The Caffeinated Mainframer

Kenny Smith

Principal Consultant

Strongback Consulting

kenny.smith@strongback.us

twitter: @smithkenny

Matthew Hardin

Senior Consultant

mhardin@strongback.us

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About Us: Strongback Consulting

IBM Advanced Business Partner

– Rational, WebSphere, Lotus, Information Management SVP certified

– Strongly focused on Enterprise Modernization and application lifecycle management

– Key Industries Served: Finance, Insurance, Healthcare, Manufacturing, Government

– Rational Design Partner for HATS and other Rational enterprise modernization technologies

Discover us at:

http://www.strongback.us

Subscribe to us at

http://blog.strongbackconsulting.com

Socialize with us on Facebook & LinkedIn

http://www.facebook.com/StrongbackConsulting

http://www.linkedin.com/company/290754

Why Java on System z?

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Abundance of Java and Java skills

zAAP Processors - cost effective workload

mgmt

Combining of traditional batch with modern

frameworks

Access to MVS using the JZOS API

Abundance of Java

#2 Programming language – Tiobe– February 2013

–C ranks #1 (frequently trades places with Java)

–COBOL ranks #24

–Assembler ranks #19

Ubiquity of architectural frameworks

–Unit testing, relational object mapping, security, dependency injection, etc.

Language learning resources are abundant

–Free tutorials available on http://www.ibm.com/developerworks

–More free tutorials at Sun’s… err … <cough> Oracle’s </cough> website

–Required course of most computer science programs

4 *http://www.langpop.com/

zAAP Processors – Cost Effective Solution

A specialty z processor engine

Provides an attractively priced execution environment for web-based

applications and SOA-based technologies, such as XML and Java

Simplifies and reduces server infrastructures

Maximizes the value of your mainframe investments

– increased system productivity by reducing the demands and capacity

requirements on general purpose processors which may then be available for

reallocation to other mainframe workloads.

Lowers the overall cost of computing for WebSphere Application Server

and other Java technology-based applications

–hardware, software and maintenance savings.

JIT on the z has greatly increased performance on the z.

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WebSphere App Server for z/OS

Exploit the benefits of z/OS

WLM

–configure down to the request level, not just app level with special tags

SAF (RACF) - provides security definition and security

enforcement for the product

RRS—used for global syncpoint coordination between WAS z/OS

and other participants in two-phase commit global transactions

Cross memory communications

–JDBC type 2 uses this for comms to DB2

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Java Batch Processing in OLTP Runtime

Running Java batch in the same execution runtime as Java OLTP

– provides an opportunity to mix and manage the two processing types together under the same

management model.

WebSphere Application Server allows the WAS platform to mix and manage the two

workload types.

WebSphere Compute Grid now included in WebSphere App Server 8.5

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Web Container EJB Container Batch Container

WebSphere Application Server

WebSphere Modern Batch

Container managed execution of batch jobs: Provides the structure and support function

that Java batch applications require, and helps you avoid the “custom middleware trap.”

Job control interface: An XML file that describes the Java class files that are used in a

batch step and the steps that are included in the batch job.

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Job checkpoint and restart

capability: Ability to create

checkpoints on the basis of record

count or time. This enables

restarting a job from a known

checkpoint.

Common batch data stream

(BDS): Contains functions that

abstract data into easily accessible

record formats so that the batch

programming can focus on the

business functions rather than

basic code that reads and writes

the data.

