in short, you use stateful SB's to maintain client state. This is required for conversation context use cases (multiple screen navigation).
stateless SB's are usually providing a service for any client (e.g. run somebody's credit).
If you want to use instance variables, you must use a stateful SB.
read the Seam doc in your seam download.
thanks for reply
i just wanna tell u that im using DataModel and DataModelSelection and some Out Variable,
is that mean i must use statfull SB
does that statfull SB expires when the session ends unders session scope