Session objects are never shared and are not meant to be persistent
(though they do have an activation/deactivation mechanism in place
for stateful session beans). A SessionBean always serves one client
at a time. Stateless session beans may serve multiple clients but not
simultaneously. A generally accepted architecture is the opposite of
what you describe, namely session beans wrapping entity beans. It's
the entity beans that are shared between multiple clients, not the other
way around.

I have another question that came up recently in our work:
How about non-bean to bean relationships? We're all talking about
bean to non-bean, but what if at the end of some graph of non-bean
objects you want to have a refernce to a entity bean? What are the
implications of that for persistence mapping and transactions?

Frank

-----Original Message-----
From: A mailing list for Enterprise JavaBeans development
[mailto:[EMAIL PROTECTED]]On Behalf Of Javier Deniz
Sent: Thursday, July 29, 1999 9:14 AM
To: [EMAIL PROTECTED]
Subject: Re: Hanlding EB relationships,was RE: fat getter/setters versus
get/ set with all data


Chris Raber wrote:
> - Bean to dependent object. My opinion is that these are always
aggregating
> relationships. If a bean needs to relate to a non-bean object, which is
does
> not "own", then the dependent-object should probably be escalated to bean
> status.

I am not quite sure about that. Consider, for example, a Session object in
the sense described by Yoder/Barcalow in their PLoP'97 paper "Architecture
Patterns for Enabling Application Security" (to appear in PLoPD-4 book).
Their "solution" section starts saying:

      Create a Session object, which holds all of the
      variables that need to be shared by many objects.

Note that we may want persistent session objects which are referenced
by many entity beans to hold shared values during long business scenarios.
Those session objects are typically created once by some kind of
administration utility and then used only by the entity beans that
share the several values hidden in the session object.
Wrapping session beans or clients do not access them in typical
business situations. We think that making them beans adds unnecessary
overhead. We would rather leave the OODBMS handle the access to such
objects here. Adding "EJB access" wouldn't add much value here
(would it?). Using a non-OO DB may be different, though.

Javier Deniz

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