WebSphere Application v8.5 Infrastructure What’s New…

IBM Workload Deployer

IBM JVM

WebSphere Application Server Foundation

WebSphere eXtreme Scale

Rational Application Developer

Tools

Runtime

WAS Dev Tools for Eclipse

DataPower XC10

WebSphere Compute Grid

WebSphere Virtual

Enterprise

Intelligent Management

Pack

Pattern for Web

Applications WAS HV

Eclipse

Fit for Purpose

Application Foundation

Cloud & Operational Management & Efficiency

IBM Worklight

Studio

WebSphere Application Server V8.5

( WVE and WCG Included with WAS ND and WAS for zOS

& Liberty profile with all editions)

WAS HV V8.5

(Intelligent Management)

Mobile Apps (Web, Hybrid,

Native)

IBM Worklight Server

Eclipse

IBM PureApplication System

Intelligent Routing

Health Management

Application Edition

Management

Dynamic Clustering

Batch processing

WebSphere Batch

WebSphere Virtual Enterprise

Refresher on V8.5 – Intelligent Management

Enables interruption free application rollout

Monitors the status of your applications with the ability to sense and respond to problem areas

Dynamically provision and start/stop new instances of app server based on workload demands

Ensures priority is given to business critical applications via administrator defined rules

Support that leverages your existing Java online transaction processing (OLTP) infrastructure to support new Java batch workloads

Batch

Modules

Better TCO through management efficiency and performance, Intelligent Management

delivers the ability to sense and respond quickly to changes

Java Frameworks

Don't reinvent the wheel, just

realign it. Anthony J. D'Angelo, The

College Blue Book

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JNI = Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a

Java Virtual Machine to call, and to be called by, native applications and libraries written in

other languages such as C, C++ and assembly.

Get a little close to the metal with JNI

Extend functionality of JZOS, or write functions to cover custom software

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JZOS Java API for developers

A framework acquired by IBM

Now part of the IBM JVM

Preferred method for MVS file access, data type conversion,

MVS Console, etc

Includes a batch launcher

Uses JNI / C to access MVS datasets, VSAM files, QSAM

files, etc.

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Calling Java in batch

BPXBATCH

–The “original” batch java caller.

–Best to run non-Java shell commands on Unix System Services

–The STDOUT and STDERR DD names are not allocated as MVS data

sets

JZOS

–The modern batch caller

–Uses a specific JVM load module

JZOS Batch

Jobs are zAAP eligible

IDE Integration with RDz, RAD

Can run Java based servers as started tasks

Full integration into the Job Entry System

Jobs run in the same address space

Support for DD statements

Move stdin, stdout, and stderr to an MVS Dataset

Gives a valid return code (other than just 1)

Unix System Services

JZOS API

MVS

Calling JZOS Batch

JVMLDMxx

JZOS PROC

JZOS JCL

Java Runtime

Java class

PDS

JES

MC

Programmer

writes and

submits the

JCL

JZOS JCL Skeleton

Job Card

Location of the

JVM Proc

Execute the

generic proc with

vars

Location of the

output

Java shell

environment setup

Java Generic PROC

A parameterized procedure makes it easier to standardize the

environment

A sample is included in the JDK for z/OS

Found under /usr/lpp/java/J7.0_64/mvstools/samples/jcl

–Good for most usage, customize for a given specific instance

Class API Overview:

Access MVS Datasets

–com.ibm.jzos.Zfile – thin wrapper for JNI calls to C I/O library

–com.ibm.jzos.FileFactory - platform-portable file access

Access HFS/zFS files

– java.io, java.nio – standard Java API

–com.ibm.jzos.FileFactory

Access the MVS Console

–com.ibm.jzos.MvsConsole – interface to MVS console and job log

Various z/OS native functions

–com.ibm.jzos.ZUtil

ZFile

com.ibm.jzos.Zfile

Thin JNI wrapper for "C" library I/O routines

Constructor: file name and a mode

–zFile = new ZFile(clusterName, "ab+,type=record");

–ZFile dd = new ZFile("//DD:MYDD", "r");

–ZFile dsn = new ZFile("//'SYS1.HELP(ACCOUNT)'", "rt,type=record");

File name can be a PDS, a PDS member, a DD name, or a VSAM cluster

Accessing VSAM Data

Use Zfile for KSDS, LSDS type VSAM files

String filename = "//DD:KSDS";

String options = "ab+,type=record";

int lrecl = 80;

int keyLen = 8;

ZFile zfile = new ZFile(filename, options)

Methods:

– write(), locate(), read(), update

Zfile: Transaction mode

Open a transaction record dataset:

