Current cache
I wrote a client side cache mechanism using JMS and XML six months ago. I'm running into limitations where I find myself recreating a data object framework on the client side to mimic ejb features such as primary keys and relationships.

Here's a brief overview:

1. Initial Data Object tree is sent to the client by calling a SessionBean method.

2. The client subsribes to a JMS topic and gets data updates in the form: (order has a one-to-many relationship to detail)
[pre]
<order pk=123>
rocket

<detail pk=345>
junk
20021223

<detail pk=346>
love
20021223



[/pre]

3. The client parses the xml and updates it's copy of the data objects.

The cache is not invalidated, it is updated so that the client never has to wait for an update from the server to display data. The data on the client side is always considered to be up-to-date. JMS message are built and sent by a Server-side Interceptor which catches calls to "set" methods.

The problem as I mentioned earlier is that the system is based on data objects.

Dream cache
What I would prefer, is a cache mecanism based on Remote EntityBeans instead of DataObject. The Remote EntityBean would be set up with Client side interceptors that would return values without going to the server.
The cache would also be updated by JMS messages or JavaGroups.

My questions are:
Does a cache system like this already exist?
If not what building blocks should I use to build it?

Philippe