GRANTWOOD&DANIEL BERG, AND MARTINHARDEE Broadcast live from San Francisco at JavaOne going after Java developers and letting Wood: You know how the Web is right them know that here is a new channel for now; every site is different. How do you them to deploy their application. And it’s find your way through a site? You have to really a “no brainer.” Grant could write an claw through it. Since we’re not doing application and run it on a platform allow- content anymore only applications, we’re ing a user to access that software from doingA: things much more familiar to users. anywhere, and he doesn’t have to change When someone turns on their cable box anything in his application. There are no and it logs into a Speiros server some- APIs. It’s all transparent through the VM. It where, it gives them a little menu with offers developers new opportunities and icons for their applications. You didn’t channels. have to browse anywhere. You could Wood: A developer could download search and say I want to see word proces- GRANT WOOD & DANIEL BERG Speiros and log into a server somewhere sors, and it might bring up 50 word OF CYRUS INTERSOFT that would not only give him access to an processors; you can click on them, get open source project that he may be work- information and bring up the Web page of JDJ: Joining me from Cyrus Intersoft cation. What we do is provide a transpar- ing on or a project for work, but the tools the guy who developed it. But all you do is Grant Wood, an engineer, and ent platform on which to deploy the appli- heA: uses to develop that could be handed to launch it is double-click on it. And that Daniel Berg, the chief technology cations. For example, if you were to take a to him from the server as well. And those could be coming from anywhere on the officer. What is your involvement in regular Java-based program, say a word tools could be updated and changed on a Web. the Java industry? processor, most likely you developed daily basis. All you need to know is point and click Berg: We’re a software start-up based in access to a file system (in order to read or What we have is a vehicle for doing – it’s that simple. Now you know how to Q:Minneapolis, Minnesota; we have an Inter- write a file); since it’s probably an applica- real time deployment of software as well. use that kiosk in the mall, that set-top net application platform that allows any tion, what we can do is run that applica- As a developer, I could log into a server. I box, or your MAC, it really doesn’t matter. Java-based software application and applet tion. You click on an icon and it comes would have my files and any shared files I We’re really delivering on the promise of to be distributed anywhere. It’s anytime, into our environment; it’s a run-time envi- was working on. They could put it all on a Java, “write once, run anywhere.” You anywhere computing, utilizing the Internet ronment without installation. It almost server, and now when people login, could do that before, but now you can in newA: ways. behaves like an applet – you can go to a maybe that’s how they check out their actually get to it anywhere. You could sit We’re delivering the capability to make site or to our URL, and the application software. They just click on the program, down anyplace because now your appli- your digital presence (e.g., your prefer- starts execution. write it, compile it and they’re done. You cation is a full-blown application. It’s out ences, file systems, the applications you Now when I go in there and do a file don’t have to learn the way they check it on the Net. Your files are something we like to access most) meet up with your dialogue or file open, I not only see local out. They could be using CVS, JC...whatev- deliver as well. As you login, here’s your physical presence at any given point, any file systems but also any remote file sys- er they want. It’s really an excellent plat- home directory and maybe you’re con- place on the Net. I could be at the airport tems I’d have access to. We can dynamically form for distributing, computing and nected to 150 different servers out there, using a kiosk, a PDA or whatever, and offer some of these services to applications. development. It takes a lot of the thought and because your files and your applica- after making sure that whenever I go in We can take applications that have been out of the back end of it and allows you tions are on the Internet, it doesn’t matter and establish authentication, all my appli- developed with multi-tiered environments to hand out tools or the tools of choice to where you are. You don’t have to install it cations are available there, including all that have app servers and all the different whoever is using the links. on your box or keep your files with you my file systems, security services and all pieces of the equation, and they will still when you leave your home machine. the stuff that go along with providing OS- work on top of our platform as long as JDJ: Two things I’ve always heard Why would you even keep anything in a type services on the Internet. whatever you are deploying is Java. from Java developers that are the local box when you can just keep them all most important are the ease of use out on the Internet? JDJ: It seems like it’s a very broad JDJ: Who are some of the people and speed. Berg: We have a developer’s release Q:category of application servers. Q:who are using your technology and Q:Wood: Well, can you click an icon? available on our Web site, Would you fall under that category? in what ways are they using it? CyrusIntersoft.com, and we’re looking for Berg: I would say no because we don’t Berg: We’re initially going after ISPs and JDJ: That’s all I really need to know. developers to come download it and try it offer the same things an application server service providers and giving them new Give us a little idea of that. Tell us out. wouldA: offer as far as services to the appli- waysA: of deploying services. We’re also howA: it works. 