®
IBM Software Group
Java and z/OS (and RDz)
Jon Sayles – jsayles@us.ibm.com
© 2016 IBM Corporation IBM Software Group | Rational software Merrill Class
. They’ll have RDz exposure . Terms & Concepts & Vocabulary Remove fear of Java Analogies – Procedural vocabulary 20 – 30 students - mix of young + old (mostly old) dudes . Call COBOL from Java Java doesn’t create an .exe Objects . z/OS Java Standard z/OS environment JCL – pointing to Unix Aware of JVM – can call COBOL http://www.s390java.com/index.htm IBM Software Group | Rational software Trademarks Trademarks
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NOTES:
Performance is in Internal Throughput Rate (ITR) ratio based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here.
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3 IBM Software Group | Rational software
Java and the software world IBM Software Group | Rational software Why Learn Java? . Common code across platforms Java code can be reused in CICS, WAS, Batch, and other application program platforms . Modern, powerful, easily available developers/tools Allow to extend usage of the mainframe while using a more modern programming language and tooling Most of today’s investment by the world’s primary software vendors involves Java . Even things like ODM, Business Rules, etc. wrap around Java . Large code base of pre-built applications, tools, frameworks and design patterns . Legacy of agile development processes (JUnit, etc.) replacing Waterfall lif . You’re not retiring next week . Cost, cost, cost: Java can be run more cheaply than COBOL or other traditional mainframe languages when using a zAAP processor IBM Software Group | Rational software Java == “Write once…run anywhere”
The key is the “isolation of program from hardware …” IBM Software Group | Rational software Java Bytecode – Isolating programs from hardware IBM Software Group | Rational software Java Programs Bytecode the Java Virtual Machine
1. 2.
1. You code in a file named: Xxxxx.java Java Virtual Machine
2. You compile to a Java class: Xxxxx.class
3. You run your program on any supported java platform - using a Java 3. Virtual Machine (a JVM) IBM Software Group | Rational software Java Tools … RDz – as a Java SDK IBM Software Group | Rational software
Java and procedural programming constructs IBM Software Group | Rational software Java COBOL – Development similarities
. Java source file COBOL source file . Java class file COBOL module . Java bytecode COBOL “object module” (COBOL Compiler output) . Java virtual machine the z/OS operating system . There are many many, many additional parallels between Java and COBOL – especially at the language level IBM Software Group | Rational software Java COBOL – Programming similarities (1 of 2) IBM Software Group | Rational software Java COBOL – Programming similarities (2 of 2)
• Package Library • Class Module • Method Subroutine • Variables Variables • Statements Statements: Math, I/O (QSAM/VSAM), Conditionals, Branching, Database (DB2, IMS, etc.), CICS, IMS TM, Display, U.I. – etc. IBM Software Group | Rational software
How to write and test Java using RDz IBM Software Group | Rational software Java development and RDz Perspectives . COBOL tools are in the z/OS Projects Perspective IBM Software Group | Rational software Java development and RDz Perspectives . Java tools are in the Java Perspective IBM Software Group | Rational software Java development using RDz . Open the Java Perspective: Package Explorer view . Create a Java Project . Create a Package . Create a HelloWorld Class . Run as a Java Application . Set Break points . Step through code to branch to the method . Debug as Java application . Port the Package to z/OS (UNIX File System) . Drag & Drop a file to UNIX . Search in USS IBM Software Group | Rational software Open the Java Perspective
This is the Java Perspective … (different Views will display) IBM Software Group | Rational software Create a Project, Package and Class
. Right-click inside of the Package Explorer View and select: New > Java Project Name the Project HelloWorldProject and click Finish . Right-click over the HelloWorld Project and select: New > Package Name the Package: helloWorldPackage and click Finish (note - lower case “h”) . Right-click over the helloWorldPackage and select: New > Class Name the Class: HelloWorld Click Finish
Your new java Class file IBM Software Group | Rational software Your first example Java Class (code)
. From the slide notes, copy and paste the following code into the HelloWorld Class . Press Ctrl/S to save your work Note that if you get any syntax errors, check the package name or redo this paste step
The code is embedded in this slide’s Notes area IBM Software Group | Rational software Run as a Java Application . From the Package Explorer; expand your project > package > class . Select HelloWorld.java and Run it As a Java Application Note the System.out.println results in the Console view. IBM Software Group | Rational software Debug as a Java Application . Double-click your mouse over the left-hand frame of your source file, to create 3 breakpoints on the System.out.println statements (as shown in the screen capture) . From the Package Explorer; expand your project > package > class . Select HelloWorld.java and Debug it As a Java Application Note; You will be prompted to switch to the Debug Perspective … do so
