java batch

Java Batch(JSR-352)

M.Eray Koçak | Software Infrastructure

1950’s-60’s Batch Processing Era

The era came to an end, but need for batch processing continues to exist.

Evolution of Processing

Common Requirements

Common Requirements Logging Checkpointing Parallelization Transaction Management Operational Control

• Start• Stop• Restart

JSR-352

https://jcp.org/aboutJava/communityprocess/final/jsr352/index.html

Led by IBM The proposal intended to specify

• Batch job• Batch job step• Batch application• Batch executor• Batch job manager (Considered in a future revision of the

specification)• Final Release on 24 May, 2013




JSR-352[Final Release]

Describes Job Specification Language Java Programming Model Runtime environment of Batch Applications

Targets both Java SE and Java EE platforms. Requires Java 6 or higher. Works with dependency Injection(DI)

containers

Domain Language of Batch

Job Specification Language

Job Job Level Listeners Job Level Properties

Step

Each step may be either a chunk type step or batchlet type step

Chunk Periodically Checkpointed ItemBased

Batchlet Task-oriented

Chunk

Must have only one ItemReader and ItemWriter ItemProcessor is optional but only a single

processor element may be specified. Each Chunk is processed in a separate transaction ItemWriter is called once per chunk BatchRuntime writes checkpointinfo to

JobRepository

Chunk Exception Handling

Batchlet

Task-Oriented Batch Step Mutually exclusive with the chunk element. Closer analogy to CBBatchBase.prepare/finish

Step Listeners

Chunk Step Step Listener Item Read Listener Item Process Listener Item Write Listener Chunk Listener Skip Listener Retry Listener

Batclet Step Step Listener

Step Sequence

Transition Elements

Transition Elements next - directs execution flow to the next execution

element. fail - causes a job to end with FAILED batch status. end - causes a job to end with COMPLETED batch

status. stop - causes a job to end with STOPPED batch

status.

Transition Elements

Syntax

Step Partitioning

Step Partitioning

PartitionMapper partitionsOverride -> behaviour when Restart

PartitionReducer PartitionCollector PartitionAnalyzer

Batch and Exit Status

Batch Status : Runtime Status Value STARTING STARTED STOPPING STOPPED FAILED COMPLETED ABANDONED

Exit Status: User-defined Any String

Job XML Substituion

Job XML supports attribute value substitution Substitutions expressions may include a default

value using the "?:" operator Value is substituted with • Any resolvable Job Properties• Job Parameters• Partition Plan• System Properties

Job XML Substitution

Batch Programming Model

Described by interfaces, abstract classes, and field annotations.

Javax.batch package and subpackages

Batch Property

Must be used with the standard @Inject annotation (javax.inject.Inject).

Used to assign batch artifact property values from Job XML to the batch artifact itself

Batch Contexts

StepContext and JobContext are accessible via @Injection

Batch Runtime must ensure the correct context object is injected according to the job or step currently executing.

Job Metrics

Chunk-type step metrics are avaliable through the StepExecution runtime object. READ_COUNT, WRITE_COUNT, COMMIT_COUNT, ROLLBACK_COUNT, READ_SKIP_COUNT, PROCESS_SKIP_COUNT, FILTER_COUNT, WRITE_SKIP_COUNT

Job Runtime Identifiers

InstanceId ExecutionId StepExecutionId

JobOperator

Provides a set of operations to start, stop, restart, and inspect jobs.

Application Packaging Model

No unique packaging is required Jar War EJB Jar

Batch Artifact Loading

Implementation-specific loader Archive loader

META-INF Thread Context Class Loader

Job XML Loading

implementation-specific loader archive loader

IBM Extensions

Built on Liberty Profile as the Java Runtime Server Liberty Profile 8.5.5.6 and above

Extensions: Rest interface to JobOperator Command line client for job submission Multi-JVM support: Jobs or partitions can be

executed in a distributed topology

IBM JobRepository Implementation

In-memory File-Based Derby Relational database product

REST Interface to JobOperator

Provides a way to integrate with Schedulers

REST Submit

GET Job Instance Information

REST GET Job Execution Information

REST GET Step Execution Information

Multi-JVM Topology

Message Selectors

Use to pick up messages by executor servers.

Liberty Profile Server.xml

Questions