Easy Work - The simple, easy-used, stupid workflow engine for Java

Source: Dev.to

What is Easy Work?

Easy Work is a workflow engine for Java. It provides concise APIs and building blocks for creating and running composable workflows.

In Easy Work, work units are represented by the Work interface, while workflows are represented by the WorkFlow interface.

Easy Work provides six implementation methods for the WorkFlow interface:

Those are the only basic flows you need to know to start creating workflows with Easy Work. You don’t need to learn a complex notation or concepts, just a few natural APIs that are easy to think about.

How does it work?

Define a work unit

public class PrintMessageWork implements Work {

    private final String message;

    public PrintMessageWork(String message) {
        this.message = message;
    }

    @Override
    public String execute(WorkContext workContext) {
        System.out.println(message);
        return message;
    }
}

This unit of work prints a given message to the standard output.

Build a workflow

We want a workflow that:

• prints a three times
• then prints b, c, d in sequence
• then prints e and f in parallel
• if both e and f succeed, prints g; otherwise prints h
• finally prints z

The workflow can be illustrated as follows:

• flow1 → RepeatFlow that prints a three times.
• flow2 → SequentialFlow that prints b, c, d in order.
• flow3 → ParallelFlow that prints e and f in parallel.
• flow4 → ConditionalFlow; executes flow3 and, if the result is successful (Complete), executes g, otherwise h.
• flow5 → SequentialFlow that runs flow1, flow2, flow4, and finally z.

Implementation

PrintMessageWork a = new PrintMessageWork("a");
PrintMessageWork b = new PrintMessageWork("b");
PrintMessageWork c = new PrintMessageWork("c");
PrintMessageWork d = new PrintMessageWork("d");
PrintMessageWork e = new PrintMessageWork("e");
PrintMessageWork f = new PrintMessageWork("f");
PrintMessageWork g = new PrintMessageWork("g");
PrintMessageWork h = new PrintMessageWork("h");
PrintMessageWork z = new PrintMessageWork("z");

WorkFlow flow = aNewSequentialFlow(
    aNewRepeatFlow(a).times(3),
    aNewSequentialFlow(b, c, d),
    aNewConditionalFlow(
        aNewParallelFlow(e, f).withAutoShutDown(true)
    ).when(
        WorkReportPredicate.COMPLETED,
        g,
        h
    ),
    z
);
aNewWorkFlowEngine().run(flow, new WorkContext());

This example is simple, but it demonstrates how to compose workflows with Easy Work.

You can view more test cases in test/java.

For additional details, see the wiki.