I am having trouble with Hessian on Google App Engine. First I will
describe the setup. I have a persistent class MessageDb declared as
(It contains a String and an arraylist of strings):
@PersistenceCapable
public class MessageDb {
@PrimaryKey
private String user;
@Persistent
private ArrayList<String> words = new ArrayList<String>();
/* getters and setters ...*/
}
I have the following service interface:
public interface IService {
ArrayList<String> testMessage();
/* Some other methods ... */
}
The Service is implemented on App engine in the following way:
public class Service extends HessianServlet implements IService {
private static final PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-optional");
@Override
public ArrayList<String> testMessage() {
PersistenceManager pm = null;
try {
pm = pmfInstance.getPersistenceManager();
MessageDb messageDb;
try {
messageDb = pm.getObjectById(MessageDb.class,
"testMessage");
} catch (JDOObjectNotFoundException e) {
return null;
}
return messageDb.getWords();
//return new ArrayList<String>(messageDb.getWords());
} finally {
if (pm != null)
pm.close();
}
}
}
The service simply retrieves an MessageDb object by key and returns
the object's ArrayList<String>. This code works fine on the local
development server but it fails when deployed on remote Google servers
with the following exception:
java.lang.SecurityException: java.lang.IllegalAccessException:
Reflection is not allowed on private int java.util.ArrayList.size
at
com.google.appengine.runtime.Request.process-0c4ab611241850c6(Request.java)
at java.lang.reflect.Field.setAccessible(Field.java:166)
at
com.caucho.hessian.io.JavaSerializer.introspect(JavaSerializer.java:
122)
at com.caucho.hessian.io.JavaSerializer.<init>(JavaSerializer.java:
81)
at com.caucho.hessian.io.JavaSerializer.create(JavaSerializer.java:
95)
at
com.caucho.hessian.io.SerializerFactory.getDefaultSerializer(SerializerFactory.java:
348)
at
com.caucho.hessian.io.SerializerFactory.loadSerializer(SerializerFactory.java:
278)
at
com.caucho.hessian.io.SerializerFactory.getSerializer(SerializerFactory.java:
224)
at
com.caucho.hessian.io.SerializerFactory.getObjectSerializer(SerializerFactory.java:
197)
at
com.caucho.hessian.io.Hessian2Output.writeObject(Hessian2Output.java:
418)
at
com.caucho.hessian.io.AbstractHessianOutput.writeReply(AbstractHessianOutput.java:
558)
at
com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:
323)
at
com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:
202)
at
com.caucho.hessian.server.HessianServlet.invoke(HessianServlet.java:
389)
at
com.caucho.hessian.server.HessianServlet.service(HessianServlet.java:
369)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
511)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1166)
at
com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:
97)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:
35)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:
43)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:
388)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:
216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:
182)
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:
238)
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
$RequestHandler.headerComplete(HttpConnection.java:923)
at
com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:
76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:
135)
at
com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:
250)
at com.google.apphosting.base.RuntimePb$EvaluationRuntime
$6.handleBlockingRequest(RuntimePb.java:5838)
at com.google.apphosting.base.RuntimePb$EvaluationRuntime
$6.handleBlockingRequest(RuntimePb.java:5836)
at
com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:
24)
at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:
398)
at com.google.net.rpc.impl.Server$2.run(Server.java:852)
at
com.google.tracing.LocalTraceSpanRunnable.run(LocalTraceSpanRunnable.java:
56)
at
com.google.tracing.LocalTraceSpanBuilder.internalContinueSpan(LocalTraceSpanBuilder.java:
576)
at com.google.net.rpc.impl.Server.startRpc(Server.java:807)
at com.google.net.rpc.impl.Server.processRequest(Server.java:369)
at
com.google.net.rpc.impl.ServerConnection.messageReceived(ServerConnection.java:
442)
at
com.google.net.rpc.impl.RpcConnection.parseMessages(RpcConnection.java:
319)
at
com.google.net.rpc.impl.RpcConnection.dataReceived(RpcConnection.java:
290)
at com.google.net.async.Connection.handleReadEvent(Connection.java:
474)
at
com.google.net.async.EventDispatcher.processNetworkEvents(EventDispatcher.java:
831)
at
com.google.net.async.EventDispatcher.internalLoop(EventDispatcher.java:
207)
at com.google.net.async.EventDispatcher.loop(EventDispatcher.java:
103)
at
com.google.net.rpc.RpcService.runUntilServerShutdown(RpcService.java:
251)
at com.google.apphosting.runtime.JavaRuntime
$RpcRunnable.run(JavaRuntime.java:413)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalAccessException: Reflection is not allowed
on private int java.util.ArrayList.size
... 55 more
I am not sure if this security exception is a bug in Hessian (for
using an "forbidden" API) or In App engine (too tight security check)
so I would like to hear what You think about it. I think this is
perhaps connected with the datanucleus enhancements of the persistent
class MessageDb. When the arrayList elements are copied in a new
arrayList (like so: return new
ArrayList<String>(messageDb.getWords()); ) then the exception does not
occur.
