Also, speaking of BEA, I like this document Sanjay Dalal wrote a couple years ago that speaks of container frameworks. With aspects you could create as dynamic and adaptable a framework as you desired.
http://pw1.netcom.com/~sanjayd/docs/JavaContainerFramework.pdf >From: "Ted Neward" <[EMAIL PROTECTED]> >Reply-To: "Ted Neward" <[EMAIL PROTECTED]> >To: "John Harby" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> >Subject: Re: Re: [EJB-INT] EJB reference in Java Pet Store(thread >safe???) >Date: Sat, 12 Jan 2002 12:02:00 -0800 > >I saw a LOT of people with interest in complementing J2EE with Aspects, and >I saw a LOT of people with interest in *replacing* J2EE with Aspects. Not >sure which approach (if either) is going to prove to be the "best" way of >doing things, but some very interesting discussions where had all around, >including one I had with an engineer from the core infrastructure team at >WebLogic. > >Security wsa a topic that wasn't discussed heavily because it's one of >those >things that people get *very* sensitive about *very* quickly, and they >really had too many other things they wanted to get to. Still, I can see a >number of places where aspects can very easily (once you understand the >concept of what they're doing) slip into a normal call graph to provide >out-of-band contextual information (they call it the "wormhole effect") to >a >downstream call, which is almost always what a security system wants to do >at some point. > >Ted Neward >{.NET || Java} Course Author & Instructor, DevelopMentor >(http://www.develop.com) >http://www.javageeks.com/tneward > >----- Original Message ----- >From: "John Harby" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Sent: Saturday, January 12, 2002 8:23 AM >Subject: Re: [EJB-INT] EJB reference in Java Pet Store(thread safe???) > > > > OT - Ted, thanks for the info about the Aspect workshop. It was >excellent. > > Do you see anyone interested in integrating it into the J2EE framework? >I > > would love to see this in security authorization especially because > > customers I see always end up growing their own. > > > > > > >From: Ted Neward <[EMAIL PROTECTED]> > > >Reply-To: Ted Neward <[EMAIL PROTECTED]> > > >To: [EMAIL PROTECTED] > > >Subject: Re: EJB reference in Java Pet Store(thread safe???) > > >Date: Sat, 12 Jan 2002 01:42:37 -0800 > > > > > >Section 6.5.6 of EJB 1.1 supports your view: > > > > > >"IF a client-invoked business method is in progress on an instance when > > >another client-invoked call, from the same or different client, arrives >at > > >the same instance, the container must throw the >java.rmi.RemoteException >to > > >the second client." > > > > > >In the EJB 2.0 spec, though (assuming the Aug 14 2001 release is still >the > > >final release), there is a footnote at the bottom of the page after >that > > >exact same sentence (this time in section 7.5.6, p 76) that states that >the > > >container may queue or serialize the calls, implying that the calls >will > > >simply block until the first call completes. Hence my posting. > > > > > >Net result--clients cannot assume anything, and had better synch > > >themselves, > > >which I believe is exactly your point. We've come to violent agreement. >:) > > > > > >Ted Neward > > >{.NET || Java} Course Author & Instructor, DevelopMentor > > >(http://www.develop.com) > > >http://www.javageeks.com/tneward > > > > > >----- Original Message ----- > > >From: "Ian McCallion" <[EMAIL PROTECTED]> > > >To: "Ted Neward" <[EMAIL PROTECTED]> > > >Sent: Friday, January 11, 2002 4:29 AM > > >Subject: Re: [EJB-INT] EJB reference in Java Pet Store(thread safe???) > > > > > > > > > > Ted Neward wrote: > > > > > > > > > > They *could* become a shared resource, however, if the client runs > > >multiple > > > > > threads against the same session bean reference, which is quite >common > > >in > > > > > servlet applications.... > > > > > > > > > > The EJB Spec guarantees that only one method call at a time will >be > > >allowed > > > > > on any Bean, IIRC, so other callers will be blocked on any bean >method > > >until > > > > > the first method completes and returns. > > > > > > > > No. The spec guarantees only one method call at a time will be >allowed, > > >but > > > > containers don't do the synchronisation. So if you don't synchronize > > >access to > > > > EJBs (EJBHomes and EJBObjects) from servlets you'll get exceptions > > >raised > > >when > > > > race conditions occur. This is not necessarily simply a matter of > > >putting > > > > synchronize() blocks around the calls to the EJB for two reasons: > > > > > > > > 1. For very high thruput applications synchronizing calls to EJBHome >may > > >cause a > > > > bottleneck, so get a new copy of the EJBHome object whenever needed. > > > > > > > > 2. When viewing a page containing buttons that invoke your servlet a >web > > >user > > > > can click the buttons multiple times and if this happens your >servlet > > >will > > >get > > > > multiple requests from the user that may be processed in parallel on > > >different > > > > threads. This potentially nasty situation that can cause several > > >problems - not > > > > just the problem of parallel invocations of EJBs, so cast your > > >synchronization > > > > net wide, and carefully choose the object to synchronize on - the > > >EJBObject may > > > > not be appropriate since it may not always exist. > > > > > > > > Ian > > > > > > > > ======================================== > > > > Ian McCallion > > > > Alexis Systems Limited > > > > Romsey, UK > > > > Tel: +44 1794 514883 > > > > Fax: +44 1794 501692 > > > > ======================================== > > > > > > > > > > >=========================================================================== > > >To unsubscribe, send email to [EMAIL PROTECTED] and include in the >body > > >of the message "signoff EJB-INTEREST". For general help, send email to > > >[EMAIL PROTECTED] and include in the body of the message "help". > > > > > > > > > > > > > _________________________________________________________________ > > Chat with friends online, try MSN Messenger: http://messenger.msn.com > > > > >=========================================================================== > > To unsubscribe, send email to [EMAIL PROTECTED] and include in the >body > > of the message "signoff EJB-INTEREST". For general help, send email to > > [EMAIL PROTECTED] and include in the body of the message "help". > > > _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff EJB-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
