COM+ Component-Based Computing Environments

Home , Active Platform, Common Type System, Component Object Model, Windows API, XSP (software)

Application Servers G22.3033-011

Session 10 - Main Theme .Net/COM+ Component-Based Computing Environments

Dr. Jean-Claude Franchitti

New York University Computer Science Department

Courant Institute of Mathematical Sciences 1

Agenda

Web-Enabling Facilities (continued)

Java Web Start (JWS)

COM / DCOM Component Model and OLE

COM+ MTS Services: Transactions and Security

COM+ Message Queuing

.Net/COM+ Integrated Services

Enterprise Component Development with .Net/COM+

Designing .Net/COM+ Component-Based Architectures

Summary

Readings

Assignment #7 (continued) 2

1 Summary of Previous Session

J2EE Client Component Infrastructures (continued)

CORBA 3 OMA Services

CORBA 3 CCM

CORBA 3 Environments

Enterprise Component Development with CORBA 3

Designing CORBA 3 Component-Based Architectures

Summary

Readings

Assignment #7

Application Servers Architectures

Application Servers for Enhanced HTML (traditional)

a.k.a., Page-Based Application Servers

Mostly Used to Support Standalone Web Applications

New Generation Page-Based Script-Oriented App. Servers

First Generation Extensions (e.g., Microsoft IIS with COM+/ASP)

Servlet/JSP Environments

XSP Environment

Can now be used as front-end to enterprise applications

Hybrid development environments

Distributed Object Computing Platforms

Provide an infrastructure for distributed communications enabling

Still need to merge traditional web-oriented computing with object computing

Object Management Architectures

DOC Platform + APIs to reusable services and facilities 4 OMAs+Client/Server Component Models -> J2EE, CCM, DNA

2 CORBA 3 References

OpenCCM Documentation

http://openccm.objectweb.org/doc/index.html

Getting started with OpenCCM Tutorial

http://openccm.objectweb.org/doc/0.5/tutorial_Getting_Started_with_OpenCCM.ppt

OpenCCM Installation Guide

http://openccm.objectweb.org/doc/0.8/install_guide.html

OpenCCM 0.8 Download

http://openccm.objectweb.org/download/index.html

Part I

Microsoft Platform Architectures (includes slides covered in previous sessions)

Also See: “http://www.execpc.com/~gopalan/misc/compare.html” “http://www.javacoffeebreak.com/articles/rmi_corba/” “http://www.quoininc.com/articles.html”

3 Microsoft Active Platform (Logical Architecture)

Microsoft Active Platform (Features)

Logically centralized architecture

Physically de-centralized architecture

Scripting

Client-Side: Improved user interface and data validation

Server-Side: Business rules and data access

VBScript and JavaScript built-in support

PerlScript support via ActiveX scripting engine (e.g., ActiveState’s)

Ability to mix scripting languages

Active Server Components

Provide OS services to ASPs

Encapsulate business rules to ease programming

e.g., TextStream Component (FileSystem object) 8

4 Microsoft Active Platform (Physical Architecture)

Microsoft Component Object Model (Logical Architecture)

5 11

6 13

7 15

COM IDL (stockMarket.idl)

Example: [ uuid(7371a240-2e51-11d0-b4c1-444553540000), version(1.0) ] library SimpleStocks { importlib("stdole32.tlb"); [ uuid(BC4C0AB0-5A45-11d2-99C5-00A02414C655), dual ] interface IStockMarket : IDispatch { HRESULT get_price([in] BSTR p1, [out, retval] float * rtn); }

8 COM IDL (continued)

Example: [ uuid(BC4C0AB3-5A45-11d2-99C5-00A02414C655), ] coclass StockMarket { interface IStockMarket; }; };

9 19

DCOM Architecture Review

10 DCOM Object Activation/Method Invocation (top layer - basic programming architecture)

DCOM Object Activation/Method Invocation (middle layer - remoting architecture)

11 DCOM Object Activation/Method Invocation (bottom layer - wire protocol architecture)

12 COM+

See Session 4:

