JWorkflow

JWorkflow is a light weight workflow library for Java. It supports pluggable persistence and concurrency providers to allow for multi-node clusters.

Installing

Using Maven

Add jworkflow to your POM file as a dependency.

<dependencies>
    <dependency>
        <groupId>net.jworkflow</groupId>
        <artifactId>jworkflow</artifactId>
        <version>0.5-SNAPSHOT</version>
    </dependency>
</dependencies>

Using Gradle

dependencies { 
    compile 'net.jworkflow:jworkflow:0.5-SNAPSHOT'
}

Documentation

See Tutorial here.

Fluent API

Define your workflows with the fluent API.

public class HelloWorkflow implements Workflow {
   @Override
    public void build(WorkflowBuilder builder) {
        
        builder
            .startsWith(Task1.class)
            .then(Task2.class)                
            .then(Task3.class);        
    }    
}
...
...
public class Task1 implements StepBody {

    @Override
    public ExecutionResult run(StepExecutionContext context) {
        System.out.println("Hello world");
        return ExecutionResult.next();
    }    
}

JSON Workflow Definitions

Define your workflows in JSON

{
  "id": "HelloWorld",
  "version": 1,
  "steps": [
    {
      "id": "hello",
      "stepType": "com.myapp.Step1",
      "nextStepId": "bye"
    },        
    {
      "id": "bye",
      "stepType": "com.myapp.Step2"
    }
  ]
}

Sample use cases

• New user workflow

public class MyData {    
    public String email;
    public String password;
    public String userId;
}


public class MyWorkflow implements Workflow<MyData> {

    ...

    @Override
    public void build(WorkflowBuilder<MyData> builder) {
        builder
            .startsWith(CreateUser.class)  
                .input((step, data) -> step.email = data.email)
                .input((step, data) -> step.password = data.password)
                .output((step, data) -> data.userId = step.userId)
            .then(SendConfirmationEmail.class)
                .waitFor("confirmation", data -> data.userId)
            .then(UpdateUser.class)
                .input((step, data) -> step.userId = data.userId);
    }    
}

• Saga Transactions

public class MyWorkflow implements Workflow<MyData> {

    ...

    @Override
    public void build(WorkflowBuilder<MyData> builder) {
        builder
            .startsWith(CreateCustomer.class)  
            .then(PushToSalesforce.class)
                .onError(ErrorBehavior.RETRY)
            .then(PushToERP.class)
                .onError(ErrorBehavior.RETRY, Duration.ofMinutes(30));
    }    
}

builder
    .startsWith(LogStart.class)  
    .saga(saga -> saga
        .startsWith(Task1.class)
            .compensateWith(UndoTask1.class)
        .then(Task2.Class)
            .compensateWith(UndoTask2.class)
        .then(Task3.Class)
            .compensateWith(UndoTask3.class)
    )
    .onError(ErrorBehavior.RETRY, Duration.ofMinutes(30));
    .then(LogEnd.class);

Persistence

Since workflows are typically long running processes, they will need to be persisted to storage between steps. There are several persistence providers available as seperate packages.

• Memory Persistence Provider (Default provider, for demo and testing purposes)
• MongoDB
• Amazon DynamoDB
• (more to come soon...)

Multi-node clusters

By default, the WorkflowHost service will run as a single node using the built-in queue and locking providers for a single node configuration. Should you wish to run a multi-node cluster, you will need to configure an external queueing mechanism and a distributed lock manager to co-ordinate the cluster. These are the providers that are currently available.

Queue Providers

• SingleNodeQueueProvider (Default built-in provider)
• RabbitMQ
• Redis
• AWS Simple Queue Service

Distributed lock managers

• SingleNodeLockProvider (Default built-in provider)
• Redis
• Amazon DynamoDB
• (more to come soon...)

Samples

Hello World

Passing Data

If condition

Responding to external events

Parallel ForEach

While loop

Saga Transactions

JSON Workflows

Contributors

• Daniel Gerlag - Initial work

License

This project is licensed under the MIT License - see the LICENSE.md file for details