JAX-RS - Asynchronous Processing with Timeout Handler

By default injecting AsyncResponse via @Suspended (last example), suspends the processing indefinitely (till we call AsyncResponse#resume()). The suspend timeout as well as a custom timeout handler can be specified using the AsyncResponse.setTimeout(long, TimeUnit) and AsyncResponse.setTimeoutHandler(TimeoutHandler) methods.

Example

A async resource method with timeout handling

@Path("/orders")
public class OrderResource {
    @GET
    public void getAllOrders(@Suspended final AsyncResponse ar) {
        ExecutorService es = Executors.newSingleThreadExecutor();

        ar.setTimeoutHandler(new TimeoutHandler() {
            @Override
            public void handleTimeout(AsyncResponse asyncResponse) {
                asyncResponse.resume("Processing timeout.");
                es.shutdown();
            }
        });

        ar.setTimeout(2, TimeUnit.SECONDS);
        es.submit(() -> {
            try {
                //Simulating a long running process
                Thread.sleep(4000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            ar.resume("all orders data....");
            es.shutdown();
        });
    }
}

The resource client

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();
        Response response = target.request().get(Response.class);
        String responseString = response.readEntity(String.class);
        System.out.println("response: " + responseString);
        System.out.println("time taken: " + (System.currentTimeMillis() - start));
        System.out.println("request returns");
    }
}

Output

response: Processing timeout.
time taken: 2717
request returns

Note

If the timeout value is reached and no timeout handler is registered, JAX-RS server side generates a ServiceUnavailableException with the status set to 503.

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