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

Question

Hello

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

I was getting a SerializationException also but I was also seeing this error showing up right before the serialization exception:

[uptimereports/2.340102563369350884].: Example : error : cannot find template registration-confirmation.vm

It turned out to be a problem finding my velocity template. Once I fixed that problem the SerializationException stopped showing up, so if you follow Kerem's advice and still have problems, look for other exceptions in your log.

Answer 3

http://code.google.com/intl/fr/webtoolkit/doc/latest/FAQ_Server.html#Does_the_GWT_RPC_system_support_the_use_of_java.io.Serializable

Answer 4

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