How to develop a Workflow Definition in Java

In the Temporal Java SDK programming model, a Workflow definition comprises a Workflow interface annotated with @WorkflowInterface and a Workflow implementation that implements the Workflow interface.

The Workflow interface is a Java interface and is annotated with @WorkflowInterface. Each Workflow interface must have only one method annotated with @WorkflowMethod. The method name can be used to denote the Workflow Type.

// Workflow interface
@WorkflowInterface
public interface YourWorkflow {

    @WorkflowMethod
    String yourWFMethod(Arguments args);
}

However, when using dynamic Workflows, do not specify a @WorkflowMethod, and implement the DynamicWorkflow directly in the Workflow implementation code.

The @WorkflowMethod identifies the method that is the starting point of the Workflow Execution. The Workflow Execution completes when this method completes.

You can create interface inheritance hierarchies to reuse components across other Workflow interfaces. The interface inheritance approach does not apply to @WorkflowMethod annotations.

A Workflow implementation implements a Workflow interface.

// Define the Workflow implementation which implements our getGreeting Workflow method.
  public static class GreetingWorkflowImpl implements GreetingWorkflow {
      ...
    }
  }

To call Activities in your Workflow, call the Activity implementation.

Use ExternalWorkflowStub to start or send Signals from within a Workflow to other running Workflow Executions.

You can also invoke other Workflows as Child Workflows with Workflow.newChildWorkflowStub() or Workflow.newUntypedChildWorkflowStub() within a Workflow Definition.

Use DynamicWorkflow to implement Workflow Types dynamically. Register a Workflow implementation type that extends DynamicWorkflow to implement any Workflow Type that is not explicitly registered with the Worker.

The dynamic Workflow interface is implemented with the execute method. This method takes in EncodedValues that are inputs to the Workflow Execution. These inputs can be specified by the Client when invoking the Workflow Execution.

public class MyDynamicWorkflow implements DynamicWorkflow {
   @Override
    public Object execute(EncodedValues args) {
    }
}