WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

752 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

21.1 Overview of WebSphere Batch

Batch applications are designed to execute long and complex transaction processing that

typically executes computationally intensive work. This type of processing requires more

resources than traditional online transactional processing (OLTP) systems. Batch applications

run as background jobs described by a job control language and use a processing model

based on submit, work, and result actions. The execution of batch processes can take hours

and the tasks are typically transactional, involving multi-step processes.

WebSphere Application Server V8.5 with WebSphere Batch supplies a unified batch

architecture. Using XML job control language (xJCL), WebSphere Batch provides consistent

programming and operational models. WebSphere Batch makes use of a batch technology

that is optimized for Java and supports long-running applications. Ensuring agility, scalability,

and cost efficiency for enterprises.

21.1.1 Batch jobs

A batch job consists of a series of definitions that direct the execution of one or more batch

applications and specifies their input and output. A batch job performs a specific set of tasks

in a predefined sequence to accomplish specific business functionalities.

Batch job workloads are executed in a batch container in WebSphere Application Server

environments. This batch container is the main engine responsible for the execution of batch

applications. It runs batch jobs under the control of an asynchronous bean, which can be

thought of as a container-managed thread. The batch container ultimately processes job

definitions and carries out the lifecycle of jobs.

WebSphere runs batch applications that are written in Java and implements a WebSphere

batch programming model. They are packed as EAR files and are deployed to the batch

container hosted in an application server or cluster. Batch applications are executed

non-interactively in the background.

Batch applications implement one of two programming models:

 Transactional batch

These applications handle large amounts of work based on repetitive tasks, such as

processing a large number of records.

 Compute-intensive applications

Compute-intensive applications perform work that requires large amounts of system

resources, in particular CPU and memory. The application is responsible for providing all

of the logic for performing the necessary work.

Batch jobs can perform a series of tasks that are a combination of transactional and

compute-intensive tasks to complete the execution of a batch application.

21.1.2 Batch applications

Batch applications are programs designed to execute non-interactive tasks in the

background. Input and output is generally accessed as logical constructs by the batch

application and are mapped to concrete data resources by the batch job definition.

Chapter 21. WebSphere Batch 753

Batch applications are Java EE applications consisting of Plain Old Java Objects (POJOs).

These applications conform to a few well-defined interfaces that allow the batch runtime to

manage the start of batch jobs designed for the application.

Batch work is expressed as jobs, which are made up of steps that are processed sequentially.

All jobs contain the following information:

 The identity of the batch application that performs the work

 One or more job steps that must be performed to complete work

 The identity of an artifact within the application that provides the logic for each job step

 Key and value pairs for each job step that provide additional context to the application

artifacts

Jobs for batch applications contain additional information specific to the batch programming

mode:

 Definitions of sources and destinations of data

 Definitions of checkpoint algorithms

21.1.3 Elements of the batch environment

A typical batch environment consists of a job scheduler, batch container, batch applications,

jobs, interfaces for management functions, and database tables, as shown in Figure 21-1.

Figure 21-1 The batch elements

The following list describes the elements of a batch environment:

 Job scheduler

The job scheduler is the batch component that is hosted in an application server or in an

application server cluster. It provides all job management functions, such as submit,

cancel, and restart. It also maintains a history of all jobs, including those waiting to run,

those running, and those having already run. It accepts and schedules the execution of

batch jobs, manages the job database, assigns job IDs, and selects jobs to run.

WebSphere

Application Server

WebSphere

Application Server

Batch

container

Java EE

Batch

application

JDBC

Scheduler tables

Container tables

Batch

applications

Classes

and APIs

xJCL

Job

scheduler

JDBC