Comments on Enterprise Java - Digital Ascent: GWT-RPC with Spring 2.x

Interestingly, I came up with a similar solution w...

2008-04-22T08:21:00.000-07:00

Interestingly, I came up with a similar solution while experimenting with GWT and Spring. I think the cleanest way to integrate Spring and GWT is indeed by using a Handler and HandlerAdapter pair...
I posted my solution @ http://forum.springframework.org/showthread.php?t=52805
Also, it seems GWT is going to pull some of the functions out of RemoteServiceServlet. That should enable you to remove the dependency on RemoteServiceServlet in your HandlerAdapter.

Really like this implementation!I've been posting ...

2008-02-15T06:12:00.000-08:00

Really like this implementation!

I've been posting on my blog a Spring and GWT tutorial for basic beginning steps, further on your guide will prove very useful!

RemoteServiceServlet...gone :)

Really nice work. All we need now is a good extens...

2008-02-15T05:51:00.000-08:00

Really nice work.
All we need now is a good extension point for the web.xml that gets re-generated.

I am adding my config into the tomcat/conf/web.xml - this one does not get re-generated (GWiT 1.4).

How do you setup your projects?

Hi Martin,Good catch - because we subclass the Rem...

2007-11-29T06:59:42.031-08:00

Hi Martin,

Good catch - because we subclass the RemoteServiceServlet but don't actually use it as a Servlet, it doesn't have a ServletContext. The original code didn't need/use the ServletContext and never encountered this problem.

An alternate solution would be to use ServletContextAware to inject the servlet context.

I fixed my issue for 1.4.60, but if you have a bet...

2007-11-29T02:31:00.000-08:00

I fixed my issue for 1.4.60, but if you have a better solution, please let me know.

package com.mwaysolutions.gofer2.gwt;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.HandlerAdapter;
import org.springframework.web.servlet.ModelAndView;

import com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException;
import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.SerializationException;
import com.google.gwt.user.server.rpc.RPC;
import com.google.gwt.user.server.rpc.RPCRequest;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;

/**
* Spring HandlerAdapter to dispatch GWT-RPC requests. Relies on handlers
* registered by GwtAnnotationHandlerMapper
*
* @author Chris Lee, Martin Zdila
*
*/
public class GwtRcpEndPointHandlerAdapter extends RemoteServiceServlet implements HandlerAdapter, ApplicationContextAware {

private static ThreadLocal< Object> handlerHolder = new ThreadLocal< Object>();
private static final long serialVersionUID = -7421136737990135393L;
private ApplicationContext applicationContext;

@Override
public long getLastModified(final HttpServletRequest request, final Object handler) {
return -1;
}

@Override
public ModelAndView handle(final HttpServletRequest request, final HttpServletResponse response, final Object handler) throws Exception {
try {
// store the handler for retrieval in processCall()
handlerHolder.set(handler);
doPost(request, response);
} finally {
// clear out thread local to avoid resource leak
handlerHolder.set(null);
}

return null;
}

protected Object getCurrentHandler() {
return handlerHolder.get();
}

@Override
public boolean supports(final Object handler) {
return handler instanceof RemoteService /*&& handler.getClass().isAnnotationPresent(GwtRpcEndPoint.class)*/;
}

@Override
public String processCall(final String payload) throws SerializationException {
/*
* The code below is borrowed from RemoteServiceServet.processCall, with
* the following changes:
*
* 1) Changed object for decoding and invocation to be the handler
* (versus the original 'this')
*/

try {
final RPCRequest rpcRequest = RPC.decodeRequest(payload, getCurrentHandler().getClass() /* this.getClass() */, this);
return RPC.invokeAndEncodeResponse(getCurrentHandler() /* this */, rpcRequest.getMethod(), rpcRequest.getParameters(), rpcRequest.getSerializationPolicy());
} catch (final IncompatibleRemoteServiceException ex) {
getServletContext().log("An IncompatibleRemoteServiceException was thrown while processing this call.", ex);
return RPC.encodeResponseForFailure(null, ex);
}
}

@Override
public ServletContext getServletContext() {
return ((WebApplicationContext) applicationContext).getServletContext();
}

@Override
public void setApplicationContext(final ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}

}

hi chrisusing GWT 1.4.60 and Tomcat 6.0.13GwtRcpEn...

2007-11-29T00:51:00.000-08:00

hi chris

using GWT 1.4.60 and Tomcat 6.0.13

GwtRcpEndPointHandlerAdapter.getServletContext() causes NullPointerException because servlet's config is never initialized. How come that you didn't meet the same problem?

@Chris. This is a pretty slick example of the new...

2007-11-14T11:23:00.000-08:00

@Chris. This is a pretty slick example of the new Spring 2.5 features.

@Scott. The Spring DispatcherServlet puts the request into a ThreadLocal accessible indirectly via the RequestContextHolder.getRequestAttributes()

I haven't wired in direct access for the request o...

2007-11-14T07:55:31.153-08:00

I haven't wired in direct access for the request or session objects yet - that will come shortly, either in the form of a static utility class or a GwtRequestAware interface.

My preference is to inject Spring request or session scoped beans (http://static.springframework.org/spring/docs/2.5.x/reference/beans.html#beans-factory-scopes-other)

Looks interesting Chris. Is there any way to get a...

2007-11-14T05:24:00.000-08:00

Looks interesting Chris. Is there any way to get access to the request or session objects when using this approach?