IBM Software Group | Rational software Debugging Java . From the Debug toolbar Use Step into - to run a statement, and step into a called method Use Step return - to run the remaining code in a called method, returning to the Next Sequential instruction Use Step over - to run a statement - and run through all of the code in a called method Use Resume - to run to the next breakpoint, or to normal EOJ Use Terminate - to halt your debug session
You can alter variable values on the fly IBM Software Group | Rational software Export to Remote JAR file - 1 of 2 . Return to the Java Perspective . Right-click over your helloWorldPackage, select Export . Type rem in the filter, select Remote JAR file and press Next >
. Check the box for your Project
. Click Browse… IBM Software Group | Rational software Export to Remote JAR file - 2 of 2 . Expand your named Connection to z/OS . Scroll down inside of the Unix System Services directories until you see: u
. Note that you need R/W authority to Copy/Paste files into the z/OS UNIX File System IBM Software Group | Rational software Search in z/OS UNIX for your exported Java source . Return to the z/OS Projects Perspective . From Remote Systems . Expand z/OS UNIX Files . Scroll down inside the directories until you see: u
. You should be able to open a Java file But not a jar file IBM Software Group | Rational software Links
. Java - http://www.ibm.com/servers/resources/sdkguide.zos.pdf . JzOS - http://www.ibm.com/servers/eserver/zseries/software/java/ . RDz - http://www.ibm.com/software/awdtools/rdz/ . RDz Hub - http://www.ibm.com/software/rational/cafe/community/cobol/rdz?view=overview . Writing Java applications for z/OS – White Paper http://www.ibm.com/developerworks/websphere/library/techarticles/0703_england/ 0703_england.html . Porting Java applications to z/OS – White Paper http://www.ibm.com/developerworks/rational/library/10/portingjavaapplicationstozo s/index.html IBM Software Group | Rational software CICS Application Architecture Java can go here!
CICS TS Transaction
3270 or Integration Business Data Client HTML logic logic access Presentation P I B D
§ Best practice in CICS application design is to separate key elements of the application, in particular: Presentation logic eg. - 3270, HTML, XML Integration or aggregation logic - Menu, router, tooling Business logic - Reusable component Data access logic - VSAM, DB2, IMS, … § Provides a framework for reuse and facilitates separation of concerns, clear interfaces, ownership, and optimization § Allows callable business logic – parameters passed via COMMAREA § Can use Java for any of the programs above, but JCICS does not support BMS
30 IBM Software Group | Rational software Java and IMS – Environments DB2 CICS WebSphere
DLI IMS Java Database App View DLI IMS Java Database App View
JDBC / SQL A p p DLI Stored IMS Java Database JDBC / SQL App DB A View p p
Base DB
JDBC / SQL JNI A Base p p CEETDLI Interface JCICS DB Procedure EJB JNI Base CEETDLI Interface
JNI
CEETDLI Interface Java Virtual Machine Java Virtual Machine Java Virtual Machine IMS
DLI DLI IMS Java IMS Java Database Database App App View View
JDBC / SQL JDBC / SQL A A p p p p
DB DB
M B I Base Base JNI JNI ODBA P M F CEETDLI Interface CEETDLI Interface P P P JMP JBP DRA Java Virtual Machine IMS DB
31 IBM Software Group | Rational software Java Batch
Note: There are 5 or 6 alternative architectures for running Java Batch
http://www.ibm.com/developerworks/systems/library/es-java-batchz.html IBM Software Group | Rational software Additional program
From the slide Notes, select and copy all of the Java code . From RDz: Create a new Class in your helloWorldPackage Name the Class HelloWorld2 Read through the code, and save your Java file. . Run . Set breakpoints . Debug
. What does this program do? . How does it do what it does? What are the programming patterns? Have you ever done anything like this in COBOL? IBM Software Group | Rational software AMS Method/Example
A class that provides a Java interface to z/OS Access Method Services (IDCAMS). Output from IDCAMS (DD SYSPRINT) is redirected by default to a String (getOutputLines()). The method setOutputDDName(String) may be used before execute() to direct IDCAMS output to a pre-allocated DDNAME.
Example: LISTC output directed to outputLines String buffer.
AccessMethodServices ams = new AccessMethodServices(); ams.addInputLine("LISTC LEVEL(ACCTING)"); int rc = ams.execute(); System.out.println("IDCAMS output:"); System.out.println(ams.getOutputLines());
Example: LISTC output directed to temporary dataset
String ddname = ZFile.allocDummyDDName(); ZFile.bpxwdyn("alloc fi(" + ddname + ") da(&&IDTEMP) new delete reuse msg(2)"); AccessMethodServices ams = new AccessMethodServices(); ams.setOutputDDName(ddname); ams.addInputLine("LISTC LEVEL(BILLING)"); int rc = ams.execute(); ... ZFile.bpxwdyn("free fi(" + ddname + ") msg(2)");