Core component

Job  - A Job encapsulates all the Steps and associated configuration that belong to the batch job.

JobInstance - A JobInstance represents a uniquely identifiable Job run. A Job may have multiple JobInstances associated with it.

JobParameters 

• JobParameters are input values to the Job and can be used as reference data during Job execution as well as contribute to the JobInstance identity.

• JobParameters are key/value pairs and can be of type String, Date, Double, Long or a JobParameter.

JobExecution 

• A JobExecution refers to a single attempt to run a Job. A JobExecution may result in a completion or failure. 

• A JobInstance will not be considered completed unless the JobExecution completes successfully.

Step 

• A Step encapsulates all the necessary information needed to define and control the batch processing for that phase of the batch job. 

• Steps are independent of each other and can participate in “chunk oriented processing or execute a custom Tasklet implementation.

StepExecution - It represents an attempt to execute a Step and contains meta-data such as commit counts and access to the ExecutionContext.

ExecutionContext

• An ExecutionContext is a collection of key/value pairs that are persisted by the framework and provide a place to store persistent data that is scoped to a StepExecution or JobExecution. 

• This storage is useful for example in stateful ItemReaders where the current row being read from needs to be recorded.

JobRepository - It provides the CRUD persistence operations for all Job related metadata.

JobLauncher  - It provides the ability to run a Job with a provided set of JobParameters.