Java and z/OS (and RDz)

®

IBM Software Group

© 2016

IBM Corporation

Java and z/OS (and RDz)

Jon Sayles – [email protected]

mailto:[email protected]

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

http://www.s390java.com/index.htm


3

TrademarksTrademarks

The following are trademarks of the International Business Machines Corporation in the United States and/or other countries. For a complete list of IBM Trademarks, see www.ibm.com/legal/copytrade.shtml: AS/400, DBE, e-business logo, ESCO, eServer, FICON, IBM, IBM Logo, iSeries, MVS, OS/390, pSeries, RS/6000, S/30, VM/ESA, VSE/ESA, Websphere, xSeries, z/OS, zSeries, z/VM

The following are trademarks or registered trademarks of other companies

Lotus, Notes, and Domino are trademarks or registered trademarks of Lotus Development CorporationJava and all Java-related trademarks and logos are trademarks of Sun Microsystems, Inc., in the United States and other countriesLINUX is a registered trademark of Linux TorvaldsUNIX is a registered trademark of The Open Group in the United States and other countries.Microsoft, Windows and Windows NT are registered trademarks of Microsoft Corporation.SET and Secure Electronic Transaction are trademarks owned by SET Secure Electronic Transaction LLC.Intel is a registered trademark of Intel Corporation* All other products may be trademarks or registered trademarks of their respective companies.

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.

IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply.

All customer examples cited or described in this presentation are presented as illustrations of the manner in which some customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics will vary depending on individual customer configurations and conditions.

This publication was produced in the United States. IBM may not offer the products, services or features discussed in this document in other countries, and the information may be subject to change without notice. Consult your local IBM business contact for information on the product or services available in your area.

All statements regarding IBM's future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only.

Information about non-IBM products is obtained from the manufacturers of those products or their published announcements. IBM has not tested those products and cannot confirm the performance, compatibility, or any other claims related to non-IBM products. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products.

Prices subject to change without notice. Contact your IBM representative or Business Partner for the most current pricing in your geography.

References in this document to IBM products or services do not imply that IBM intends to make them available in every country.

Any proposed use of claims in this presentation outside of the United States must be reviewed by local IBM country counsel prior to such use.

The information could include technical inaccuracies or typographical errors. Changes are periodically made to the information herein; these changes will be incorporated in new editions of the publication. IBM may make improvements and/or changes in the product(s) and/or the program(s) described in this publication at any time without notice.

Any references in this information to non-IBM Web sites are provided for convenience only and do not in any manner serve as an endorsement of those Web sites. The materials at those Web sites are not part of the materials for this IBM product and use of those Web sites is at your own risk.


Java and the software world


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


Java == “Write once…run anywhere”

The key is the “isolation of program from hardware …”


Java Bytecode – Isolating programs from hardware


Java Programs Bytecode the Java Virtual Machine

Java Virtual Machine1. You code in a file

named: Xxxxx.java

2. You compile to a Java

class: Xxxxx.class

3. You run your program

on any supported java

platform - using a Java

Virtual Machine (a JVM)

1.

2.

3.


Java Tools … RDz – as a Java SDK


Java and procedural programming constructs


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


Java COBOL – Programming similarities (1 of 2)


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.


How to write and test Java using RDz


Java development and RDz Perspectives

COBOL tools are in the z/OS Projects Perspective


Java development and RDz Perspectives

Java tools are in the Java Perspective


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


Open the Java Perspective

This is the Java Perspective … (different Views will display)


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


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


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.


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


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


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…


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 <your TSO ID>

Name the Archive file

Click OK

Click Finish - Note that you need R/W authority in UNIX


Drag & Drop onto the UNIX File System

Just like with MVS files, you may drag & drop (or copy &

paste) files and folders from your PC up to UNIX on z/OS

Note that you need R/W authority to Copy/Paste files into

the z/OS UNIX File System


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 <your TSO ID>

Right-click over your TSO ID and select Search…

Search for: hello


Search Results

You should be able to open a Java file

But not a jar file


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

http://www.ibm.com/servers/resources/sdkguide.zos.pdf

http://www.ibm.com/servers/eserver/zseries/software/java/

http://www.ibm.com/software/awdtools/rdz/

http://www.ibm.com/software/rational/cafe/community/cobol/rdz?view=overview

http://www.ibm.com/developerworks/websphere/library/techarticles/0703_england/0703_england.html

http://www.ibm.com/developerworks/rational/library/10/portingjavaapplicationstozos/index.html


30

§ 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

CICS TS

Client

3270or

HTML Presentation

Integration

logic

Data

access

Transaction

DIP

Business

logic

B

CICS Application ArchitectureJava can go here!


31

M

P

P

B

M

P

I

F

P

CEETDLI Interface

JNI

Base

App

DB

JDBC / SQL

IMS Java

App

DLI

Database

View

CEETDLI Interface

JNI

Base

App

DB

JDBC / SQL

IMS Java

App

DLI

Database

View

JMP JBP

CEETDLI Interface

JNI

Base

App

DB

JDBC / SQL

IMS Java

App

DLI

Database

View

CEETDLI Interface

JNI

Base

App

DB

JDBC / SQL

IMS Java

App

DLI

Database

ViewStored

Procedure EJBJCICS

IMS DB

DRA

ODBA

CEETDLI Interface

JNI

Base

App

DB

JDBC / SQL

IMS Java

App

DLI

Database

View

Java Virtual MachineJava Virtual Machine

Java Virtual Machine

Java Virtual Machine

Java and IMS – Environments

CICSDB2 WebSphere

IMS


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

http://www.ibm.com/developerworks/systems/library/es-java-batchz.html


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?


AMS Method/ExampleA 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)");

Documents

Java and z/OS (and RDz)