JAX-RS 2.1: Async improvements

Async improvements

In JAXRS 2.0, you can build an asynchronous RESTful APIs as the following.

@GET
public void getAsync(final @Suspended AsyncResponse res) {
 res.setTimeoutHandler(
   (ar) -> {
    ar.resume(Response.status(Response.Status.SERVICE_UNAVAILABLE)
      .entity("Operation timed out --- please try again.").build());
   }
 );
 res.setTimeout(1000, TimeUnit.MILLISECONDS);
 executor.submit(() -> {
  //do long run operations.
  try {
   LOG.log(Level.INFO, " execute long run task in AsyncResource");
   //Thread.sleep(new Random().nextInt(1005));
   Thread.sleep(500);
  } catch (InterruptedException ex) {
   LOG.log(Level.SEVERE, "error :" + ex.getMessage());
  }
  res.resume(Response.ok("asynchronous resource").build());
 });
}

Inject @Suspended AsyncResponse res as the method parameter, call res.resume() to return response result asynchronously.
Or combined with EJB @Asynchronous.

@GET
@Asynchronous
public void getAsync(final @Suspended AsyncResponse res) {

 //perform long run operations.
 try {
  LOG.log(Level.INFO, " execute long run task in EjbAsyncResource");
  Thread.sleep(500);
 } catch (InterruptedException ex) {
  LOG.log(Level.SEVERE, "error :" +ex.getMessage());
 }

 res.resume(Response.ok("Asynchronus EJB resource").build());
}

JAXRS 2.1 allow you return a CompletionStage directly.

@GET
public CompletionStage<String> getAsync() {
 CompletionStage<String> cs = CompletableFuture
   .<String>supplyAsync(
     () -> {
      try {
       LOG.log(Level.INFO, " execute long run task in CompletionStageResource");
       Thread.sleep(500);
      } catch (InterruptedException ex) {
       LOG.log(Level.SEVERE, "error :" +ex.getMessage());
      }
      return "return CompletableFuture instead of @Suspended";
     }
       // , executor
   );

 return cs;
}

Grab the source codes from my github account, and have a try.