UnitOfWork/Cache/ClientSession Object Update Problem

Question

I have a test case that does a create, read, update, read. This is done through methods on a stateless session bean with all methods requiring a transaction.
I am using Toplink 9.0.3,JBoss 3.0.7 and JTS. Bascally I have a very simple object.
1. I create the object then call my bean, my bean
calls TopLink and gets a ClientSession from a
ServerSession and then gets a UnitOfWork from the
clientSession. I then register the object as new,
and commit the object, which get's written to the
database. My bean method returns the pk.
BeanInterface.createObject(Object obj) {
UnitOfWork uow = Singleton.getServerSession().getClientSession().getUnitOfWork();
uow.registerNewObject();
uow.commit();
2. I then read the object via my bean, by calling
get ClientSession from ServerSession and calling
readObject on it.
BeanInterface.readObject(Object obj) {
ClientSession session = Singleton.getServerSession().getClientSession();
return Utility.cloneObject(session.readObject(obj)); //Insures I am getting my own copy not a ref.
So far so good.
3. I then modify the object in my client and call
an update method on my bean. This methods does a
SessionServer.getClientSession().getUnitOfWork()
I then register my object as existing, deep
merge it and then commit the unit of work.
BeanInterface.updateObject(Object obj) {
UnitOfWork uow = Singleton.getServerSession().getClientSession().getUnitOfWork();
Object clone = uow.registerExistingObject(obj);
uow.deepMergeClone(obj);
uow.commit();
I check the database and the changes are there.
4. Now the kicker. I read the object again like in
step 2 and I get the original object not changes.
So what is in the cache is the orignal object,
wht is in the database is the modified object.
BeanInterface.readObject(Object obj) {
ClientSession session = Singleton.getServerSession().getClientSession();
return Utility.cloneObject(session.readObject(obj)); //Insures I am getting my own copy not a ref.
At this point I am stumped because the changes are in
the database, but not in the cache and I get no
exceptions.
Any thoughts?
Thanks
Mike H. SR.

Answer 1

Donald,
There are three methods you can use. registerExistingObject(), registerNewObject(), registerObject(). If you know that the object is new then using registerNewObject() is better because it does not do the existence check. If you know that that object exists then using registerExistingObject() saves you the overhead of having TopLink determine whether the object exists or not. registerObject() is really only useful if you do not know whether the object is new or exists. So registNew, registExisting are optimizations. In my case we are using registerNewObject() when a consumer says create the object, and registerExistingObject() when they are doing an update. There is also a store, which uses the registObject(), in this case the consumer does not know whether the object is new or existing.
I have been tracking the register method in my debugger and the problem may be in this method. Basically the registerObject or registerExistingObject is suppose to load the original object from the datbase if it is not in the cache. If it is in the cache is should clone it giving back the reference to the clone. In the end there will be two copies of the object the Clone on the cloned object list and the original on the original object list. The deepMergeClone should update the clone with the latest changes and then commit should be deltaing the clone and the original to determine what goes to the db. So far the is working ok because the data does filter to the database. If I turn caching off there are no problems.
Additional information. I did some testing and watching in the debugger, I know this, if I do a serverSession.getClientSession.readObject() or any select or read on the clientSession I get back the same reference every time, but serverSession.getClientSession().acquireUnitOfWork().readObject() returns a different object reference than the clientSession. This may be by design, also I believe the problem is the descriptor, but I cannot figure out what it is about the descriptor, because this only happens on a few descriptors.
By the way I tried the registerObject prior to posting to no avail and had it worked that would have meant there was a problem with registerExistingObject, because this is an existing object.
Thanks for the input.