DWR with Google app engine

Question

I created one google app engine project. There I configured DWR(DirectWebRemoting). I have created one ajax functionality which will checks the username and password of the user. But it does give me any output rather it gives Error:

dwr is not defined
Source File: http://localhost:8081/dwr.jsp
Line: 16

Where as it works fine in Tomcat web application.

So My question is that does Google app engine not support DWR configuration?

Answer 1

DWR is compatible with GAE according to "Will it play in Java" (broken link. possibly: a list of GAE-compatible java libraries) page.

Several links to threads with proof of success and potential limitations:

• thread about "DWR 3 RC1" from "users@dwr.java.net"
• StackOverflow question "DWR sometimes die on the GAE server"

Most useful post in "DWR 3 RC1" thread is this one (about potential problems).

1. Do you require reverse ajax? (Current implementation uses a thread to clean up expired sessions. Current implementation uses javax.swing.event.EventListenerList which is blacklisted by GAE/J.)

2. Do you require file upload? (Can potentially write to disk)

3. Do you require file download? (Current implementation uses a thread to clean up expired downloads)

If you don't need anything from the above, then you could replace problematic classes with dummy implementation.