Workflow Module

This module allows you to define workflows that run steps either sequentially or via events.

The test folder contains an example workflow with 3 steps.

Building a Workflow

Each workflow should implement the Workflow interface:

public class DemoWorkflow implements Workflow {

    private SomeStepDefinedAsAService serviceStep;

    public static String NAME = "demo-workflow";

    public DemoWorkflow(SomeStepDefinedAsAService serviceStep) {
        this.serviceStep = serviceStep;
    }

    @Override
    public WorkflowBuilder getBuilder() {
        CompletedStep completedStep = new CompletedStep();
        return WorkflowBuilder
                .create()
                .addStep(this.serviceStep)
                .addStep(new SomeOtherStepThatIsntAService())
                .addStep(new CompletedStep())
                .onEvent("STEP_ONE_COMPLETED", serviceStep.getName())
                .onEvent("STEP_TWO_COMPLETED", completedStep.getName());
    }

    @Override
    public String getName() {
        return NAME;
    }
}

Note: onEvent() in workflows is optional. You can simply just use addStep if your workflow runs sequentially.

Once a workflow is built, when your application runs, it will automatically insert your workflow into the database and is ready for use. You can direct users to the /wf/{workflow-name} url to begin the workflow.

Steps

A workflow is composed of steps. Each step should output a StepResult object. For Web workflows, you can return a WebStepResult object.

If a StepResult returns isCompleted() == true, it will attempt to load the next step. Otherwise it will process the output of the StepResult.

Additionally, each Step should save an event that marks it as complete when it is finished processing. For instance, after a Form step has been posted and saved, a "FORM_COMPLETED" event should be stored so the workflow knows that this step is completed.

public class ThankYouStep implements Step {

    @Autowired
    private EventService eventService;

    private static final String COMPLETED_EVENT_NAME = "WORKFLOW_COMPLETED";

    @Override
    public StepResult runStep(WorkflowResult result) {
        eventService.createEvent(result, COMPLETED_EVENT_NAME, "Workflow Completed");
        ModelAndView view = new ModelAndView("thank-you");
        return new WebStepResult("THANK_YOU_LOADED", view, false);
    }

    @Override
    public String getName() {
        return "thank-you";
    }

    @Override
    public String getCompletedEventName() {
        return COMPLETED_EVENT_NAME;
    }

}

Each step can override the boolean isStepValid(WorkflowResult result) method. If isStepValid returns false, the step will be skipped.