It's a good example, but for this sort of thing a work flow engine might be
more appropriate anyway. If you find yourself hand coding direct graph
execution, you're re-inventing the wheel. Check out www.verveinc.com.
-Chris.
> -----Original Message-----
> From: Laird Nelson [SMTP:[EMAIL PROTECTED]]
> Sent: Monday, February 28, 2000 2:52 PM
> To: [EMAIL PROTECTED]
> Subject: Re: jms & ejb
>
> ----- Original Message -----
> From: Bhattacharyya, Ana <[EMAIL PROTECTED]>
> > or rather when do u need asynchromous calls to a
> > bean. can anyone describe the situation where I may need such things.
> Also
> > which model is best suited for ejb -- the pub/sub model or the P2P
> model??
>
> Think of a workflow where four things need to all happen before the fifth
> one can. It does not matter how things one through four happen, or when
> they happen: it simply matters that they all occur, successfully or
> erroneously. Only then, let's say, can you do your fifth action.
>
> Since you cannot use threads in a session bean, you cannot, for example,
> inside a stateless session bean do actions one through four in parallel.
> You just can't do it. You must do item one followed by item two followed
> by
> item three. If each action could be done in parallel, and each action
> takes
> four days, then you can see that NOT doing them in parallel--i.e. working
> with EJB session beans--results in a terrible architecture.
>
> This is a barn-sized hole in the EJB specification. The way that you are
> supposed to be able to get around this in the 2.0 specification will be
> via
> pub/sub messaging over JMS, where each action to be performed is
> essentially
> the publishing of a message to either another bean or a third-party
> program.
>
> In my mind this only solves some of the problems and completely ignores
> the
> simple multiplexing thread problem I presented earlier.
>
> Cheers,
> Laird
>
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