64 OCTOBER 1999 Java COM Worldwide Internet www.wipc.net OCTOBER 1999 65 Java COM there’s going to be even more. We where you have to be part of the commu- restructured things so you could find what nity and have to be known. But primarily you needed, from discussion topics to we’ve made access to the JDC easier to industry solutions and products. Based on find and easier to access once you get the responses we’ve gotten so far, I think there. we hit the nail on the head. We’ll continue to evolve it of course. JDJ: What can we expect in the future from the Web site? JDJ: Tell us about some of the feed- Hardee: We did community source this back you’ve gotten and if it influ- Q:year and have really ramped up the Java enced your redesign? community process, which we’re trying to Hardee: We’ve actually done a lot of make more of a Web-based activity. One Q:these improvements incrementally. About thing I’m interested in, our site’s been MARTIN HARDEE six months ago we did a survey on the around for a while and while we use a lot OF JAVASUN site; users said the technology has grown of Java technology, including Java Web We redesigned the site slightly. tremendously so they couldn’t find any- Server,A: parts of the site are still running JDJ: Joining me right now is Martin Hardee: Hardee, manager of the We thought about all sorts of radical thing anymore. The first thing we did was Apache. We’re really interested in using java.sun.com Web site. Since we’re redesigns as you always want to do. We reorganize the products in the API’s page. Java Server Pages. We’re doing a lot of at JavaOne, tell us a little bit about do surveys continuously and look at all It wasA: organized both by APIs and alpha- servlet work right now. Our commerce the JavaOne Web site. What do you the Web feedback. We probably get thou- betically. We also built an A-to-Z index of system and the JDC are all servlet based, think is its coolest part? sands of comments a year. We did some the important items on the site, which has so under the hood where you don’t really Q:Hardee: The JavaOne Web site is actually remoteA: usability tests on the phone where been very popular. In the first week, it was see anything, we’re definitely having a lot a subsite of java.sun.com – we’d call people in Australia or some one of our top 20 URLs on the site. We of fun playing with servlets and JSPs. If java.sun.com/JavaOne. I think probably other country and ask them to look at get about a million to two million page you have any comments, go to the feed- the coolest thing our site does is we aspire some mock-ups we had. We learned peo- views a day. back links, and all your comments go into to getA: the community together. You see it ple really like the look of the current site. The hits range is up to 6–7 million a database. We read them, route them on the Java developer connection, and I We pretty much stuck with something that hits a day. We’ve also tried to marry and everything else. think we’ve seen it at JavaOne where we looks the same, but the technology has java.sun.com and the Java developer con- have voting and things for the applica- grown so much. nection subsite together for a more grace- Q:JDJ: You actually read them? tions, but it is really the attendees that are Last year we did almost 250 different ful transition. And the JDC – a few months Hardee: Somebody has the job of read- building things and putting them together. discrete full technology releases on the ago you had to login for everything. ing them and figuring out where they go, site, which is basically one every working We’ve taken a lot of that off so there’s which is a tough job. We track all the JDJ: Let’s get to the Java Sun site. It day. There’s an explosion of technology more free and easy access. We’ve left on comments in the database and make sure Q:looks a little different. and with the Java community process login for the discussions and other things theyA: get answered. Founded in 1996, Visualize, Inc. is the premier data visualization provider with over 20 years total of Java Development expertise. Our products offer: • 2D & 3D Graphics Geek • User Interaction • Analytical Capabilities • Rapid Deployment VantagePoint: A class library for embedding graphical functionality in a Java application DataVista Pro: Cruises An applet designed to graphically display data within a web page For a free evaluation copy of our software visit our web site www.visualizeinc.com or contact [email protected] www.geekcruises.com 1819 E. Morten, Suite 210 Phoenix, AZ 85020 602-861-0999 66 OCTOBER 1999 Java COM KL Group www.klgroup.com/pagelayout OCTOBER 1999 67 Java COM CORBA CORNER What’s Coming inCORBA 3? Three major categories of specifications enhance CORBA integration with Java and the Internet he next release of the CORBA specification will be a major one, CORBA 3.0. The last time the major release number was incremented – to CORBA 2.0 – it signified the stan- dardization of interoperability. What’s new and different WRITTEN BY enough in this version for OMG to increment the major JON SIEGEL Trelease number this time? Despite its compact designation, Introduction to CORBA 3 the IDL for your object into a file that CORBA 3 isn’t a single specification – The specifications included in the you can then compile in any program- instead, it’s the collection of specifica- designation CORBA 3 divide neatly into ming language, on any ORB, allowing tions, adopted individually, that will be three major categories that we’ll cover in you (or your friends) to write CORBA added to the current CORBA 2.3 to form the following order: clients in any language, on any IIOP- the CORBA 3.0 release. Although we use • Java and Internet integration speaking ORB, that can invoke your Java “CORBA 3” as shorthand to refer only to • Quality of service control object. the new parts, the official designation • CORBA component architecture This does a number of things. It CORBA 3.0 refers, formally, to the entire turns Java object programmers into CORBA specification book. With the post- Java and Internet Integration CORBA object programmers, and lets ing of final submissions for the CORBA The three specifications discussed Java objects play in CORBA’s multilan- Component Model (CCM), Scripting and below enhance CORBA integration with guage environment. (Unfortunately, it the Persistent State Service (PSS) on the Java and the Internet. doesn’t do anything for Java client pro- OMG Web site in early August, all parts of grammers!) According to the first draft CORBA 3 are finally available. Votes on Java-to-IDL Mapping of EJB 1.1, it’s a future requirement for these last few parts will be underway CORBA 3 adds a Java-to-IDL mapping Enterprise JavaBeans interoperability when you read this, and are expected to to the “normal” IDL-to-Java mapping and will ensure that EJBs can play in be completed by the end of 1999; check you’re familiar with if you’ve done any this multilanguage environment as OMG’s Web site for the latest word. Java/CORBA programming. To use it, well. There are about 10 new specifications you start out by writing RMI objects in It’s not a round-trip mapping, quite in CORBA 3, and I’ll touch on all of them what the specification refers to as the intentionally. Since out and inout para- here. Java programmers will be particu- “RMI/IDL subset of Java.” It’s a pretty meters don’t occur in Java, the reverse larly interested in the reverse Java-to- full subset; restrictions affect things mapping has no element that corre- IDL mapping and the CCM’s embracing such as multipath inheritance of over- sponds to the Holder classes in the IDL- of Enterprise JavaBeans (EJBs), so I’ll put loaded methods, name case collisions, to-Java mapping, and some IDL types some extra detail into these sections. and private types in interfaces. (Java will never occur in the IDL output from I’ll give you the URL for every