–ZFile dsn = new ZFile("//SEQ", “rb,type=record,noseek");

–Opens a transaction record for read in binary mode

–“noseek” provides optimal performance for sequential access

FileFactory

• Platform-portable BufferedReader, BufferedWriter, InputStream, or

OutputStream on a text file or a MVS dataset.

rdr = FileFactory.newBufferedReader(“//ZNDVR.PROCLIB”);

wtr = FileFactory.newBufferedWriter(“/home/proclib.txt”);

• Examples:

–/etc/profile

–//DD:INPUT

–//'SYS1.MACLIB(ABEND)'

–//MY.DATASET

Accessing ZFS/HFS Data

Use java.io packages

–Just like accessing distributed data

java.nio

– Improved performance in the areas of buffer management, scalable network and

file I/O, character-set support, and regular-expression matching

Use FileFactory if you need portability

–Test locally on Windows , run in dev/prod against PDS/VSAM data

Data Type Conversion

ByteUtil

–Use to convert bytes from packed decimal to Java long, integer, etc

AssemblerDataTypeFactory, CobolDataTypeFactory

–Works as a Factory pattern to create convenience class objects

Convenience classes for conversion to/from Packed Decimals:

–PackedDecimalAsBigDecimalField

–PackedDecimalAsBigIntegerField

–PackedDecimalAsIntField

–PackedDecimalAsLongField

Creating Data Object from Copybooks

JZOS Record Generator Class

–Found in /<cics_installation_directory>/cics/jzos_recgen.jar

–com.ibm.jzos.recordgen.cobol.RecordClassGenerator

Creates convenience classes that represent data in Copybooks

Uses com.ibm.jzos.fields package to get/set data

Much faster than hand coding

less error prone

Run from JCL Batch, or USS command line

Example Conversion

COBOL Copybook Java Class

MvsConsole Operations

MvsConsole.wto = write to operator

– Writes to the system log file in z/OS

MvsConsole.registerMvsCommandCallback Register call back commands

– Allows running batch jobs to receive commands from the system operator

– start (S) , stop (P) , modify (F)

Access Method Services (IDCAMS)

IDCAMS is primarily used to manage VSAM Files

– Can also access catalog facilities

Typically used via JCL files, but can be called using Java (via JZOS)

Getting the JZOS Jar

Included in the IBM Java SDK for z/OS

Download the JAR file from /usr/lpp/java/J6.0/lib/ext/ibmjzos.jar

– FTP

– …or RDz to drag/drop to your project

Put in lib folder of your project

Or create a user library

Must be in classpath at least

Setup the project for usage

User library makes it easy to reuse the JAR file for multiple projects

During export, the jar is copied with the project artifacts

Must have this jar for syntax check and code assist of JZOS objects!

Rational Developer for the Enterprise Tooling

32

Rational Developer for the Enterprise 9.0

Rational Developer for the Enterprise

Rational

Application

Developer for

WebSphere

Software 9.0

Rational

Application

Developer

Rational

Developer for

System z 9.0

Rational

Developer for

System z

Rational

Developer for

AIX and Linux

9.0

C/C++ Edition

AIX COBOL

Edition

Rational Developer

for i 9.0

RPG and COBOL Tools

RPG and COBOL +

Modernization Tools, Java

Edition

RPG and COBOL +

Modernization Tools, EGL

Edition

Rational Business Developer

Rational

Business

Developer 9.0

Rational Business

Developer

RDz Enterprise Tools: Software Analysis

Allows you to run a static analysis of the resources with which you are working to detect

violations of rules and rule categories.

Detects violations of specific programming rules and rule categories and generates a report

in the Software Analyzer Results view

Code can be viewed in a single interface to analyze each component in a multi-language

application…. Java, Cobol and others.

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RDz Enterprise Tools: Unit Testing

JUnit: A unit test framework for Java

Built into RAD / Eclipse

Tests either pass or fail

Testing in isolation: using Mockito

Mockito is a Java based mocking framework

Only stub what you need, no need to stub everything

Clean and simple syntax

All required documentation can be found in the Javadoc

– EXCELLENT documentation!

