Calling a long running process asynchronously on a button click in JSF

Question

I want to execute a stored proc by clicking on a button developed in JSF and Java. The proc takes roughly around 30 minutes in execution.

When the user clicks on this button, s/he should get a default message like -

Data is being processed. Kindly login after 60 minutes to check the data.

Now when we click on the button, the UI Page hangs for the time when the proc is getting executed.

Is there a workaround to show this default message and run the proc in the backend?

Answer 1

Just trigger an @Asynchronous EJB method. It'll fire and forget a separate thread and the bean action method will immediately return.

@Named
public class Bean {

    @EJB
    private Service service;

    public void submit() {
        service.asyncDoSomething();

        // Add message here.
    }

}

@Stateless
public class Service {

    @Asynchronous
    public void asyncDoSomething() {
        // ...
    }

}

See also:

• Is it safe to start a new thread in a JSF managed bean?
• How can server push asynchronous changes to a HTML page created by JSF?

Answer 2

You can call a method on click of button which can use Future or FutureTask, available in the java.util.concurrent package. Former is an interface, the latter is an implementation of the Future interface.

By using "Future" in your code, your asynchronous task will be executed immediately with the promise of the result being made available to the calling thread in the future.

Have a look at this link: Is it safe to start a new thread in a JSF managed bean?
Also have a look at this link: https://codereview.stackexchange.com/questions/39123/efficient-way-of-having-synchronous-and-asynchronous-behavior-in-an-application