specifi- allows private types in distributed inter- rmic. In some ways, though, the map- cation we discuss here. Documents faces. CORBA can’t seem to figure out ping is pretty clever: variables that under consideration for all of OMG’s why anyone would want to keep a dis- appear only in Java set-and-get opera- works in progress are available to mem- tributed variable private.) Objects must tions will be mapped to an IDL bers and nonmembers alike at extend java.rmi.Remote, and exceptions Attribute. www.omg.org/schedule. Find the pro- must inherit from java.lang.Exception. This specification is available from cess or future specification you’re inter- Obviously, CORBA objects passable by the Web at www.omg.org/corba/clch- ested in and click on it. This will bring value play a large role in the CORBA- pter.html#jilm. up a new page with URLs for all related side implementation of this specifica- documents. For specifications, go to tion. Firewall Specification www.omg.org and look down the left- Once you’ve written the objects, two The CORBA 3 firewall specification hand side of the page for “The OMA”; all things happen: first, by compiling defines transport-level firewalls, appli- specifications are available under that through rmic with the proper options cation-level firewalls and (perhaps most heading. You can download any of these set, your objects generate CORBA stubs interesting) a bidirectional GIOP con- OMG documents, specifications, or and use IIOP instead of RMI protocol. nection useful for callbacks and event works in progress without charge. Second, the RMI compiler will output notifications. 68 OCTOBER 1999 Java COM Palm Computing www.palm.com OCTOBER 1999 69 Java COM C O R B A C O R N E R Transport-level firewalls work at the defines a number of asynchronous and CORBA Components Package TCP level. By defining (courtesy of time-independent invocation modes CORBA Objects Passable by Value IANA) well-known ports 683 for IIOP for CORBA, and allows both static and Termed valuetypes, objects passable and 684 for IIOP over SSL, the specifica- dynamic invocations to use every by value add a new dimension to the tion allows administrators to configure mode. Results of asynchronous invoca- CORBA architecture that previously firewalls to cope with CORBA traffic over tions may be retrieved by polling or call- supported passing (and invocation) the IIOP protocol. There is also a specifi- back – the choice is made by the form only by reference. Like conventional cation for CORBA over SOCKS. used by the client in the original invoca- CORBA objects, these entities have In CORBA, objects frequently need to tion. state and methods; unlike CORBA call back or notify the client that invoked Policies allow control of quality of objects, they don’t (typically) have them; for this the objects act as clients and service of invocations. Clients and object references and are invoked in- the client-side module instantiates an objects may control ordering (by time, process as programming language object that’s called back in a reverse-direc- priority or deadline); set priority, dead- objects. It’s only when they’re included tion invocation. Because standard CORBA lines and time-to-live; set start and end in parameter lists of CORBA invoca- connections carry invocations only one times for time-sensitive invocations; tions that they show their talent by way, a callback typically requires a second and control routing policy and network packaging up their state in the sending TCP connection for this traffic heading in routing hop count. The specification context, sending it over the wire to the the other direction – a no-no to virtually also defines CORBA routers and store- receiving context, creating a running every firewall in existence. Under the new and-forward agents for IIOP invoca- instance of the object there and popu- specification, an IIOP connection is tions. Routers with the highest defined lating it with the transmitted state. Fre- allowed to carry invocations in the reverse quality of service will pass invocations quently used to represent nodes in direction under certain restrictive condi- with a transaction-like handshake and binary trees or cyclically linked lists, tions that don’t compromise the security at store invocations persistently, provid- valuetypes have been specified and either end of the connection. The firewall ing messaging-like network transmis- implemented to faithfully represent specification comprises two documents: sion. The routing specification defines these important constructs. This speci- www.omg.org/cgi-bin/doc?orbos/98-05- IDL interfaces to the marshaling fication gives CORBA the capability of 04 and an erratum, www.omg.org/cgi- engine, an interesting piece of work in the Java serializable, and is used exten- bin/doc?orbos/98-07-04 . itself. sively in both the reverse mapping and The URL for the messaging specifica- component model. The valuetype spec- Interoperable Naming Service tion is www.omg.org/cgi-bin/doc?or- ification may be downloaded from The CORBA object reference is a cor- bos/98-05-05. URLs www.omg.org/cgi-bin/doc?for- nerstone of the architecture. Because mal/99-07-09 and www.omg.org/cgi- the computer-readable IOR was (until Minimum, Fault-Tolerant and bin/doc?formal/99-07-10. Many aspects this service) the only way to reach an Real-Time CORBA of valuetypes show only in the language instance and invoke it, there was no way Minimum CORBA is intended pri- mappings; for these go to www.omg. to reach a remote instance – even if you marily for embedded systems. Embed- org/library/clangindx.html. knew its location and that it was up and ded systems, once they are finalized running – unless you could get access to and burned into chips for production, CORBA Components and CORBA its object reference. The easiest way to are fixed, and their interactions with the Scripting do that was to get a reference to its nam- outside network are predictable – they The CCM takes the key services you ing service, but what if you didn’t have a have no need for the dynamic aspects of use most regularly – persistence, trans- reference even for that? CORBA, such as the DII or the IR that actions, security and notification – com- The interoperable naming service supports it, which is why these features bines them with the POA’s servant-han- defines one URL-format object refer- are not included in minimum CORBA. dling capability, and wraps all these ence, iioploc, that can be typed into a The URL for the minimum CORBA tools in higher-level interfaces corre- program to reach defined services at a specification is www.omg.org/cgi- sponding to the patterns that experi- remote location, including the naming bin/doc?orbos/98-08-04. enced programmers use to code enter- service. A second URL format, iiop- Real-time CORBA standardizes re- prise and Internet server applications. name, actually invokes the remote nam- source control – threads, protocols, con- This