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.

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

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

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

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
 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

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 GET Job Execution
Information

REST GET Step Execution
Information

Message Selectors
 Use to pick up messages by executor servers.

Java Batch

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