Sub-Topic 3 Presentation on Introduction to CORBA, DCOM, and RMI

See Session 5:

Sub-Topic 3 on Introduction to .Net/C#

Sub-Topic 4 on Building COM+ Applications

COM+ = DCOM/COM + MTS

13 DNA Web Architectures

FORM+ = Merger of Win32 GUI and Web APIs (~DHTML)

STORAGE+ = OLE DB

COM+ = COM + MTS 27

Distributed InterNet Applications Architecture (DNA)

14 Microsoft DNA Environment (summary)

See comparison of EJB and MTS models:

http://members.tripod.com/gsraj/misc/ejbmts/ejbmtscomp.html

Environment combines

COM+ (DCOM+MTS) Component Model

Win32/SCM and DCOM/COM+ Services

Visual Studio Development Environment

Microsoft IIS with COM+/ASP Features IDE:

Visual InterDev (ASP)

Management of site development process

Scripting

Alternative IDEs

Macromedia Drumbeat, Ultradev, Dreamweaver

NetObjects Fusion

Microsoft FrontPage 2000

Adobe GoLive

Server Platforms

Windows 2000/NT

Use ChiliSoft for other platforms (http://www.chilisoft.net/)

Platforms: Solaris, Linux, AIX, HP-UX, Windows

Immunity from current IIS attacks (e.g., code red worms on Win 2000)

Web Server: Apache, iPlanet

Chili!Beans support for Java (similar to Microsoft with COM+ and ASP for C++) 30

15 Microsoft IIS with COM+/ASP Features

See “Microsoft IIS, COM+, and ASP” in “Web Server Brains”

COM+ / ASP

Equivalent to J2EE EJB / JSP

Included in Microsoft Windows 2000 Advanced Server

COM+

Attributes (declare what runtime services are needed by the component)

Threads and database connection pools (access via Active Data Object API)

ASP Object Model sub-systems

HTTP request

COM+ transaction

External COM+ components

Other solution components:

Visual Studio 6.0

Internet Security and Acceleration Server (ISA)

static content caching, fault tolerance, load balancing, request handling 31

Microsoft .NET Platform Smart Devices + Windows XP + Web Services

http://www.microsoft.com/net

First set of Microsoft Web Services

http://www.microsoft.com/net/hailstorm.asp

16 Part II

Win32 and COM+ Services (includes slides covered in previous session and new ones)

“http://members.tripod.com/gsraj/misc/ejbmts/ejbmtscomp.html and related archives”

and Session 10 Sub-Topic 1 Presentation on “A COM+ Application Scenario”

DNA OMA Services

Activation Services

DCOM Activation Framework

Naming and Directory Service

DCOM Class and Object Naming (i.e., CLSIDs, ProgIDs, and Monikers)

Trading Service

Microsoft Active Directory

Transaction Service

COM+ MTS

Messaging Service

COM+ MSMQ

17 Win32 Services

Win32 executable that satisfy several properties

Lifetime is controlled by the Service Control Mgr (SCM)

Service is registered with SCM, and understands and obeys SCM commands

Service has its own login session or shares one with another service

Service runs as a user or local system and abides to applicable security

Service implements a set of service-specific functions:

Starting up, message handler, communication back to SCM

COM+ Services

COM+ Catalog (v.s. Windows Registry)

COM+ Load Balancing

COM+ In-Memory Database (IMDB)

COM+ Object Pooling

COM+ Queued Components

COM+ Events

C++ Compiler Changes

18 DCOM Class and Object Naming (file moniker file: bind)

DCOM Class and Object Naming (url moniker http:, ftp:, gopher: bind)

19 DCOM Class and Object Naming (class moniker clsid: bind)

Display name for class monikers: display-name = "CLSID:" string-clsid-no-curly-braces *[";" clsid-options] ":" clsid-options = clsid-param "=" value clsid-param = none currently defined