Another problem that I ran into is similar but it has to do with
exceptions. I will start with an example. First the exception
declaration:
public class TestException extends RuntimeException {
}
Next the service declaration:
public interface IService {
void testException();
}
And finally the service implementation:
public class Service extends HessianServlet implements IService {
public void testException() {
throw new TestException();
}
}
As You can see this is a trivial implementation to test the exception.
When executed on Google servers it dies like this:
java.lang.SecurityException: java.lang.IllegalAccessException:
Reflection is not allowed on private java.lang.Throwable
java.lang.Throwable.cause
at
com.google.appengine.runtime.Request.process-9880ff155b30e983(Request.java)
at java.lang.reflect.Field.setAccessible(Field.java:166)
at
com.caucho.hessian.io.JavaSerializer.introspect(JavaSerializer.java:
122)
at com.caucho.hessian.io.JavaSerializer.<init>(JavaSerializer.java:
81)
at
com.caucho.hessian.io.ThrowableSerializer.<init>(ThrowableSerializer.java:
59)
at
com.caucho.hessian.io.SerializerFactory.loadSerializer(SerializerFactory.java:
301)
at
com.caucho.hessian.io.SerializerFactory.getSerializer(SerializerFactory.java:
224)
at
com.caucho.hessian.io.SerializerFactory.getObjectSerializer(SerializerFactory.java:
197)
at
com.caucho.hessian.io.Hessian2Output.writeObject(Hessian2Output.java:
418)
at
com.caucho.hessian.io.Hessian2Output.writeFault(Hessian2Output.java:
400)
at
com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:
314)
at
com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:
202)
at
com.caucho.hessian.server.HessianServlet.invoke(HessianServlet.java:
389)
at
com.caucho.hessian.server.HessianServlet.service(HessianServlet.java:
369)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
511)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1166)
at
com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:
97)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:
35)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:
43)
at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:
388)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:
216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:
182)
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:
238)
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
$RequestHandler.headerComplete(HttpConnection.java:923)
at
com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:
76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:
135)
at
com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:
250)
at com.google.apphosting.base.RuntimePb$EvaluationRuntime
$6.handleBlockingRequest(RuntimePb.java:5838)
at com.google.apphosting.base.RuntimePb$EvaluationRuntime
$6.handleBlockingRequest(RuntimePb.java:5836)
at
com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:
24)
at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:
398)
at com.google.net.rpc.impl.Server$2.run(Server.java:852)
at
com.google.tracing.LocalTraceSpanRunnable.run(LocalTraceSpanRunnable.java:
56)
at
com.google.tracing.LocalTraceSpanBuilder.internalContinueSpan(LocalTraceSpanBuilder.java:
576)
at com.google.net.rpc.impl.Server.startRpc(Server.java:807)
at com.google.net.rpc.impl.Server.processRequest(Server.java:369)
at
com.google.net.rpc.impl.ServerConnection.messageReceived(ServerConnection.java:
442)
at
com.google.net.rpc.impl.RpcConnection.parseMessages(RpcConnection.java:
319)
at
com.google.net.rpc.impl.RpcConnection.dataReceived(RpcConnection.java:
290)
at com.google.net.async.Connection.handleReadEvent(Connection.java:
474)
at
com.google.net.async.EventDispatcher.processNetworkEvents(EventDispatcher.java:
831)
at
com.google.net.async.EventDispatcher.internalLoop(EventDispatcher.java:
207)
at com.google.net.async.EventDispatcher.loop(EventDispatcher.java:
103)
at
com.google.net.rpc.RpcService.runUntilServerShutdown(RpcService.java:
251)
at com.google.apphosting.runtime.JavaRuntime
$RpcRunnable.run(JavaRuntime.java:413)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalAccessException: Reflection is not allowed
on private java.lang.Throwable java.lang.Throwable.cause
... 54 more
On the client I get something like this:
java.lang.reflect.UndeclaredThrowableException
at $Proxy0.testException(Unknown Source)
at com.noveideje.testHessian.client.Main.main(Main.java:37)
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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:
110)
Caused by: java.io.EOFException: readObject: unexpected end of file
at
com.caucho.hessian.io.Hessian2Input.readObject(Hessian2Input.java:
2133)
at
com.caucho.hessian.io.MapDeserializer.readMap(MapDeserializer.java:
114)
at
com.caucho.hessian.io.Hessian2Input.readObject(Hessian2Input.java:
1653)
at
com.caucho.hessian.io.Hessian2Input.readReply(Hessian2Input.java:348)
at com.caucho.hessian.client.HessianProxy.invoke(HessianProxy.java:
194)
... 7 more
The ArrayList case also ends in an java.io.EOFException on the client.
Tell me what do You think about this issue. If you have any additional
questions do not hesitate to ask. Thank you for your time.
P.S. The following link contains a test project which contains the
code needed to reproduce the errors. The project uses GAE 1.3.2 and
Hessian 4.0.6
https://docs.google.com/leaf?id=0BzRGFZP1yPUwMzFmNjZiM2YtMzExYi00NDdiLWJlMDgtMmJkMDJiMDhkN2Yx&hl=en
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