If so, I'd consider subclassing ObjectOutputStream on the client and overriding readObject to call super to read the object, look it up in your cache, then return the cached object if found - otherwise entering this one into the cache and returning that.

Yup, except I'm implementing the readResolve method. This allows me to replace the object that's being deserialized during deserialization. I've got a simple "Registry" that uses HashMaps to cache data. I was hoping there were some more robust options already out there. If not, what I've got should work.

Thanks,
John