Hi,
I have not yet had the opportunity to work with javaspaces, but I've read
about them quite a bit (Javapaces: Principles, Patterns, and Practices is
good). They are based on David Gelernters Linda parallel/distributed
computing architecture, and provide all the declarative distributed
asynchronous structure you could want. Jini is theoretically at least more
high available self healing than an ejb container, thats kind of what its
about: implementations may vary of course. In fact one of the proposals
for clustering/HA for jboss was based on jini, I'm not sure why it wasn't
pursued. As I see it, ejbs are primarily intended to provide an easy to
use component based transaction manager connected to existing resource
managers such as relational databases. It standardizes the transaction
manager functionality, keeps track of various context properties, etc, so
you don't have to. If you don't have an existing resource manager that is
one of your major requirements, jini/javaspaces provides you with a much
more flexible distributed computing framework.
I don't know if there is a sufficiently robust javaspaces implementation
for your requirements.
If you find out more I'd like to hear about it.
thanks
David Jencks
On 2001.05.08 11:20:04 -0400 [EMAIL PROTECTED] wrote:
> Hi David,
>
> > I don't have practical experience with what you are suggesting, but are
> you
> > sure javaspaces/jini is not a more appropriate framework for your
> system?
>
>
> Well, I doubt it. I am currently making my way through the documentation
> of
> messagedriven EJBs, and I m pretty much disappointed they are stateless
> in
> fact - state information - if required - would have to be engineered
> "artificially". The system is pretty much in a "vision" phase.
> I have to clear one thing first : I am not a developer anymore, but I
> was.
>
> I am revising the document I have about messagedriven beans right now,
> and
> will come up with a couple of more concrete questions lateron.
>
> The worry I have with Javaspaces etc., is that it maybe does not provide
> such a robust environment as an EJB server for all that - and this
> application is required to be high-available as hell !!
> JavaSpaces is something completely new to me, are you familiar with it ?
>
> Ciao, Jubin
>
> ----- Original Message -----
> From: "David Jencks" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, May 08, 2001 3:14 PM
> Subject: Re: [JBoss-user] Advice wanted : Messagedriven Design
>
>
> > Hi,
> > I don't have practical experience with what you are suggesting, but are
> you
> > sure javaspaces/jini is not a more appropriate framework for your
> system?
> >
> > thanks
> > david jencks
> >
> > On 2001.05.08 06:46:11 -0400 [EMAIL PROTECTED] wrote:
> > > Hi,
> > >
> > > I have some questions for experienced jBosS or maybe just ejb experts
> > > here, having implemented systems with lots of asynchronous
> messagedriven
> > > components.
> > >
> > > The thing I want to design in here is a network of objects
> communicting
> > > with each other. The concept of message-driven components is just
> > > fantastic.
> > >
> > > I will describe what's going on in my zoo :
> > >
> > > we have lots of objects in there - lets call them beings. These
> beings
> > > communicate with each other, have different interests, and the whole
> > > system is going to serve people in the physical world with different
> > > intentions. However it is clear that the objects in the server have
> one
> > > working field - lets say the food industry.
> > >
> > > The objects in there gather data from different datasources :
> databases,
> > > incoming messages, or even clients connecting to the objects. Paul, a
> > > food deliverer, may have his own EJB in there gathering requests for
> him
> > > and managing them in a way that is most economic for him when he
> drives.
> > > His EJB is autonomous, answers requests from other EJBs and just
> gives
> > > them information, and makes deals for Paul, or even IS Paul, whenever
> he
> > > is logged in into his EJB.
> > >
> > > Well - I know thats quite a sick vision.
> > >
> > > We have lots of objects in there who wont ever be the representation
> of
> a
> > > real-life person. But now come the design issues for this system :
> > >
> > > I decided to design every object in there like "Paul". So everything
> in
> > > there, or almost everything, will be asynchronous.
> > > And every EJB will be able to communicate with nearly every other,
> > > asynchronously.
> > >
> > > Has anyone in here ever put up something similar ?
> > >
> > > Is there a big trade-off in performance ?
> > > (whenever, in a synchronous design, there are several method calls
> > > waiting on one object, the ejb server is surely handling them in a
> queue
> > > also - so there are surely queues in synchronous as in asynchronous
> > > design).
> > >
> > > What should I watch out for ?
> > >
> > > My main worry is the performance of a message-driven design. But the
> > > possibilities are just fantastic.
> > >
> > > So my questions are :
> > > - how would you see the performance issue ?
> > > - if performance is acceptable, do you have any design tips for an
> > > asynchronous design ?
> > > - have you ever implemented and been running such a system with jboss
> ?
> > > - with a large number of messagedriven objects floating around (the
> > > number of objects is larger in the messagedriven design of the
> system,
> > > than in a synchronous design)
> > >
> > > What would you say ?
> > >
> > > Best regards, Jubin
> > >
> > >
> > >
> > >
> > > _______________________________________________
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> > >
> >
> >
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>
>
>
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