如何编写Java EJB异步服务？

Question

I tried to do this

@Consumes(APPLICATION_XML)
@Produces(APPLICATION_XML)
public class TestService {
    @POST
    @Path("querymember")
    @Asynchronous
    public Future<String> queryMemberAysnc(Member member) {
        return new AsyncResult<>(businessLogic.query(member));
    }
}

When I do this in synchronous way, it works fine. But once I change it to async, it is giving me "org.apache.cxf.jaxrs.interceptor.JAXRSOutInterceptor.writeResponseErrorMessage No message body writer has been found for response class AsyncResult."

I couldn't find any other example on writing an aysnc operation with EJB. Any hint on how I can fix this in a right way?

Answer 1

The asynchronous method should be implemented inside EJB Session Bean, because web service call result of type Future make no sence.

So, the example idea could be: 1. Implement EJB Session Bean, with @Asynchronous method 2. Implement method in your web service, which will call asynchronous method -> save returned 'Future' object somewhere in your storage by key (static Map, etc) -> return this key to client 3. Implement method in your web service for getting a result by key, which will retreive 'Future' object by key from your storage -> check if Future have result -> return the result to client

The client should periodically check for results, until asynchronous method invocation is finished, and result is returned.