C++ example (tell moniker to use an object that can read a document instead of the document itself): ProgIDFromCLSID( &clsid, "xyz.activator.1") CreateClassMoniker( clsid, &pmkClass ) MkParseDisplayName( pcb, "\\northamerica\central\employee.doc", &dwEaten, pmkFile ) pmkFile->BindToObject( pcb, pmkClass, IID_IDispatch, &pDisp ) 39

COM+ Catalog v.s. Windows Registry

Stores COM+ application attributes, class attributes, and computer-level attributes

Guarantees consistency among attributes

Provide common operations on top of attributes

Two different stores

COM+ registration database

Microsoft Windows Registry (HKEY_CLASSES_ROOT)

COM components that do not require new COM+ services

Type library

Interface proxy/stub registration

Unified logical view via COM+ Admin Library 40

20 Microsoft Active Directory

Maintains user, security, and network resource information used on a Windows 2000 network DCOM components can store their activation and connection information in the ADS COM objects can be exposed as APIs to ADS

Trading Service - Active Directory http://www.microsoft.com/windows2000/server/evaluation/features/dirlist.asp

21 COM+ Load Balancing

COM+ IMDB

22 MSMQ Messaging

Upon queued component instantiation

Local recorder proxy object is created

As the client makes method calls

Local recorder object serializes the calls into MSMQ messages

Client commits the object by releasing all references to it

Message is passed to the server via MSQM

Special service running on the server de-queues messages and instantiate the component using a player proxy

Upon failure

A message is placed back on the queue

Getting back to the client

No response needed

Response queues (asynchronous reporting) 45 Pass by value interface references

COM+ Queued Components

23 Using COM+ Queued Components Svc.

Example:

IOrder* pOrder = 0; CoCreateInstance( CLSID_Order, ... IID_IOrder, (void**) &pOrder );

pOrder->put_Customer( 2000 ); pOrder->put_Quantity( 2 ); CComBSTR bstrSKU( "3535-2334" ); pOrder->put_SKU( bstrSKU );

long lOrderNumber; pOrder->Submit( &lOrderNumber ); pOrder->Release(); 47

COM Event Handling Mechanisms

Events/Callbacks via client interface

Client implements an interface defined by the component

Uses Advise/Unadvise methods (see example in later slide)

Events/notifications are handled via calls through the client interface

Connectable Objects via COM Events model

Uses standard COM IConnect-ionPoint interfaces

Includes runtime recovery and minimal multi-casting capabilities

Objects play the role of publishers/subscribers

No support for persistent connection

Overall complex Event model to use

COM+ Events model

Introduces an event class object to decouple publisher and subscriber 48

24 COM+ Events

Using COM+ Events

COM Event Model: // Our event interface interface IMyEvents : IUnknown { HRESULT SomethingHappened( BSTR bstrWhat ); } // An interface on our component interface ISomeInterface : IUnknown { ... HRESULT Advise( IMyEvents* pIEvents ); HRESULT Unadvise(); }

COM+ Event Model: interface IEventClass : public IDispatch { HRESULT put_EventClassID( BSTR bstrEventClassID ); HRESULT put_EventClassName( BSTR bstrEventClassName ); HRESULT put_FiringInterfaceID( BSTR bstrFiringInterfaceID ); ... }; 50

25 C++ Compiler Changes

Sample Attributes:

in/out direction of parameter in a method

threading model

component housing (i.e., DLL or EXE) 51

Creating an MTS Component

Example:

try {

// create the MTS component bank.IChecking server= (bank.IChecking) new bank.Checking ();

// invoke business methods on the component server.createAccount (1234, "Athul", 1000671.54d); } catch (Exception ex) { ex.printStackTrace (); }

26 .NET Framework

Common Language Runtime (CLR)

Accessible to any compiler that produced Microsoft Intermediate Language (IL) code

Runtime Classes

Visual Studio.Net (VS.Net)

Includes VB.Net, VC.Net (C#), and Visual C++.Net

.NET, Win32, COM, and COM+

.Net applications can call functions that reside in Win32 DLLs via the DllImport attribute of System.Runtime.InteropServices’ platform invocation (PInvoke) services

