I'm experimenting with the @Service POJOs on a new project, and I really like the concept, but I have a few questions about what I've discovered.

I've confirmed that the single instance created allows multiple active simultaneous threads. Therefore if I have any fields, I need to synchronize them.

1) Is it therefore safe to use the synchronized keyword in my @Service POJO methods (in violation of the EJB spec)?

2) If I build a JBoss cluster, is there still just a single instance regardless of the number of machines in the cluster?

3) Do @Service POJOs have the same transaction semantics as stateful session beans? (e.g. can I use an extended persistence context in the same way?)