means that: ing service using the name that the user nections and so on – using priority mod- • CCM applications are very compact. appends to the URL, and retrieves the els to achieve predictable behavior for They use little code, and the little IOR of the named object. both hard and statistical realtime envi- that’s required is devoted almost For example, an iioploc identifier, iio- ronments. Dynamic scheduling, not a totally to business programming. ploc://www.omg.org/NameService, part of the current specification, is being • Infrastructure functions – storing would resolve to the CORBA naming added via a separate RFP. The URL for data, activating and deactivating ser- service running on the machine whose the real-time CORBA specification is vants – are done automatically and IP address corresponded to the domain www.omg.org/cgi bin/doc?orbos/99- coded automatically as well. name www.omg.org (if we had a name 02-12; an erratum is www.omg.org/cgi- • CCM implementations will be built server running here at OMG). The URL bin/doc?orbos/99-03-29. around an industrial-strength infra- for the interoperable naming service Fault tolerance for CORBA is being structure written by specialists and specification is www.omg.org/cgi- addressed by an RFP, also in process, tuned for optimum performance in bin/doc?orbos/98-10-11. for a standard based on entity redun- stressed environments, including the dancy and fault management control. enterprise and Internet. When this Quality of Service Control The URL for all information on this RFP infrastructure runs your CCM appli- Asynchronous Messaging and Quality is www.omg.org/techprocess/meet- cation in its tuned environment, you of Service Control ings/schedule/Fault_Tolerance_RFP.ht automatically get the benefits – high The new messaging specification ml. throughput, great performance, 70 OCTOBER 1999 Java COM The Theory Center www.theorycenter.com OCTOBER 1999 71 Java COM C O R B A C O R N E R robustness – even though you don’t ments, event handling, multiple inter- To help build a market in components, have to write any infrastructure code, faces and navigation. The specification the CCM defines a software distribution or even code to POA and CORBA ser- covers all of the various ways that CORBA format with several notable features. The vices interfaces. clients can interact with EJBs and how distribution format contains executables Java clients can interact with CORBA for all of the platforms a vendor wants to The four major parts of the CCM are: components. We’ll go over details of these support, in a type of zip file. Installer • A model that presents common func- CCM/EJB interactions in a future col- code, built into the container, extracts tionality – transactions, security, umn. Since every container presents its and installs the proper executable for the event handling, persistence – to the services to components through the platform it’s going to run on. Following programmer at a high level using same set of standardized interfaces, com- installation, component executables can declarative languages and, optionally, ponent applications are portable from be configured. This overcomes another visual tools any vendor’s container to another’s. A resistance point – that it’s rare to find two • A container environment that pack- basic-level container packages up sub- installations that need exactly the same ages (at the basic conformance level) sets of the CORBA Transaction Service, piece of functionality. By building and transactions and security, adding (at CORBA security, and simple persistence selling flexible modules to wider markets, the extended conformance level) per- in a new set of interfaces. At level 2 the vendors can attain the volumes they sistence and event handling container adds more of the PSS and a need and the component market will • A software distribution format that subset of notification service. It’s not nec- build to critical mass. enables a CORBA component soft- essary for a container implementation to Configuration files contain informa- ware marketplace furnish its own persistence service; the tion on events emitted and consumed • Integration with Enterprise JavaBeans by components, at least at the extended level. Containers construct channels for Component model functions are ‘‘ the events and transmit them at run- packaged and presented to program- time. Since CCM applications typically mers at a higher level of abstraction than CORBA does as consist of several component types, the are the bare CORBA services. Compo- container will also have to connect up nent interfaces are declared using newly an invocation by one type to an inter- standardized additions to OMG IDL. much as it can to face on another; this also is specified in Components declare their persistent the configuration file and install-time state using Persistent State Definition configuration process. By the way, con- Language (PSDL, a superset of OMG support every figuration files use XML format. IDL), defined in the new PSS (a new There’s also a scripting language spec- CORBA service not presented here). Pro- ification that will map various scripting grammers then use Component Imple- languages to the CCM. This will add mentation Definition Language (CIDL, programming another way to assemble components an extension of PSDL) to declare some into applications, in addition to the of the component’s behavior; CCM XML-based assembly tools described in products use these declarations to gen- language and the CCM. We’ll devote a column to this erate code for parts of the implementa- sometime in the future too. tion. Finally, an XML-based configura- The CCM and scripting specifications tion language ties components together hadn’t completed their final votes when in assemblies and configures them for platform this column was written, but may be a individual installations. Because these done deal by the time you read it. Check new languages work at higher levels of out www.omg.org/techprocess/meet- abstraction than CORBA and the CORBA ings/schedule/CORBA_Component_M services, business programmers can specification assumes’’ that CCM prod- odel_RFP.html and www.omg.org/tech- write enterprise- and Internet-level ucts will use any standard PSS and that process/meetings/schedule/CORBA_Sc applications with less help (perhaps no your site administrator will buy and ripting_Language_RFP.html for details, AUTHOR BIO help!) from infrastructure experts. In install one. Of course, vendors are free to and to download your own copy of the Jon Siegel, Object addition, some of the languages were package PSS and CCM together if they 700-page CCM document. Management Group’s designed to be generated by visual tools. want. Level 1 containers must include director of technology One objective of CCM is to allow you to Transaction and Security support, how- Summing Up… transfer, presents tutorials, write distributed applications that mix