Long running and multi-step Jobs

ExecutionStep overview

Some of the use cases for `ExecutionStep` are as follows:

• Long Running Jobs: These are jobs that take several minutes or hours to execute.
• Multi-step Jobs: These are jobs which organise the execution through multiple logical steps (e.g.: transcode a file, then create Flex Asset and add Technical Metadata)

Using `ExecutionStep`, plugin developers can implement an `ActionExecutor` that delegates async behaviour via `ExecutionStep` active component.

• After `ActionExecutor.execute()` returns, `ExecutionStep.execute()` will be called periodically.
• The plugin will receive `ExecutionStepData` associated to the job context and can execute step logic to continue running / complete / fail / cancel the job.

JEF will use `ExecutionStep` to orchestrate and ease the development of above steps in independent classes

• The steps can be defined linearly, or could be a dynamic graph of options based on the logic of the plugin and current status.
• `ExecutionStep` can also be leveraged to reuse logic across multiple plugins, or orchestrate different flows depending on plugin logic or retry status.

See https://github.com/dalet-oss/flex-jefexampleexecutor-service/tree/master/Service/src/main/java/com/ooyala/flex/jefexampleexecutor/actions/impl/executionstep

Developing with ExecutionStep: simple example

Quick start

• `ExecutionStepConfiguration` class is registered in the `ActionExecutor` annotation to indicate that this Action is using `ExecutionStep`.
• `ExecutionStepData` is a POJO required to store job execution data. It could be empty if no data is required across different execution step.
• `ExecutionStepData` is passed with every call to `ExecutionStep` to execute. This allows the job executor to resume in a different job executor microservice, in case one instance fails during the lifetime of the job.
• `ActionExecutor.execute(ExecutionStepData)` will be called first time to initiate the job execution
• `ExecutionStep.execte(ExectuionStepData)` implementation is called periodically during the life of the job.

See https://github.com/dalet-oss/flex-jefexampleexecutor-service/tree/master/Service/src/main/java/com/ooyala/flex/jefexampleexecutor/actions/impl/executionstep/simple

Multiple functional steps

In addition to above simple example, a plugin developer can define multiple functional steps with the following implementation:

• `Class<StepExampleExecutionStep1> getExecutionStepClass().ExecutionStepConfiguration` defines which of all the existing ExecutionStep beans is the first one to start the execution.
• `Class<? extends ExecutionStep> ExecutionStep.getNextStep(StepExampleActionStepData actionStepData)` defines which is the next step to run based on stepData. Notice that this could be resolved based on dynamic logic.

See https://github.com/dalet-oss/flex-jefexampleexecutor-service/tree/master/Service/src/main/java/com/ooyala/flex/jefexampleexecutor/actions/impl/executionstep/multiple

This is all you need to organise your plugin execution into smaller, reusable functional components.