Asynchronous JAX-RS - RESTful Java with JAX-RS 2.0 - page 190

Chapter 13. Asynchronous JAX-RS

Another interesting new feature introduced in JAX-RS 2.0 is asynchronous request and re-
sponse processing both on the client and server side. If you are mashing together a lot of data
from different websites or you have something like a stock quote application that needs to
push events to hundreds or thousands of idle blocking clients, then the JAX-RS 2.0 asyn-
chronous APIs are worth looking into.

AsyncInvoker Client API

The client asynchronous API allows you to spin off a bunch of HTTP requests in the back-
ground and then either poll for a response, or register a callback that is invoked when the
HTTP response is available. To invoke an HTTP request asynchronously on the client, you
interact with the javax.ws.rs.client.AsyncInvoker interface or the submit() methods
on javax.ws.rs.client.Invocation . First, let's take a look at polling HTTP requests that
are run in the background.

Using Futures

The AsyncInvoker interface has a bunch of methods that invoke HTTP requests asynchron-
ously and that return a java.util.concurrent.Future instance. You can use the AsyncIn-
voker methods by invoking the async() method on the Invocation.Builder interface.

package package javax . ws . rs . client ;

public public interface AsyncInvoker {

Future < Response > get ();
< T > Future < T > get ( Class < T > responseType );

interface AsyncInvoker

Future < Response > put ( Entity <?> entity );
< T > Future < T > put ( Entity <?> entity , Class < T > responseType );

Future < Response > post ( Entity <?> entity );
< T > Future < T > post ( Entity <?> entity , Class < T > responseType );

Future < Response > delete ( Entity <?> entity );
< T > Future < T > delete ( Entity <?> entity , Class < T > responseType );

...

}