.Net applications can call traditional COM components using Runtime Callable Wrappers (RCWs) which uses interop assemblies (i.e., .Net components) created via COM Interop using the TLBIMP utility

COM+ services (transactions, object pooling, JIT activation) can be used from .Net (via System.EnterpriseServices namespace)

.Net runtime uses COM+ to support some of its services (e.g., transactions for managed classes) 54

27 .Net Remoting (http://www.dotnetremoting.cc/)

Native .Net Remote Object Invocation

Allows Object Invocation and Communications Across Processes and Machines

Wire Protocol and Format Independent

Extensible via Custom Formatters (SOAP, Binary, etc.), Channels (HTTP, TCP, etc.), and Sink Chain (i.e., Channels + Formatters) Steps

Flexible as Configuration can be Changed after Deployment with Little or no Code Changes

Flexible (IIS not required on server) but more Complex than Web

Services 55

.Net Remoting Vs. DCOM

Not as Transparent as DCOM

Has no COM Interop Involved

Offers More Deployment Options

Not Tied to a Specific Wire Protocol or Format

Firewall Friendly

Allows you to Specify which Objects are Remoted

28 .Net CLR and COM+

CLR Introduces a Newer and Easier Programming Model for COM+

The COM+ Services are still Available only at the OS/Unmanaged World

Transitions Between Managed/Unmanaged Layers are Taken Care of by “System.EnterpriseServices” Namespace

System.EnterpriseServices.ContextUtil class provides access to contexts (as did CoGetObjectContext)

Services are Made Available to Components Using Attributes 57

ContextUtil Class

Useful Static Members

ActivityId

IsSecurityEnabled

TransactionId

DesactivateOnReturn

MyTransactionVote

Rich Set of Member Functions

SetComplete

SetAbort

EnableCommit

DisableCommit

IsCallerInRole

GetNamedProperty 58

29 .Net and ServicedComponent

COM+ Class Derives from “ServicedComponent” [ComVisible(true)] [ObjectPooling(MinPoolSize=2, MaxPoolSize=5)] [Guid(“57F01F20-9C0C-4e63-9588-720D5D537E66)] [Transaction(TransactionOption.Required)] public class SVCCompClass : ServicedComponent

In COM+ 1.0, the List of Services Are not Changed

In COM+ 1.5 (Microsoft Windows XP Professional and .Net server), Newer Services are Available to Leverage CLR Features

Component Layers in .Net Applications/Services (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/distapp.asp)

30 Security Policies in .Net Applications/Services

Operational Mgmt Policies in .Net Applications/Services

31 Communication Policies in .Net Applications/Services

.Net Applications Support Technologies/Services (continued)

Security, Operational Management, Communication provided by Microsoft Windows OS Services

Active Directory Service

Message Queuing

Windows Management Instrumentation (WMI)

etc.

32 .Net Applications Support Technologies/Services

Part III

COM+ Application Scenario

See Session 4 Sub-Topic 1 on “Distributed Communications Enabling”

33 Part IV

Enterprise Component Development with .Net/COM+ (See Intro to C# at: http://www.ecma- international.org/activities/Languages/Introduction%20to%20Csharp.ppt, overview of .Net at http://www.enterprise-component.com/docs/WebServWs.ppt and http://www.enterprise-component.com/docs/WebServWs.ppt)

Application Platforms Today

Browser Web Services Local Other Apps Apps Apps Apps

GUI Transaction Web Data Remote More Services Services Scripting Access Access Standard Library

Runtime Environment

Operating System 68

34 Component development with COM and CORBA

Client Server component component

IDL Stub

Component “Bus” 69

IDL spec module Reservation {interface Flight_booking { Price ticket_price (in Date day, in Flight number) raises (invalid_date, invalid_number); exception invalid_date {Date when; }; readonly attribute string name; ...} };

35 The role of IDL

• Provide language-neutral interface description of a module’s operations • As a result, enable clients and suppliers written in different implementation languages

The trouble with IDL

• Programmers must write IDL interface in addition to actual software • If from an O-O language, IDL duplicates information present in the code, e.g. C++ header file • Perils of duplication • IDL compiler goes the wrong way! • However: some tools ease the process. 72

