hi jeff,
I think the solution is a combination of the two. The stateless for the
database reference data and the stateful for the client values. Please
remember that a stateless session bean does not mean it cannot keep state,
its just that the state is not for on one client its for all of them. I
think if you moved to the 100% stateful solution proposed you would probably
suffer memory problems or excessive io through passivation of the same data
across clients. So determine what data relates only to the client (stateful)
and what relates to them all (stateless session bean) and you will porbably
meet your performance goals. One question ... how is the rule based engine
implemented (ejb, jni, corba.....) this could lead to some more options.
William
PS: Please remember that advice giving on this newgroup maybe sometimes
reflective of the failings of some vendors offering. The ejb container that
I use does not seem to have problems scaling this is in part to my good
design and their superior implementation of ejb1.1 and corba 2.3. good luck.
> -----Original Message-----
> From: Richard Monson-Haefel [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, February 16, 2000 1:41 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Caching data in an stateful session EJB???
>
> Jeff Davidson wrote:
>
> > We are designing a system based on J2EE and EJB which needs to service
> thousands
> > of client applications. Originally we thought that each client would
> interact
> > with one stateful session EJB in order to collect & cache data pulled
> from
> > corporate databases. However, ass I've been reading more on EJBs, it
> sounds
> > like this may not be a very good approach in terms of scaling and
> > performance. If we use stateless session beans, where can we cache the
> > data retrieved from the database? We need the data for subsequent
> > calls to a rules-based engine to have it process and return information
> > which we then return to the client app. Then, as we collect information
> > from the client app, we need to combine this with the data from the
> > db to be able to make more requests to the rules-based engine. So we
> need
> > to cache it somewhere, but where?
>
> Perhaps you should question your own assumptions about the performance
> penalties of
> using Stateful Session beans, because the scenario you just described
> indicates that
> a stateful session bean is what you need. Why reinvent a cache per client
> -- which
> is what you need -- when stateful session beans provide that already.
>
> -Richard
> --
> Author of Enterprise JavaBeans
> Published by O'Reilly & Associates
>
> EJB FAQ
> http://www.jguru.com/faq/EJB
>
> EJBNow.com
> http://www.ejbnow.com
>
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