ever, and level 2 containers have to add CORBA does as much as it can to sup- seminars and company CORBA components running in CORBA their own event handling capability. port every programming language and briefings around the component servers with EJBs running in Extended CORBA components sup- platform. Because Java’s object model world.The author of EJB-technology-based servers. This port multiple interfaces. The CCM aligns closely with CORBA’s, and Java’s CORBA 3 Fundamentals allows programmers to create an applica- defines interfaces, provided by the con- Virtual Machine is platform-portable, and Programming,he tion by reusing existing components of tainer, that allow a component-aware CORBA is able to do more with it than has extensive experience either kind. To accommodate EJBs the client application to navigate among with other languages, and this shows in in distributed computing, CCM defines two levels of containers and them. To component-unaware clients – the specifications we’ve reviewed in this object-oriented software conformance: the basic level container is including all clients written in a CORBA month’s column. We think this bodes development and transactional and secure, and provides 2 environment – each interface appears well for productivity and popularity on geophysical computing. simple persistence; its definition corre- to be an individual CORBA object; these both the CORBA and Java sides of the Jon holds a Ph.D. in sponds, almost feature for feature, to EJB clients can’t take advantage of the aisle, and I may muse more about it in a theoretical physical 1.1. To this the extended-level container implementation’s component nature future column. chemistry from Boston adds container-managed (and -imple- but can invoke it as a normal CORBA University. mented) persistence for multiple seg- object without any trouble. [email protected] 72 OCTOBER 1999 Java COM Protoview www.protoview.com OCTOBER 1999 73 Java COM Mindbridge.com Introduces IntraSmart Introducing the First SQL DB Written (Fort Washington, PA) – Mindbridge.com has in Java that Runs on Handheld released IntraSmart, a (San Mateo, CA) written in 100% Pure Java comprehensive, ready- – PointBase, has run on a handheld to-go intranet that Inc., and Psion device of any type. The includes powerful busi- Computers Psion-ready PointBase ness applications and announced suc- Mobile Edition is available the software components neces- cess running now with full Cerebellum Launches 1.3 sary to deploy an enterprise- PointBase developer (Pittsburgh, PA) – Cerebellum level intranet. IntraSmart’s busi- Mobile Edition on a Psion support. Software, Inc., released its next ness applications include Docu- Series 5mx handheld computer www.pointbase.com and upgrade, which enables a wider ment Sharing/Management, – the first time a SQL database www.psionusa.com variety of applications to easily Group Calendar/Scheduler, access, integrate and update Group Address Book/Company ObjectSwitch Offers Jeode Platform data located in an increased Rolodex and Employee Directo- EJB Interface Shines in number of data source types. ry. www.intrasmart.com (San Francisco, CA) – Performance The new version also provides ObjectSwitch Corporation Testing greater flexibility in the types of HOB Offers HOBLink announced its new EJB interface (Fremont, CA) – Insignia Solutions applications that can use Cere- J-Term 2.2 for ObjectSwitch 3. The announced that its Jeode Embed- bellum’s application program- (Dallas, TX) – Web-to-host con- ObjectSwitch ded Virtual Machine (EVM) tested ming interface. www.cerebel- nectivity is available using J-Adapter allows faster than other virtual machines lumsoft.com HOBLink J-Term version 2.2, a CLECs, Wireless evaluated in performance bench- Java-based terminal emulation Carriers and marks conducted by Pepsan Inc., Java Developer’s Journal software that offers 3270, 5250 alternative net- a third-party organization. Launches JDJ Consulting and VT525 connectivity among work providers to create intelli- www.insignia.com Services Division mainframe, midrange, UNIX and gent mediation and provisioning (Pearl River, NY) – In September personal applications using EJB servers JDJ Editor Gives Keynote 1999, Java Developer’s Journal computers. from multiple vendors, and to Speech at Hi-Tech Job Fair announced its new consulting HOBLink combine the resulting applica- (Meadowlands, services division, which will pro- J-Term pro- tions into a single seamless ser- NJ)– Sean Rhody, vide high-end, enterprise-wide vides secure, vice offering. editor-in-chief of Java technology solutions to mid- multiplatform, remote data www.objectswitch.com Java Developer’s sized and Fortune 500 corpora- access to mainframe, AS/400, Journal, was the tions. As the world’s leading Java UNIX and DEC computers via JavaCC Now Supported by keynote speaker resource, JDJ has been providing the Internet, intranets or Metamata at the cutting-edge Java solutions for extranets. www.hob.de (Fremont, CA) – career event at Giants Sta- over four years and is poised to Java Compiler dium on September 15, use its pool of expert Java devel- PalmSource ’99 Compiler (JavaCC), a parser 1999. JDJ was the exclusive opers to undertake mission-criti- Conference generator for use with Java media sponsor for this confer- cal Java projects. www. JavaDevel- (Santa Clara, CA) – applications, is now being dis- ence. opersJournal.com Palm Comput- tributed and supported by Earlier this year JDJ ing, Inc., will Metamata. In addition to the announced their Java career host its third parser generator, JavaCC opportunities services. annual provides other standard http://www.sys-con.com/ PalmSource capabilities related to parser java/jobs/javajobs.cfm Your Key to Java Experts conference generation such as tree for the Palm building, actions, debugging, Computing plat- etc. www.metamata.com SilverStream Announces J2EE form on October 19–22, 1999, at the Santa Clara Conven- ServletExec 2.1 and Seminars tion Center. The conference will ServletExec Debugger 2.1 (Burlington, MA) – educational provide attendees with platform (Alpharetta, GA) – New Atlanta SilverStream Software, materials, techni- technology presentations, Communications, LLC, Inc., has launched a cal demonstra- industry perspectives and prod- announces Servlet Exec 2.1, a worldwide educational tions and instruc- uct showcases. Sponsors include free upgrade to its servlet and seminar series designed tion from indus- Aether, AvantGo, BellSouth, JSP engine, and the ServletExec to educate Java applica- try experts. For Handspring, IBM, JP Systems, debugger tion developers and seminar informa- Motorola, QUALCOMM, Sun 2.1, a free architects on J2EE. Beginning tion and registration go to Microsystems and Symbol Tech- tool for in October, the free half-day www.silverstream.com/web- nologies. Participants can regis- developing and debugging “J2EE for the Real World” ses- site/SilverStream/Pages/event