36 Pre-.NET approaches: summary

• Object technology is best known basis • Information hiding is key • O-O sufficient by itself: need for autonomous components • Current approaches too heavy: extra work to turn module (e.g. class) into component • IDL is a killer

.NET Framework Design Goals

• Dramatically simplifies development and deployment • Unifies programming models • Provides robust and secure execution environment • Supports multiple programming languages

37 Framework, Languages, And Tools

VB C++ C# JScript J#

Common Language Specification

ASP.NET Visual Studio.NET Windows Web Forms Web Services Forms Mobile Internet Toolkit

ADO.NET and XML

Base Class Library

Common Language Runtime

Operating System 75

Framework, Languages, And Tools

VB C++ C# JScript J#

Common Language Specification

ASP.NET Visual Studio.NET Windows Web Forms Web Services Forms Mobile Internet Toolkit

ADO.NET and XML

Base Class Library

Common Language Runtime

Operating System 76

38 The .NET Evolution

Application

Code and data structures

Before COM, applications were completely separate entities with little or no integration

The .NET Evolution

COM provides a way for components to integrate; However, each component must provide the “plumbing” and objects cannot

directly interact 78

39 The .NET Evolution

With the .NET Framework common language runtime, components are built on a common substrate; No “plumbing” is needed and objects can directly interact 79

Compilation And Execution

Compilation Source Language Code (IL) Assembly Code Compiler Metadata

Native JIT Code Compiler At installation or the first time each Execution method is called

40 Simplify Development

• Completely eliminates COM plumbing •No more… – Registration =>self described apps –GUIDs =>hierarchical namespaces – .IDL files =>unified object model –HRESULTs =>structured exceptions – IUnknown =>common root object – AddRef/Release =>garbage collector – CoCreateInstance =>”new” operator

Simplify Development

• Common Type System – Common instance and type definition • Enables clean OO programming – Classes and interfaces – Constructors, properties, methods, events – Cross language inheritance • Built-in interoperability – With COM – With native (Win32® style) DLLs 82

41 Robust Environment

• Automatic lifetime management – All objects are garbage collected • Exception handling – Error handling first class and mandatory • Type-safety – No buffer overruns, No unsafe casts, Uninitialized variables

Secure Environment

• Security designed-in • Code access security enforcement – Security based on the identity of code – Administratively configurable via policy • ASP.NET integrated authentication of user – Windows identity, Passport®, forms-based, … • Cryptography library with XML DSIG support – Digital signature for XML (www.w3.org/signature)

42 Simplify Deployment And Management

• Zero-impact install – Applications and components can be shared or private • Side-by-side execution – Multiple versions of the same component can co- exist on a system • Assemblies – Contain dependency information

Framework, Languages, And Tools

VB C++ C# JScript J#

Common Language Specification

ASP.NET Visual Studio.NET Windows Web Forms Web Services Forms Mobile Internet Toolkit

ADO.NET and XML

Base Class Library

Common Language Runtime

Operating System 86

43 Unify Programming Models

Consistent API availability regardless of language and programming model .NET Framework

RAD, Subclassing, Stateless, Composition, Power, Code embedded Delegation Expressiveness in HTML pages VB Forms MFC/ATL ASP

Windows API 87

How Much Simpler?

Windows API HWND hwndMain = CreateWindowEx( 0, "MainWClass", "Main Window", WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, (HWND)NULL, (HMENU)NULL, hInstance, NULL); ShowWindow(hwndMain, SW_SHOWDEFAULT); UpdateWindow(hwndMain);

.NET Framework

Dim form As New Form() form.Text = "Main Window" form.Show() 88

44 Factored And Extensible

• The Framework is not a “black box” • Any .NET class is available for you to extend through inheritance – Gives developers much more head room • Plug and Play components and subsystems

