Forgive me if this has been answered already...I looked around and found only this one unanswered post: http://groups.google.com/group/google-appengine-java/browse_thread/thread/636e7cb54d7ca505
It seems that if I create a proxy object and put it into the session, then I run into deserialization troubles when the server tries to restore the session on the next request. To break this down to the simplest thing possible, I created an interface called Foo: public interface Foo { void doFoo(); } And an equally simple implementation: public class FooImpl implements Foo, Serializable { public void doFoo() { System.out.println("Foo is good"); } } I then created a proxy object for it and put the proxy into the session and redirected to another page. At that point, I get the following: javax.servlet.ServletException: java.lang.RuntimeException: java.lang.ClassNotFoundException: org.springframework.social.connect.web.Foo at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java: 251) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java: 152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java: 542) at org.mortbay.jetty.HttpConnection $RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java: 76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java: 135) at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java: 260) at com.google.apphosting.base.RuntimePb$EvaluationRuntime $2.handleRequest(RuntimePb.java:9673) at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java: 422) at com.google.net.rpc.impl.Server$RpcTask.runInContext(Server.java: 573) at com.google.tracing.TraceContext$TraceContextRunnable $1.run(TraceContext.java:448) at com.google.tracing.TraceContext.runInContext(TraceContext.java: 688) at com.google.tracing.TraceContext $AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java: 326) at com.google.tracing.TraceContext $AbstractTraceContextCallback.runInInheritedContext(TraceContext.java: 318) at com.google.tracing.TraceContext $TraceContextRunnable.run(TraceContext.java:446) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java: 1110) at java.util.concurrent.ThreadPoolExecutor $Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:636) Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: org.springframework.social.connect.web.Foo at com.google.apphosting.runtime.jetty.SessionManager.deserialize(SessionManager.java: 386) at com.google.apphosting.runtime.jetty.MemcacheSessionStore.getSession(MemcacheSessionStore.java: 31) at com.google.apphosting.runtime.jetty.SessionManager.loadSession(SessionManager.java: 320) at com.google.apphosting.runtime.jetty.SessionManager.getSession(SessionManager.java: 294) at org.mortbay.jetty.servlet.AbstractSessionManager.getHttpSession(AbstractSessionManager.java: 237) at org.mortbay.jetty.servlet.SessionHandler.setRequestedId(SessionHandler.java: 246) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java: 136) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java: 765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java: 418) at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java: 249) ... 19 more Caused by: java.lang.ClassNotFoundException: org.springframework.social.connect.web.Foo at java.net.URLClassLoader$1.run(URLClassLoader.java:217) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:205) at java.lang.ClassLoader.loadClass(ClassLoader.java:321) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at com.google.apphosting.runtime.security.RuntimeClassLoader.loadFilteredClass(RuntimeClassLoader.java: 258) at com.google.apphosting.runtime.security.RuntimeClassLoader.loadPrivilegedClass(RuntimeClassLoader.java: 201) at com.google.apphosting.runtime.security.RuntimeClassLoader.loadClass(RuntimeClassLoader.java: 155) at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at java.io.ObjectInputStream.resolveProxyClass(ObjectInputStream.java: 693) at java.io.ObjectInputStream.readProxyDesc(ObjectInputStream.java: 1548) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java: 1510) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java: 1749) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:368) at java.util.HashMap.readObject(HashMap.java:1047) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java: 57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java: 43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java: 991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java: 1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java: 1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java: 1963) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java: 1887) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java: 1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:368) at com.google.apphosting.runtime.jetty.SessionManager.deserialize(SessionManager.java: 382) ... 28 more Does GAE not support placing proxy objects into the session? -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. 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