I'm not sure about Gemstone or Weblogic; but I'll be working with Oracle8i.
It's EJB implementation seems to have good support for persitance and
transactions. I'll keep you posted.
Todd Kromann
-----Original Message-----
From: A mailing list for Enterprise JavaBeans development
[mailto:[EMAIL PROTECTED]]On Behalf Of Fajeau, Philippe
Sent: Tuesday, July 27, 1999 2:59 PM
To: [EMAIL PROTECTED]
Subject: EJB versus business objects, Transaction boundaries,
granularity, and so on.
Hi,
I am new to EJB, please forgive any silly question. We are evaluating some
EJB compliant application servers, and I am getting familiar with the
technology in the process. Our need is not for a Web server but more for a
middleware layer providing support for transactions, security, remote method
invocation (for a GUI and/or between some of the components of the system),
and so on.
Our application has a fairly complex Domain Object Model, and many classes.
I can't imagine making all these classes EJB. That would be a huge overhead
(code wise and at run-time), and would not make a lot of sense, since most
of the classes do not need to be invoked remotely. However, many classes do
have a need for persistency and/or transaction support (if not as an
initiator, at least as a participant). Let's call BO (Business Objects) the
objects that are not EJB but contain some business logic.
I would like to get clarification on a few points:
+ Are EB that are logically contained or referenced through an EJB (directly
or indirectly) automatically made persistent, the same way EJBs are? Is that
capability dependent on the underlying database (OODBMS or RDBMS), or is it
specified by the EJB framework?
+ Are EB that are invoked by an EJB automatically part of a transaction
initiated by an EJB? What happens upon commit or rollback for these EBs?
+ Does anyboddy know of pointers on how to design a fairly complex object
model with EJBs in a pragmatic fashion (i.e. having something that can be
deployed at the end, addressing the different trade off that need to be
made). Most of the litterature I have read just provide simplistic examples
of how to make an EJB, and do not address the real design of a decent size
distributed application.
+ I would be really interested in any result of evaluations/real world
experiences for the following products: Gemstone/J, WebLogic, Persistence
Power Tier. I am particularly interested in Gemstone/J caching mechansim
(based on their OODB technology), and the issues with it: scalability (can
it be used as the repository or should it only be a cache?), synchronization
with another data source such as an RDBMS, and so on.
Thanks,
Philippe
=======================================================
Philippe Fajeau [EMAIL PROTECTED]
System Architect Tel: (604) 918-4732
Abatis Systems Fax: (604) 294-8830
www.abatis-sys.com
=======================================================
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