Work Coordination - rife2/rife2 GitHub Wiki

With the work units that were defined in the previous section we can create a workflow that coordinates the work.

Setting up the workflow

We can for instance integrate the workflow into a RIFE2 site and start the NotificationWork and PaymentWork units during setup. These will then be ready to receive triggered events.

For instance:

public class HelloWorkflow extends Site {
    enum WorkType {
        NOTIFICATION, PAYMENT, CONFIRMATION
    }

    final Workflow workflow = createWorkflow();

    // ... NotificationWork, PaymentWork and ConfirmationWork classes ...
    
    public void setup() {
        workflow.start(new NotificationWork());
        workflow.start(new PaymentWork());

        // ... routes ...
    }

    public static void main(String[] args) {
        new Server().start(new HelloWorkflow());
    }
}

NOTE: when integrating workflows with the web engine, it's recommended to use the Site's createWorkflow() method in order to properly slot the workflow into the hierarchical properties. When running standalone, you can simply use new Workflow() to create a new instance.

Send events from elements

As a final step in our example, we're creating three routes and three elements that will directly send events.

For instance:

public class HelloWorkflow extends Site {
    // ...    
    public void setup() {
        // ... workflow setup

        get("/notification", c -> workflow.trigger(NOTIFICATION, c.parameter("account")));
        get("/payment", c -> workflow.trigger(PAYMENT, c.parameter("account")));
        get("/confirm", c -> workflow.inform(CONFIRMATION, c.parameter("account")));
    }
    // ... main
}

You'll notice that there are two ways to send events:

workflow.trigger(Object type, Object data); // Sends event that will be queued if nobody is waiting
workflow.inform(Object type, Object data);  // Sends event that will be lost if nobody is waiting

The distinction between trigger and inform matters. For instance, consider the CONFIRMATION event, if we would use trigger here, any confirmation sent before the PAYMENT event is triggered, will be added to a queue. As soon as the PaymentWork class calls workflow.start(new ConfirmationWork(event.getData()));, a ConfirmationWork instance will pause for the CONFIRMATION event and find one in the queue, resuming immediately. When using inform, that earlier confirmation will not be queued but be discarded instead. ConfirmationWork will then not resume immediately but pause until the confirmation comes through afterwards.

Test the example

In our example, each element will send a dedicated event with the value of the account query string parameter.

For instance when you type this in your console

curl "http://localhost:8080/notification?account=test"

The application will print:

Sending notification email test

Typing this:

curl "http://localhost:8080/payment?account=test"

Will print:

Waiting for confirmation test
Sending notification email test

And finally typing this:

curl "http://localhost:8080/confirm?account=test"

Will print:

Sending payment test

You can find the full example in the RIFE2 GitHub repository.

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