Asynchronous processing

The following two examples show asynchronous processing in the Client and Server APIs:

• Asynchronous processing in the Client API:

  
  Client client = ClientBuilder.newClient();
  WebTarget target = client.target("http://example.org/customers/{id}");
  target.resolveTemplate("id", 123).request().async().get(
     new InvocationCallbackCustomer() {       
            @Override
             public void completed(Customer customer) { 
                // Do something 
             }       
            @Override 
             public void failed(Throwable throwable) {
                // Process error 
             } 
  }); 
  

• Asynchronous processing in the Server API:

  
  @Path("/async")
  public class MyResource{
  
            @GET
             public void getAsync(@Suspended final AsyncResponse asyncResponse){ 
                CompletionCallback callBack = new CompletionCallback(){		
  	                    @Override
  	                    public void onComplete(Throwable throwable) {
  	                          	...
  	                    }
  		             };		 
  	            asyncResponse.register(callBack);	    
  	            asyncResponse.resume("some Response");		    
  	         }
  }
  

The JAX-RS 2.0 implementation in Liberty supports EJB and the use of stateless and singleton session beans as root resource classes. When an EJB method is annotated with @Asynchronous, the EJB container automatically allocates the necessary resources for its execution. Thus, in this scenario, it is unnecessary to use an Executor to generate an asynchronous response. For example,

@Stateless
@Path("/")
class EJBResource {

	@GET @Asynchronous
	public void longRunningOp(@Suspended AsyncResponse ar) {
		executeLongRunningOp();
		ar.resume("Hello async world!");
	}
}

Explicit thread management is not needed in this case because that is under the control of the EJB container. The response is produced by calling resume on the injected AsyncResponse. Hence, the return type of longRunningOp is void.