How to Build and Run Complex Java Workflows with Easy Work

What is Easy Work?

Easy Work is a Java workflow engine that provides a concise API and modular components for creating composable workflows.

Core Concepts

Work units are represented by the Work interface, and a workflow is represented by the WorkFlow interface. Easy Work offers six implementations of WorkFlow, including RepeatFlow, SequentialFlow, ParallelFlow, and ConditionalFlow.

Creating a Work

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;
    }
}

Building a Sample Workflow

The example workflow prints “a” three times, then prints “b c d” in order, runs “e” and “f” in parallel, chooses “g” or “h” based on the parallel result, and finally prints “z”. flow1 – RepeatFlow of “a” three times flow2 – SequentialFlow of “b c d” flow3 – ParallelFlow of “e f” flow4 – ConditionalFlow that runs flow3 then g or

h

flow5

– SequentialFlow that composes the previous flows and ends with “z”

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());

Pausing and Resuming Workflows

Since version 1.0.5 Easy Work supports breakpoints. A breakpoint can be set on any work unit, for example on work “c”. Execution can be paused at the breakpoint and later resumed.

SequentialFlow flow = aNewSequentialFlow(
    aNewRepeatFlow(a).times(3),
    aNewSequentialFlow(b, aNamePointWork(c).point("C_BREAK_POINT"), d),
    aNewConditionalFlow(
        aNewParallelFlow(e, f).withAutoShutDown(true)
    ).when(WorkReportPredicate.COMPLETED, g, h),
    z
);
// pause at breakpoint
flow.execute("C_BREAK_POINT");
System.out.println("execute to the break point `C_BREAK_POINT`");
// resume
flow.execute();

JSON‑Based Workflow Definition

From version 1.0.8 workflows can be described in JSON. The following snippet corresponds to the earlier example.

{
  "type":"sequential",
  "works":[
    {"type":"repeat","times":3,"work":{"type":"work.PrintMessageWork","message":"a"}},
    {"type":"sequential","works":[
        {"type":"work.PrintMessageWork","message":"b"},
        {"type":"work.PrintMessageWork","message":"c"},
        {"type":"work.PrintMessageWork","message":"d"}
    ]},
    {"type":"conditional","decide":{
        "type":"parallel","autoShutdown":true,"works":[
            {"type":"work.PrintMessageWork","message":"e"},
            {"type":"work.PrintMessageWork","message":"f"}
        ]},
      "predicate":{"left":"$status","operator":"eq","right":"COMPLETED"},
      "trueWork":{"type":"work.PrintMessageWork","message":"g"},
      "falseWork":{"type":"work.PrintMessageWork","message":"h"}},
    {"type":"work.PrintMessageWork","message":"z"}
  ]
}

Deserialization and execution are performed with:

String json = ResourceReader.readJSON("json/example.json");
SequentialFlow sequentialFlow = (SequentialFlow) deserialize(json);
sequentialFlow.execute(new WorkContext());

https://gitee.com/ifrog/easy-work