ter online, via fax or by mail. servlets within popular Java sions will include software, s_f.html. www.palmsource.com IDEs. www.newatlanta.com 74 OCTOBER 1999 Java COM InetSoft www.inetsoftcorp.com OCTOBER 1999 75 Java COM Pervasive Software has released version 7.5 KEY of its ubiquitous database engine and software Driver Class SQL 2000 v7.5 development kit. I got the chance to take a Producer Base look at the database and the various tools Session SCursor using an evaluation copy of the software for Produced Derived by Windows NT 4.0. Pervasive Software Installation and Configuration Database XCursor BufferMetaData I installed the software from the Perva- REVIEWED BY JIM MILBERY siveSQL 2000 SDK CD-ROM. Pervasive Table TableMetaData BufferMetaData automatically searches for the presence of a working copy of their workgroup data- IndexMetaData BufferMetaData base engine when you install the SDK kit. If you don’t have a running copy of Perva- siveSQL, the SDK will install the database RowSet SCursor server kit first. The install routine for the database server gives you the choice of accepting a typical installation or select- XCursor ing a custom install option. Selecting the BufferMetaData custom install for the database server PsqlException XCursor appears to make no difference; the AUTHOR BIO installation program seemed to go Jim Milbery is a software consultant with Kuromaku Partners ahead and install all the options anyway. FIGURE 2 Pervasive Java API LLC. He has over 15 years of experience in application All in all the installation went smoothly. development and relational databases. Jim can be reached After the installation completes, the is easy and quick. Pervasive has essentially at [email protected], or via the company Web site server runs a small test to ensure that built its relational database-access layer at www.kuromaku.com. everything was installed properly. around the ODBC standard, making it a [email protected] Once the database is running, the SDK straightforward process for embedded devel- kit can be installed. Selecting the custom opers to work with the relational layer. SQL 2000 v7.5:Pervasive Software option for the SDK gives you a number of Although you’re free to develop all your appli- Web:www.pervasive.com choices. PervasiveSQL 2000 provides a cations using the relational layer, the folks at Phone:800.287.4383 comprehensive set of tools for interfac- Pervasive make no bones about the fact that ing with the database, such as plug-ins one of its advantages is the ability to use the Test Environment: for Inprise, Microsoft Visual Studio and transactional interfaces to access the database Java. The database server is available for at a much lower level. On their Web site, Perva- Client/Server:Gateway Solo 366,256MB RAM, Windows NT and Novell NetWare, and sive provides a detailed description of their 10 Gigabyte disk drive, Pervasive has announced versions for product in a paper called “Pervasive Products Windows NT 4.0 (Service Pack 4) Solaris and Linux. Pervasive even makes and Services,” where they describe what they a version of the engine available for vari- believe to be some of the major benefits of the Pricing:$149.00 ous smart-card environments. transactional interface, e.g., speed, data integrity and scalability. Although the original Architecture Requiremnts: Btrieve API is over 15 years old, it continues to The database server uses a small foot- evolve. Thus it supports modern RDBMS con- Intel 486,Windows NT 4,95 or 98, print and starts up easily and quickly as cepts such as transaction support and on-line 29 MB hard Disk an NT service. The underlying tech- backup, which are more commonly identified 6 MB RAM nique that serves as the foundation for with relational database engines. A single “log- PervasiveSQL 2000 is an engine that Per- ical” database can be accessed by the lower- vasive calls the MicroKernel Database level transactional APIs as well as by ODBC and Engine (MKDE). The MKDE provides a SQL. The Pervasive Control Center provides core layer for all low-level processing, you with tools to add the necessary data dictio- such as index management, caching, nary information to a set of Btrieve files that transaction control and lock manage- form a logical database. If you wish to access PRODUCT REVIEW PRODUCT REVIEW ment. The PervasiveSQL engine is built the database using the transaction interface, on top of the MKDE with a transaction they provide a suite of ActiveX controls for this layer based on Pervasive’s Btrieve archi- purpose, as well as interfaces for Visual Basic, tecture, and a relational layer based com- Delphi and C++. PervasiveSQL also provides an pletely on ODBC. Pervasive’s SQL interface interface from Java that’s based on JDBC, but is abstracted from the MicroKernel by a they’ve added some extensions to account for layer that’s called the SQL Relational Data- the fact that JDBC is based upon SQL, which base Engine (SRDE) (see Figure 1). isn’t a requirement for the Btrieve API layer. Part of Pervasive’s differentiation from the This allows a Java program to access the Btrieve other database players in the marketplace is API directly, without relying on column infor- Core Engine Function their support of relational and transactional mation stored in the relational layer. Current *Physical Data Access *Transaction Processing interfaces based on their Btrieve layer. Perva- Btrieve programmers will find that the Java *Caching *Data Integrity Enforcement *Concurrency sive’s relational interface fully supports the interface hides many of the implementation ODBC standard (and by extension JDBC), and details when compared with the older non-Java FIGURE 1 Pervasive MicroKernel Architecture programming against the MKDE using ODBC API. 76 OCTOBER 1999 Java COM Java Buyers Guide www.javabuyersguide.com OCTOBER 1999 77 Java COM Pervasive SQL and Java between them is somewhat inconsistent. Many I found the Java interface reasonably easy to of the utilities provide for making detailed use. Pervasive provides documentation for modifications at the lowest levels of the data- working with their sample applications in base, and the utility interface expects you to either Inprise’s JBuilder or Symantec’s Visual know what you’re doing. For example, the Cafe. However, I was able to work with the sam- Maintenance utility gave me low-level access ple projects using my copy of Oracle JDevelop- to the UGRADS file that I created inside my er. Pervasive makes use of the factory concept new database. However, the utility assumed for their Java API, as shown in Figure 2. that I knew what I wanted to do to the file, and There are class objects for the major tasks there were no wizards to guide me through the you’ll need to undertake in order to work with modification process. your PervasiveSQL database and Java. What Once my database was created, it was a rela- makes Pervasive different from working direct- tively simple