The .NET Framework Library

ASP.NET Web Forms Web Services Windows Mobile Internet Toolkit Forms

ADO.NET and XML

Base Class Library

45 The .NET Framework Library

System.Web System.Windows.Forms Services UI Design ComponentModel Description HtmlControls Discovery WebControls Protocols System.Drawing Caching Security Drawing2D Printing Configuration SessionState Imaging Text

System.Data System.Xml OleDb SqlClient XSLT Serialization Common SQLTypes XPath

System Collections IO Security Runtime Configuration Net ServiceProcess InteropServices Diagnostics Reflection Text Remoting Globalization Resources Threading Serialization 91

Base Framework

System Collections Security Configuration ServiceProcess Diagnostics Text Globalization Threading IO Runtime Net InteropServices Reflection Remoting

Resources Serialization 92

46 Data And XML

System.Data OleDb SQLClient Common SQLTypes

System.Xml XSLT Serialization XPath

System.Web Services UI Description HtmlControls Discovery WebControls Protocols Caching Security Configuration SessionState

47 Windows® Forms

System.Windows.Forms Design ComponentModel

System.Drawing Drawing2D Printing Imaging Text

Framework, Languages, And Tools

VB C++ C# JScript J#

Common Language Specification

ASP.NET Visual Studio.NET Windows Web Forms Web Services Forms Mobile Internet Toolkit

ADO.NET and XML

Base Class Library

Common Language Runtime

Operating System 96

48 Languages

• The .NET Platform is language neutral – All .NET languages are first class players – You can leverage your existing skills • Common language specification – Set of features guaranteed to be in all languages • We are providing – Visual Basic®, C++, C#, J#, JScript® • Third-parties are building – APL, COBOL, Delphi, Pascal, Eiffel, Haskell, ML, Oberon, Perl, Python, Scheme, Smalltalk…

Standardization

• A subset of the .NET Framework and C# submitted to ECMA – Adopted as International standards in Dec. 2001 – In the ISO fast-track process now – Co-sponsored with Intel, Hewlett-Packard • Common language infrastructure – Based on common language runtime and base framework – Layered into increasing levels of functionality 98

49 Summary

• The .NET Framework – Dramatically simplifies development and deployment – Unifies programming models – Provides robust and secure execution environment – Supports multiple programming languages

Execution scheme under .NET

C# VB C++ Eiffel .NET languages

Language compilers

IL code (plus metadata) Loader JIT + verifier Unjitted routine call Managed code

Execution 100

50 The basic .NET component unit

Result of compilation is an assembly Assembly is a set of classes Unit of: • Delivery and deployment • Naming (through namespaces) • Security (level for granting permissions) • Versioning & side-by-side execution

Self-documenting through “manifest”

101

The Single Product Principle

• There is one product: SOFTWARE

e.g., Eiffel: use single, seamless notation throughout the development cycle Rely on tools to produce documentation Maintain just one product!

102

51 Single Product Principle in .NET

• It’s all in the metadata!

Definition: • Metadata is information about a module’s external properties, not necessarily needed for executing the module, but retained after compilation along with the binary code

103

Examining an assembly with ildasm

104

52 How is the metadata stored?

• Stuffed into PE (Portable Executable) format • To Windows, result of compiling an assembly looks like ordinary binary (*.dll or *.exe), but contains all kinds of supplementary information • Will execute on .NET only

105

The Portable Executable (PE) format

106

53 Execution model: the role of metadata

C# VB C++ Eiffel .NET languages

Language compilers

IL code (plus metadata) Loader JIT + verifier Unjitted routine call Managed code

Execution 107

Metadata contents

• Manifest: assembly description – Name, version, culture – Security properties: Needed permissions – Public key if present – Dependencies on other assemblies • List of classes • For each class: – Features: methods, fields, properties, events – Signatures (argument and result types) of each – Interfaces it implements • Custom attributes (see next) 108

54 Working with metadata

Letting a program access metadata: • Use System.Reflection Examining metadata interactively: • Use ILDasm Can convert metadata to: • XML • COM type libraries (regasm) To produce metadata: • Use System.Reflection.Emit 109

