In the Hibernate Annotation reference doc all of the classes implement serializable. Everything seems to work fine without it, so is there any need for it?

Thanks
Jason

BTW
By "all of the classes" I am talking about the persisted domain objects.

I don't think Hibernate doesn't need the objects to be serializable (with the possible exception of any composite-id mapping objects).

That said, a lot of people need to make their domain model classes Serializable because they use it for lots of other stuff.

Lots of things you can do with the domain model will force you to need to make them serializable:
- marshalling them across a network connection using ordinary java serialization (i.e. using them as params to EJB calls, or other kinds of RPC mechanism).
- chucking them in a HTTP session: a lot of the app servers (possibly the standard, dunno) require the objects you stick in the session to be serializable