– A great example of how to do Java doc right!

Can also create partial mocks

RDz Enterprise Tools: Refactoring

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Refactoring: make system-wide code changes without

affecting the behavior of the program.

Refactoring commands are available from the context

menus of several Java views (e.g. Package Explorer,

Outline) and editors. Many "apparently simple"

commands, such as Move and Rename, are actually

refactoring operations, since moving and renaming Java

elements often require changes in dependent files.

• Extract a class, method, constant or local variable

• Rename a method, variable or class

• Change a method signature

• Many, many other refactoring actions

Operations can be previewed for all of the changes

resulting from a refactoring action before you choose to

carry them out.

Can be performed by scripts.

Code Coverage

Determines what is tested

Answers the question “Have

I tested enough?”

Enforces governance

among the developers for

unit testing

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Code Coverage

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You can customize acceptable coverage levels:

• Type coverage: The percentage of Java types that are

covered in a class

• Method coverage: The percentage of methods that are

covered in a class

• Line coverage: The percentage of lines of code that are

covered in the class file

• Block coverage: The percentage of blocks that are

covered in a class file. A block refers to an executable

unit.

Custom filters control what classes get instrumented in

your project (i.e. filter out POJO classes, etc)

Code Coverage statistics available in multiple views

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• Java-based, platform-independent, open source build tool

• Similar to the make tool used in C programming.

• Platform independent,

• Build your projects on any Java platform

• Trivia: ANT is an acronym for “Another Neat Tool”

42

RDz Enterprise Tools: Automation: Using Ant

ANT View

Similar to Outline view

Open build files and double click

targets to run

Different tool bar options

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Gotchas

JZOS calls run through the ISPF gateway

–Multi-dialog type commands cannot be used (i.e. calling REXX functions)

–Keep in mind security and custom user security exits

Don’t try to substitute all your code with Java

–Some apps are better as COBOL, HLASM, or LE

Use the correct JZOS jar for what you expect to run in PROD

– the API has changed slightly from release to release

–Don’t run Java 7 JZOS jar on a Java 6 JVM

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Best Practices

Make use of the RAD Java tooling

– Refactoring

– Unit Testing

– ANT for build automation, compilation, unit testing, packaging, and deployment

Let JZOS API do the data type conversions

– Understand the Java BigDecimal class and how it relates to currency

Unit testing:

– Use Mockito to mock non-JZOS calls

– Use PowerMock to mock static JZOS calls (Mockito cannot do this, but it otherwise easier to use)

Modify the Java PROC to suit your environment

– You don’t have to use the one provided

– You can create different procs for different situations

Use Team Concert for SCM of the entire application

– Batch JCL scripts, Java classes, web projects

– RTC can do build, promotion & deployment on ALL the artifacts at once 46

Key points to take away

There are many programming options for Java on z/OS

Java is cost-competitive with COBOL, HLASM, and PL/I

loads

Java batch allows you to mix and match batch and OLTP

workloads

Batch loads can be reworked and be more flexible for

your business needs

The JZOS API gives the developer a full range of access

to many MVS subsystems

Rational Developer for the Enterprise is a complete

package for Java development on system z

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Resources

Check out all our links for our presentations, including this one

–https://delicious.com/strongback/tag_bundle/Innovate2013

–“one link to rule them all”

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About Us: Strongback Consulting

IBM Advanced Business Partner

– Rational, WebSphere, Lotus, Information Management SVP certified

– Strongly focused on Enterprise Modernization and application lifecycle management

– Key Industries Served: Finance, Insurance, Healthcare, Manufacturing, Government

– Rational Design Partner for HATS and other Rational enterprise modernization technologies

Discover us at:

http://www.strongback.us

Subscribe to us at

http://blog.strongbackconsulting.com

Socialize with us on Facebook & LinkedIn

http://www.facebook.com/StrongbackConsulting

http://www.linkedin.com/company/290754