.NET component model

• Single product principle: full reflectivity; assemblies are self-documenting • (Groups of) classes directly yield components • No extra plumbing •No IDL • Full application of Object-Oriented principles • Multi-language interoperability

110

55 Part V

Designing .Net/COM+ Component-Based Architectures (See: Architecture Driven Development at http://www.wildetechnologies.com/video/WildeVSLaunch2003.ppt, business process modeling at http://www.enterprise-component.com/docs/WebServWs.ppt Web Services Software Development Lifecycle at http://www.enterprise-component.com/docs/WebServWs.ppt, and .Net vs. J2EE in http://www.disi.unige.it/person/ReggioG/ISII01/DotNet.ppt)

111

Component-based software development

• Creating re-usable language-neutral software components that conform to a binary component standard • Removes many of the problems faced in trying to develop re-usable pieces of software • Many standards exist – COM, CORBA, Java Beans, .Net • 2 MS standards – COM (Component Object Model) and .NET

112

56 Problems with traditional development

Lack of binary compatibility • XYZ Corp markets a C++ library containing a class MyClass • MyClass is extremely useful so ABC Software Company creates a dozen of applications that use MyClass • XYZ Corp decides to fix some bugs in MyClass. In doing so, they add another private class member. • The new class is not binary- compatible with old one – ABC Software will have to recompile all its applications

113

Problems with traditional development

Language compatibility • Without COM, software developed in one language cannot be easily used from another • C/C++ and Visual Basic example: • VB can use C-functions but only in a limited manner • VB cannot use C++ classes • C/C++ cannot use functions/procedures/classes developed in VB • Result: headache for library vendors and users alike

114

57 Problems with traditional development

Location dependence • Without COM, the code using a library is locked into having the library at a particular location, e.g. in a DLL sitting in a system directory

115

COM to the rescue

• Complete binary compatibility – new versions of a library can simply replace the old version. It’s not necessary to recompile the code that uses that library • Language independence:

VB / C / C++ / FORTRAN / JavaScript / ….

C++ VB C Fortran

COM components 116

58 Conventional solution

• “Portable” base class library developed in C++ using only ANSI C++ features

• COM wrappers for the classes to make them accessible from other languages

117

User desktop FORTRAN Server-side application in VB program script - JScript

IArray1D IArray2D IWave1D IWave2D

COM wrappers (C++, tied to Windows)

CArray1D CArray2D CWave1D CWave2D

CInternal1 CInternal2

Base library (ANSI C++ only, portable)118

59 Pros and Cons

• Library can be used from • Library has to be developed in a a variety of languages single language – C++/C • Binary compatibility is • Difficult to develop portable maintained across versions code • Portability not complete due to • Base class library is differences in compilers portable to all platforms • Source code has to be supporting C++ distributed • Base library cannot access rich functionality provided by the platform in runs on

119

The .Net solution

What is .Net?

• Execution environment with managed memory • Rich class library - .Net Framework • Common Language Specification / Runtime that allows for seamless interoperability between different programming languages

120

60 How it works

VB Source C# Source C++ Source Fortran File File File Source File

VB.net C# C++ .Net Fortran .Net compiler compiler compiler compiler

Intermediate OS / CPU independent Language

Just-In-Time Compiler

Executable code in memory 121

.Net solution

Rich functionality Web Page provided by the .Net Framework: JScript Application •Essential classes: VB collections, string manipulation, math etc. •Security VB •User interface C# Fortran •Networking Cobol •Graphics C++ •Database access Others •Etc. Base class library

122

61 Pros and Cons

• Seamless interoperability between • Possible portability problems: different languages • A lot less platforms will be • Binary compatibility across all supported CPUs and operating systems • Cost of .Net implementations • Effortless portability to all for non-Windows platforms is platforms supporting .Net unknown • Full interoperability with COM • Time of availability of non- • Rich platform functionality can be Windows implementations is used in the base library unknown • Possibly reduced development time • Exactly which platforms will be and increased robustness due to supported is unknown services provided by .Net e.g. • Considerable performance memory management penalty

123

Towards Web Services (http://msdn.microsoft.com/webservices/building/wse/default.aspx)