process to use the Java API to ly with JDBC is you can also access the data access my UGRADS table through a Java pro- using the transactional API. If you have a logi- FIGURE 3 Pervasive Control Center gram (although I’ll admit that I stuck to using cal database that includes a relational data dic- the relational layer with the DATABASE class). tionary layer, you can use the DATABASE class ter. I was easily able to create a new database to work with the metadata, as in a classical with a relational layer using the ODBC inter- Summary relational design. However, you’re not required face from the control center. I modified a few The Pervasive Software Web site offers an to use this interface in order to access the existing table-and-load scripts and used them Aberdeen research paper that compares the Btrieve layer. The Java API will allow you to with the SQL Query window to create a new total cost of ownership of PervasiveSQL to work directly with data files in a loosely cou- table and populate it with data. The control other database engines on the marketplace. pled database. The standard installation of Per- center provides a classic text display as well as Given the fact that you can control the entire vasive includes a number of sample databases a grid display for records, as shown in the panel database and server through the API interface, and programs for you to work with. As usual, I on the right-hand side of Figure 3. Pervasive I believe you can build an application and bypassed the samples and went directly to cre- provides plenty of tools and utilities for work- database that’s easy to maintain and manage. If ating my own database using the Pervasive ing with the server engine as well as the data- you plan on embedding a database inside an Control Center, as shown in Figure 3. bases managed by the server. Pervasive’s API application and are willing to control the data- The control center provides a one-stop-shop supposedly allows you to control and tune your base in this manner, Pervasive offers a com- for accessing all the major tools and interfaces databases as well as access records, and I sus- pelling product. Pervasive will appeal to the for creating and managing Pervasive databas- pect that the development team made use of developer who wants to exert a fine degree of es. There are lots of hidden gems within the this API when constructing the various utilities control over the data while still allowing end various tools that are shown in the outline con- that are called by the control center. There are users to access the underlying data using trol on the left-hand panel of the control cen- an abundance of tools, but the user interface friendly SQL interfaces over ODBC. Cyscape www.cyscape.com 78 OCTOBER 1999 Java COM Get Your Own Subscription to the Finest Technical Journals in the Industry! 1-800-513-7111 www.sys-con.com SYS -CON PUBLICATIONS Only Java Developer’s Journal Readers are 100% Pure Java PUBLICATIONS REGULARLY READ BY JAVA PROFESSIONALS Your ad in Java Developer’s Journal reaches only 100% Java professionals who make the decisions to purchase Java related Before you products and services, not Visual Basic programmers who never advertise in a publication, please Carmen requested the publication you advertise in! Gonzalez ask how many Vice President, JDJ Advertising We build our circulation one subscriber at a time. real Java readers Sales 84% you’re actually That’s one of our secrets why your ad works in JDJ. reaching! 39% Independent Readex Reader Survey results 18% 3% JDJ Java Report Java World JavaPro www.JavaDevelopersJournal.com or call 914-735-0300 ©1999 SYS-CON Publications, Inc. All rights reserved. The World’s Leading Java Resource JDJ and Java Developer’s Journal are registered trademarks of SYS-CON Publications, Inc. All other names are trademarks of their respective owners. Java COM Java COM Sigs Java C www.javad Conference evcon.com OCTOBER 1999 81 Java COM ind the most u f qu yo al n if a ie c d d l J r a o v w a e e h x t p e n r t i s e f r o e r h W y o u r e n t e r p r i s e J a v a t e c h n o l o g y s ol ut i o ns ? Your Key to Java Experts www.javadevelopersjournal.com [email protected] Java COM ADVERTISINGINDEX ADVERTISER URL PH PG 9NETAVENUE, INC. WWW.9NETAVE.NET 888.9NETAVE 63 AMERICAN CYBERNETICS WWW.SOFTEXPORT.COM 800.899.0100 55 AVANTSOFT, INC. WWW.AVANTSOFT.COM 408.530.5705 83 BEA WEBLOGIC WWW.WEBLOGIC.BEASYS.COM 800.817.4BEA 2 BLUE SKY SOFTWARE WWW.BLUE-SKY.COM 800.559.4423 23 CAREER CENTRAL WWW.CAREERCENTRAL.COM/JAVA 888.946.3822 60 CAREER OPPORTUNITY ADVERTISERS 800.846.7591 85-93 CEREBELLUM SOFTWARE WWW.CEREBELLUMSOFT.COM 888.862.9898 37 Advantsoft COMPUWARE NUMEGA WWW.COMPUWARE.CON/NUBEGA 800.4.NUMEGA 6 CYSCAPE WWW.CYSCAPE.COM/FREE4J 800.932.6869 78 DEVELOPMENTOR WWW.DEVELOP.COM 800.699.1932 83 ELIXIR TECHNOLOGY WWW.ELIXIRTECH.COM/ 65 532.4300 51 ENTERPRISESOFT WWW.ENTERPRISESOFT.COM 510.742.6700 11 FIORANO SOFTWARE, INC. WWW.FIORANO.COM 408.354.3210 33 www.avantsoft.com FORCE 5 SOFTWARE, INC. WWW.FORCE5.COM 408.735.0665 53 GEEK CRUISES WWW.GEEKCRUISES.COM 67 IAM CONSULTING WWW.IAMX.COM 212.580.2700 61 INETSOFT TECHNOLOGY CORP WWW.INETSOFTCORP.COM 732.235.0137 75 INSIGNIA SOLUTIONS, INC. WWW.INSIGNIA.COM 800.848.7677 57 INSTANTIATIONS INC. WWW.INSTANTIATIONS.COM 800.808.3737 26 JAVA BUYER’S GUIDE WWW.JAVABUYERSGUIDE.COM 914.735.0300 77 JDJ CONSULTING SERVICES WWW.JAVADEVELOPERSJOURNAL.COM 800.713.5111 84 JAVA DEVELOPER’S JOURNAL WWW.JAVADEVELOPERSJOURNAL.COM 914.735.0300 79 JDJ STORE WWW.JDJSTORE.COM 888.303.JAVA 42-43 KL GROUP INC. WWW.KLGROUP.COM/PAGELAYOUT 888.328.9599 67 KL GROUP INC. WWW.KLGROUP.COM/SWINGSUITE 888.328.9596 21 KL GROUP INC. WWW.KLGROUP.COM/COLLECT 888.3289597 96 METAMATA, INC. WWW.METAMATA.COM 510.796.0915 45 NEW ATLANTA WWW.NEWATLANTA.COM/ 678.366.3211 29 OBJECT DESIGN WWW.OBJECTDESIGN.COM/JAVLIN 800.962.9620 48-49 OBJECT INTERNATIONAL SOFTWARE WWW.OI.COM 919.772.9350 39 OBJECTSWITCH CORPORATION WWW.OBJECTSWITCH.COM 415.925.3460 35 PALM COMPUTING, INC. WWW.PALM.COM 69 POINTBASE WWW.POINTBASE.COM/DEVLIC/JDJ 877.238.8798 27 PROTOVIEW WWW.PROTOVIEW.COM 800.231.8588 3 PROTOVIEW WWW.PROTOVIEW.COM 800.231.8588 73 QUICKSTREAM SOFTWARE WWW.QUICKSTREAM.COM 888.769.9898 30 Develop RIVERTON SOFTWARE CORPORATION WWW.RIVERTON.COM 781.229.0070 47 SD 99 EAST WWW.SDEXPO.COM 800.441.8826 82 SEGUE SOFTWARE WWW.SEGUE.COM 800.287.1329 17 SIGS CONFERENCE FOR JAVA DEVELOPMENT WWW.JAVADEVCON.COM 212.242.7515 80-81 SILVERSTREAM SOFTWARE, INC. WWW.SILVERSTREAM.COM 888.823.9700 95 SL CORPORATION WWW.SL.COM 415.927.1724 59 Mentor SLANGSOFT WWW.SLANGSOFT.COM 972.375.18127 16 SLANGSOFT WWW.SLANGSOFT.COM 972.375.18127 56 SOFTWIRED INC. WWW.JAVAMESSAGING.COM (41) 1.445.2370 7 SUN MICROSYSTEMS INC. WWW.SUN.COM/SERVICE/SUNED/JAVA2 800.422.8020 4 SYBASE INC. WWW.SYBASE.COM 800.8.SYBASE 25 THE THEORY CENTER WWW.THEORYCENTER.COM 888.843.6791 71 www.develop.com/courses/ijava.htm TIDESTONE TECHNOLOGIES