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 to 'com.google.gwt.user.client.rpc.IsSerializable' and did not have a custom field serializer.For security purposes, this type will not be serialized.: instance = xxx at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serialize(ServerSerializationStreamWriter.java:610) at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamWriter.writeObject(AbstractSerializationStreamWriter.java:129) at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter$ValueWriter$8.write(ServerSerializationStreamWriter.java:152) at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamWriter.serializeValue(ServerSerializationStreamWriter.java:534) at com.google.gwt.user.server.rpc.RPC.encodeResponse(RPC.java:609) at com.google.gwt.user.server.rpc.RPC.encodeResponseForSuccess(RPC.java:467) at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:564) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:188) at de.softconex.travicemanager.server.TraviceManagerServiceImpl.processCall(TraviceManagerServiceImpl.java:615) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62) at javax.servlet.http.HttpServlet.service(HttpServlet.java:710) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262) at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:419) at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:378) at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1508) at java.lang.Thread.run(Thread.java:619)

The application is normally running fine. The indicated class implements Serializable (the whole object graph).

So far the only patterns / observations are:

• we seem to have the issue only when the application is used inside an iframe

• the problem seems to happen when a new version of the application has been deployed

• running firefox in privacy mode (disabling all caches etc.) doesn't fix the problem

Any ideas?

Holger

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

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)