GWT - occasional com.google.gwt.user.client.rpc.SerializationException

Question

we are haunted by occasional occurences of exceptions such as:

com.google.gwt.user.client.rpc.SerializationException: Type \'xxx\' was not assignable

Answer 1

did you check http://code.google.com/webtoolkit/doc/latest/tutorial/RPC.html#serialize the article says: It has a default (zero argument) constructor with any access modifier (e.g. private Foo(){} will work)

I'm allways forgetting zeroargument const. when I am making a serializable object :D

Answer 2

If you are running on JBoss, this might be due to the fact that the previously deployed application is not deleted when undeployed. To fix this, you must modify the following file in JBoss: ${JBOSS_HOME}/server/default/deployers/jbossweb.deployer/META-INF/war-deployers-jboss-beans.xml and set the following attribute to true: deleteWorkDirOnContextDestroy

When the previously deployed application is not cleaned up, GWT can be confused about which RPC file it needs to load and you end up with those SerializationException

Answer 3

I encountered the problem when I used Tomcat6 + Devmode in Ubuntu Lucid amd64. Using com.google.gwt.user.client.rpc.IsSerializable instead of java.io.Serializable seemed solved the problem.

Answer 4

I had the same problem and I found a solution from another person:

"There is a possibility that you have a class which implements Serializable and you have an attribute field within that class which is not Serializable hence you might be getting this exception."

Many thanks to that person :)

My advice is to make all fields (which are not primitive types) in your class to implement Serializable also! This solved my problem.

Answer 5

So the RPC files are unique because they are loaded by servlets as well as being used in GWT. See http://code.google.com/webtoolkit/release-notes.html#Release_Notes_1_4_59 where it says "This file must be deployed to your web server as a public resource, accessible from a RemoteServiceServlet via ServletContext.getResource()"

Is it possible the new application is being reloaded dynamically and getResource is failing in some way? Does restarting the application fix things?

Answer 6

Very possible reason - older version of client is still cached in browser. It sends rpc requests, but server is already restarted and have newer versions of rpc files (*.symbolMap)