JAX-RS - Asynchronous Client

The JAX-RS client API supports asynchronous request processing. By default, invocations are synchronous but can be set to run asynchronously by calling the Invocation.Builder.async() method and registering an instance of InvocationCallback.

Example

A resource with async processing

@Path("/orders")
public class OrderResource {

    @GET
    public void getAllOrders(@Suspended final AsyncResponse ar) {
        ExecutorService es = Executors.newSingleThreadExecutor();
        es.submit(() -> {
            try {
                //Simulating a long running process
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            ar.resume("all orders data....");
            es.shutdown();
        });
    }
}

The resource client with async callback

public class OrderClient {

    public static void main(String[] args) throws Exception {
        Client client = ClientBuilder.newBuilder().build();
        WebTarget target =
                client.target("http://localhost:8080/orders");
        long start = System.currentTimeMillis();
        target.request().async().get(new InvocationCallback<Response>() {
            @Override
            public void completed(Response response) {
                String responseString = response.readEntity(String.class);
                System.out.println("response: " + responseString);
                System.out.println("time taken: " + (System.currentTimeMillis() - start));
            }

            @Override
            public void failed(Throwable throwable) {
                throwable.printStackTrace();
            }
        });
        System.out.println("request returns");
    }
}

Output

request returns
response: all orders data....
time taken: 2508

Note that, in above example (as compare to this example), the main method exits before getting the response.

Example Project

Dependencies and Technologies Used:

• jersey-server 2.25.1: Jersey core server implementation.
• jersey-container-servlet 2.25.1: Jersey core Servlet 3.x implementation.
• JDK 1.8
• Maven 3.3.9