Our application will use JWS tecnology.
We will use Hibernate and a J2EE architecture, and we would like to keep all Hibernate stuff on the server-side.
We noticed that if we use proxy there is an error while de-serializing the object because on the client side there aren't some Hibernate classes.
At now we should put all these jar in the client too: commons-collections.jar; commons-lang.jar; hibernate2.jar; odmg.jar; cglib.jar; commons-logging.jar
In particular hibernate2.jar is quite big, and I think that most part of it is nou usefull on the client-side.
Is it possible to have a hibernate2-client.jar in the future versions?
Regards
Alessandro Rizzi

In this case you will require a remoting api, for example, CORBA, EJB, Javaspaces, JINI etc. You will not need to have (or should ever have as you have noted) any hibernate installed included with each of the clients.

Sorry but I do not understand what you mean.
If you're saying that I don't need any Hibernate jar, I'm sorry to tell you that it doesn't work ... I get this exception:
9-set-2003 18.50.13 net.sf.hibernate.proxy.CGLIBLazyInitializer getProxy

GRAVE: CGLIB Enhancement failed

net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:254)

at net.sf.cglib.CodeGenerator.defineResource(CodeGenerator.java:216)

at net.sf.cglib.CodeGenerator.<init>(CodeGenerator.java:102)

at net.sf.cglib.EnhancerGenerator.<init>(EnhancerGenerator.java:100)

at net.sf.cglib.Enhancer.enhanceClassHelper(Enhancer.java:224)

at net.sf.cglib.Enhancer.enhanceHelper(Enhancer.java:206)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:162)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:139)

at net.sf.hibernate.proxy.CGLIBLazyInitializer.getProxy(CGLIBLazyInitializer.java:26)

at net.sf.hibernate.proxy.SerializableProxy.readResolve(SerializableProxy.java:36)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:324)

at java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:896)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1645)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1830)

at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1756)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1636)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.readObject(ObjectInputStream.java:322)

at com.evermind.server.rmi.RMIInputStream.readType(RMIInputStream.java:118)

at com.evermind.server.rmi.RMIConnection.handleMethodInvocationResponse(RMIConnection.java:1638)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:532)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:275)

at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:797)

at java.lang.Thread.run(Thread.java:536)

Caused by: net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:236)

... 27 more

Caused by: java.lang.ClassNotFoundException: net.sf.cglib.ReflectUtils

... 28 more

9-set-2003 18.50.13 net.sf.hibernate.proxy.SerializableProxy readResolve

GRAVE: Exception deserializing proxy

net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:254)

at net.sf.cglib.CodeGenerator.defineResource(CodeGenerator.java:216)

at net.sf.cglib.CodeGenerator.<init>(CodeGenerator.java:102)

at net.sf.cglib.EnhancerGenerator.<init>(EnhancerGenerator.java:100)

at net.sf.cglib.Enhancer.enhanceClassHelper(Enhancer.java:224)

at net.sf.cglib.Enhancer.enhanceHelper(Enhancer.java:206)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:162)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:139)

at net.sf.hibernate.proxy.CGLIBLazyInitializer.getProxy(CGLIBLazyInitializer.java:26)

at net.sf.hibernate.proxy.SerializableProxy.readResolve(SerializableProxy.java:36)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:324)

at java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:896)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1645)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1830)

at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1756)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1636)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.readObject(ObjectInputStream.java:322)

at com.evermind.server.rmi.RMIInputStream.readType(RMIInputStream.java:118)

at com.evermind.server.rmi.RMIConnection.handleMethodInvocationResponse(RMIConnection.java:1638)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:532)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:275)

at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:797)

at java.lang.Thread.run(Thread.java:536)

Caused by: net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:236)

... 27 more

Caused by: java.lang.ClassNotFoundException: net.sf.cglib.ReflectUtils

... 28 more

rethrown as net.sf.hibernate.HibernateException: CGLIB Enhancement failed: net.sf.cglib.ReflectUtils

at net.sf.hibernate.proxy.CGLIBLazyInitializer.getProxy(CGLIBLazyInitializer.java:37)

at net.sf.hibernate.proxy.SerializableProxy.readResolve(SerializableProxy.java:36)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:324)

at java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:896)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1645)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1830)

at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1756)

at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1636)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1264)

at java.io.ObjectInputStream.readObject(ObjectInputStream.java:322)

at com.evermind.server.rmi.RMIInputStream.readType(RMIInputStream.java:118)

at com.evermind.server.rmi.RMIConnection.handleMethodInvocationResponse(RMIConnection.java:1638)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:532)

at com.evermind.server.rmi.RMIConnection.run(RMIConnection.java:275)

at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:797)

at java.lang.Thread.run(Thread.java:536)

Caused by: net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:254)

at net.sf.cglib.CodeGenerator.defineResource(CodeGenerator.java:216)

at net.sf.cglib.CodeGenerator.<init>(CodeGenerator.java:102)

at net.sf.cglib.EnhancerGenerator.<init>(EnhancerGenerator.java:100)

at net.sf.cglib.Enhancer.enhanceClassHelper(Enhancer.java:224)

at net.sf.cglib.Enhancer.enhanceHelper(Enhancer.java:206)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:162)

at net.sf.cglib.Enhancer.enhance(Enhancer.java:139)

at net.sf.hibernate.proxy.CGLIBLazyInitializer.getProxy(CGLIBLazyInitializer.java:26)

... 19 more

Caused by: net.sf.cglib.CodeGenerationException: net.sf.cglib.ReflectUtils

at net.sf.cglib.CodeGenerator.defineDependancy(CodeGenerator.java:236)

... 27 more

Caused by: java.lang.ClassNotFoundException: net.sf.cglib.ReflectUtils

... 28 more

Regards
Alessandro Rizzi

There are two architectures I was considering in my reply.
1) Client-Server - Where your JWS Swing client communicated with the database directly thus you will need JWS load all of the hibernate jars onto the client.

2) Multi-tier - Where your JWS Swing client talks to a remote server process (middle-tier) by a remoting API (such as CORBA, EJB etc). Thus the middle tier has the hibernate jars. In this senario only the middle tier requires the hibernate jars.

Now to complicate the issue with option 2 is proxies. This is an issue when you are using the domain model to do duties as the DTO. Proxies (or lazy loading) require the session that loaded the parent (and proxy stub) to be present to operate correctly. If it is serialised to the client then the proxy cannot lazy load the domain object resulting in an exception (as you have shown).

The solution is that you will need to completely load all your required domain objects before they are serialised to the client. Hibernate.initialise() helps with this process.

Steve,

Hibernate lets you serialize the proxies. You just need hibernate2.jar and cglib-asm.jar on the other side. It uses a writeReplace() trick.

Yes, I know I need hibernate2.jar and cglib-asm.jar ... my question was. "Is it possible to have something smaller?"
I don't think I need the whole hibernate2.jar on the client side, so if is broken in 2 (or more) little pieces, I can use on the client side only what I really need.
Regards
Alessandro Rizzi

I've got a question which is very related to this topic. I'm using an RMI-server, which does all the database handling with Hibernate 1.1. The RMI-client is deployed via java webstart. Although I don't seem to have any dependencies on hibernate classes on the RMI-client, I get a classNotFoundException for cirrus.hibernate.collections.Set on the client. So with this architecture, is it necessary to have the Hibernate classes also on the client side of the RMI app (and thus deployed via javaws)?

Hibernate replaces the set behind the scene so it can manage the collection, eg, identify changes for cascading operations. When using a Thick client I personnally prefer DTOs in which case you have no dependency.