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GWT RPC implementation via Command pattern need only one! GWT RPC service for all kind of implementations:

GWT RPC service


            @RemoteServiceRelativePath("custom.rpc")
            public interface CustomRemoteService extends RemoteService {
                Response send(Request request) throws Exception;
            }

            public interface CustomRemoteServiceAsync {
                 void send(Request request, AsyncCallback callback);
            }

For all requests we have one single entry point at server:

Controller (Spring MVC)


            package com.bc.capman.web.common.server.controller;

            import com.bc.capman.web.common.server.rpc.RpcHandler;
            import com.bc.capman.web.common.shared.rpc.Request;
            import com.bc.capman.web.common.shared.rpc.Response;
            import com.bc.capman.web.common.shared.state.StateException;
            import com.google.gwt.user.server.rpc.RemoteServiceServlet;
            import org.springframework.web.servlet.ModelAndView;
            import org.springframework.web.servlet.mvc.Controller;

            import javax.inject.Inject;
            import javax.servlet.ServletContext;
            import javax.servlet.http.HttpServletRequest;
            import javax.servlet.http.HttpServletResponse;
            import java.util.HashMap;
            import java.util.Map;

            /**
            * User: Grigory Kislin
            * Date: 27/06/11
            */

            public class GwtRpcController extends RemoteServiceServlet implements Controller {
                private static Map, RpcHandler> requestMap = new HashMap<>();
    
                @Inject
                private ServletContext servletContext;
    
                @Override
                public ServletContext getServletContext() {
                    return servletContext;
                }
    
                @Override
                public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
                    doPost(request, response);
                    return null;
                }
    
                @Override
                public Response send(Request request) {
                    try {
                        logger.debug(...);
                        RpcHandler handler = requestMap.get(request.getClass());
                        return handler.handlerRequest(request);
                    } catch (StateException se) {
                        ...
                    } finally {
                        logger.debug(...);
                    }
                }
    
                public static void registerHandler(Class requestClass, RpcHandler handler) {
                    assert requestMap.get(requestClass) == null : "Handler with request " + requestClass + " already registered";
                    requestMap.put(requestClass, (RpcHandler) handler);
                }
            }

All handlers RpcHandler inherit RpcHandlerImpl base realization and registered own request in RpcHandlerImpl constructor:

Handler interface (Command)


            public interface RpcHandler {

                RS handlerRequest(RQ request) throws Exception;
            }

Handler base realization


            public abstract class RpcHandlerImpl implements RpcHandler {
                @Inject
                protected ContextHolder contextHolder;

                public RpcHandlerImpl(Class requestClass) {
                    GwtRpcController.registerHandler(requestClass, this);
                }
            }

So for the new custom request we need to create:

CustomRequest extends Request - java bean with all necessary information (do not forget default constructor for GWT serialization)
(Optional) CustomResponse extends Response - use custom or standard response for pass information to client
CustomHandler extends RpcHandlerImpl - handler for handle request and registered ourselves in constructor


                public CustomHandler() {
                   super(CustomRequest.class);
                }

All logging, time measurement, exception and context handling now located in 2 classes: GwtRpcController and RpcHandlerImpl.