Web Services Enhancements (WSE 2.0)

http://msdn.microsoft.com/webservices/building/wse/default.aspx

Add-on to Microsoft Visual Studio .Net and the Microsoft .Net Framework

policy framework, enhanced security model, message-based programming model, and support for multiple hosting environments

Plateaus of adoption

Integration as an afterthought

Web services façades

Managed Web services and, finally

Paradigm shift

Industry currently focuses on the second plateau 124

62 Integration as an Afterthought

The current enterprise conjecture consists of a collection of self- contained custom or packaged applications

Packaged applications may expose functions via an API allowing some level of point-to-point integration

125

Web Services Façades

Adopting Web services first requires "wrapping" existing applications with a Web services façade

The resulting architecture resembles early EAI implementations, but provides the added benefit of standard protocols

126

63 Managed Web Services

In most cases, package applications are not designed to enable the replacement of underlying services

As a result, the resulting Web architecture remains a hybrid in which some applications leverage common infrastructure services while others access their own internal services 127

Paradigm Shift

In a true service-oriented architecture, all business services use a common set of business-neutral services for logging, notification and security

128

64 Challenges

Evolving standards

Immature tools

Semantic mapping

Network reliability

Performance

Application ownership

Learning curves

129

“Agile” Methodologies

See Session 8 Sub-Topic 2 Presentation:

Sample Project Development Methodology

http://www.thoughtworks.com/library/agileEAIMethods.pdf

http://www.thoughtworks.com/library/newMethodology.pdf

130

65 Part VI

Conclusion

131

Summary

JWS provides the convenience of desktop applications for downloaded applications with Zero Client Administration

Microsoft’s DOC platforms implement the OMA architecture

Provide platform specific support for services

Support an integrated set of horizontal and vertical facilities

Capabilities are bundled with the Operating System

COM+ introduces a new naming service technology

DNA provide transactions and messaging services

DNA support web-enabling which is being extended with trading capabilities via Web Services

.Net/COM+ simplifies application development

Server Components v.s. Client Components

Enterprise apps & Web Services v.s. workgroup apps 132

66 Goals

Show by example that .Net/COM+ makes it:

As easy to develop Server Components as it is to develop Client Components

As easy to deliver enterprise applications and Web Services as it is to deliver workgroup apps!

133

Readings

Microsoft .NET Distributed Applications: Building Application Servers

Chapters on .Net Remoting and COM+ Services

Handouts posted on the course web site

Explore .Net/COM+ Environment

Read related white papers/documentation on the .Net/COM+ environments

134

67 Project Frameworks

Project Frameworks Setup (ongoing)

Apache Web Server (version 1.3.28/2.0.47, www.apache.org)

Perl (version 5.8.0, www.perl.com)

Microsoft IIS with COM+/.Net and ASP

Sun One Active Server Pages 4.0 http://wwws.sun.com/software/chilisoft/index.html

Apache Tomcat

Macromedia JRun4

Apache Cocoon 2/XSP

Visibroker, Orbacus

RMI-IIOP

WebLogic 8.1, WebSphere 5.0, JBoss

Inprise AppServer, Sun ONE, Sybase EAServer, Oracle 9i, IONA iPortal, Xoology Concerto, Aligo M-1, Advanced Network Systems WebIx

GOAL Group OpenCCM, ExoLab.org OpenCCM, iCMG K2-CCM (C++), MICO/E (Eiffel ORB), JavaCCM, TAO Group, IONA iPortal (no CCM), Borland AppServer (no CCM), Sourceforge MI-3 (“Mission Impossible 3”) and CIF projects 135 Visual Studio .Net 2003 / .Net Framework SDK

Assignment

Explore the references to .Net/DNA Application Server technology

Homework #6 due date is 11/12/03

Homework #7: due date is 11/26/01

136

68 Next Session: XML-Based Capabilities in Component-Based Environments

.Net Environment (continued)

EAI Environments

B2Bi Environments

BPM Environments

Channel Independence and Pervasive Devices

137