WWW.TIDESTONE.COM 800.922.9665 31 UNIFY CORPORATION WWW.EWAVECOMMERCE.COM 800.GO.UNIFY 13 VISICOMP, INC. WWW.VISICOMP.COM 831.335.1820 15 VISUALIZE INC. WWW.VISUALIZEINC.COM 602.861.0999 66 VSI WWW.VSI.COM/BREEZE 800.556.4VSI 41 WORLDWIDE INTERNET PUBLISHING WWW.WIPC.NET 800.785.6170 65 OCTOBER 1999 83 Java COM Java Business Conference www.javabusinessconference.com 84 OCTOBER 1999 Java COM Career Opportunities OCTOBER 1999 85 Java COM Career Opportunities 86 OCTOBER 1999 Java COM Career Opportunities OCTOBER 1999 87 Java COM Career Opportunities 88 OCTOBER 1999 Java COM Career Opportunities OCTOBER 1999 89 Java COM Career Opportunities 90 OCTOBER 1999 Java COM Career Opportunities OCTOBER 1999 91 Java COM Career Opportunities 92 OCTOBER 1999 Java COM IMI Systems Inc. www.imisys.com OCTOBER 1999 93 Java COM IMHO Java OOP Means OODBMS—“Not” WRITTEN BY BRUCE SCOTT here are many reasons for Java’s success. tremendous marketeer and has managed to fool us all?” Larry is Although heavily debated and discussed, the good but not that good. The answer may be too simple to believe. “Write Once Run Anywhere” aspect of Java is The relational model has stood the test of time simply because it’s one of the reasons. A sometimes less-heralded good. Most of the world’s data isn’t terribly interesting or complex reason is Java’s superior object-oriented and fits quite nicely into simple rows and columns. The complexity Timplementation. I don’t view myself as an OO comes from the ever-evolving use of the data. RDBMS with SQL expert, but I’ve observed the rapid market acceptance of Java as allows the use of the data to evolve in unpredicted ways. Yes, there compared to other OO languages. In the past these languages took are special situations where an OODBMS approach works best, such many years to enter the mainstream (C++) or remained in a niche as parts explosions, CAD or mapping. These special cases can now market (SmallTalk). The creators of Java were able to stand on the be solved with OO extensions to the relational model found in the shoulders of others that had created OO languages; they were able to SQL ’99 standard or with object-to-relational mapping tools. capitalize on the tremendous strength of OO programming and There are many reasons for the success of RDBMS over OODBMS. avoid the pitfalls. With Java, they created a language and platform Unlike OODBMS the data relationships don’t have to be decided that’s allowing OOP to rapidly enter the mainstream. ahead of time. As the uses of data evolve the RDBMS can adapt With my background in database technology, I’ve seen similar sea through the support of joins and other dynamic aspects of SQL, and changes in databases. Before relational databases there were network by easily altering the relational schema. SQL provides an industry- and hierarchical databases. Relational databases were the new kid on wide standard for accessing and managing data. There’s no equiva- the block, and it took Oracle’s success to show that these early data- lent industry-accepted query language for OODBMS. One must base models could be replaced. In the mid to late eighties, some write a procedural program for every new use of the data. The believed that relational databases would be RDBMS market is supported by a large after- replaced by another model – object-oriented market that includes application development databases. In Silicon Valley hundreds of mil- tools, report generators, design tools, etc. No lions of dollars were invested in OODBMS ‘‘ such aftermarket exists for the OODBMS mar- start-up companies. In the last ten years the Why has RDBMS ket. The list could go on. market has made an overwhelming choice. We all want Java to succeed and it will. Java’s Today RDBMS is a multibillion-dollar ($10 bil- maintained a success will grow as we bridge Java to the high- lion+) market and OODBMS is only a $200–300 ly successful RDBMS market. Java OODBMS million market. OODBMS companies have dominant position applications will find themselves in the found themselves relegated to a niche market OODBMS niche. These applications will only providing very specialized solutions. for over 20 years? detract from the momentum of Java because Now with Java and OOP entering the main- they’ll be isolated. stream the proponents of OODBMS are hang- Is it because At PointBase we strongly believe in this, so ing their hat on promoting the belief that OOP we want to help every Java programmer learn requires an OODBMS. They’re hoping that Larry Ellison is a how to write Java applications that use an Java programmers will believe that the same RDBMS. On our Web site is a free developers’ advantages that are derived from OOP will tremendous version of our 100% Pure Java database. A Java also come from using an OODBMS. programmer can get up and running in min- What’s missing here is that one of Java’s marketeer and utes and try their hand at developing an strengths is its ability to connect the old world RDBMS application. It’s compatible with Ora- with the new. The new world includes appli- has managed to cle but doesn’t require the complexities or cation servers, mobile computing and Inter- expense of buying and installing Oracle. We net devices. The old world contains a vast fool us all? encourage Java programmers to download this amount of relational data, among other free PointBase developers’ version so they can things. Sun has spent a lot of effort on JDBC learn how to use RDBMS with Java. On our Web because they understand the importance of site we also host Developers Central to help providing Java programmers with the ability to access the vast’’ answer questions on how to build RDBMS applications in Java. In amount of relational data available. With JDBC Java programmers our own way we’re doing our part to help Java succeed by connecting can access all the world’s relational data, and as they move from pro- Java to the lucrative world of relational data. ject to project, or job to job, the skills they acquire in working with an RDBMS are easily transferred. Contrast this with working on a pro- AUTHOR BIO ject that uses an OODBMS. The likelihood that the next project or job Bruce Scott, president, CEO and founder of PointBase, is a leader in the area of enterprise and will use an OODBMS are about 100 to 1 based on the relative market embedded database architecture and product development. A cofounder of Oracle in 1977, Bruce sizes. Since OODBMSs are in a niche market, the Java programmer cofounded Gupta Technology in 1984, pioneering the notion of the small footprint database server for who spends time on an OODBMS application will be too. Intel-based platforms. The question to be asked is: “Why has RDBMS maintained a dom- inant position for over 20 years? Is it because Larry Ellison is a [email protected] 94 OCTOBER 1999 Java COM Silverstream www.silverstream.com OCTOBER 1999 95 Java COM KL Group www.klgroup.com/collect 96 OCTOBER 1999 Java COM