Oops; didn't make it out the first time. > Subject: Re: Threads question (Concrete examples?) > Date: Thu, 09 Mar 2000 16:42:40 -0500 > From: Laird Nelson <[EMAIL PROTECTED]> > Organization: Perot Systems Corporation (http://www.perotsystems.com) > To: [EMAIL PROTECTED] > CC: [EMAIL PROTECTED] > References: <[EMAIL PROTECTED]@dano> > > Dan OConnor wrote: > > Since JMS seems to be the answer whenever threads are the > > question, advocates for a threading API might want to point out > > specifically where JMS fails to provide the equivalent logical > > operations. > > Suppose I take the example proffered before of a car rental application > (at least I think that's what it was). There was parallel access to > three or four legacy systems involved, if I recall correctly. Suppose I > do this via JMS. In my session bean, I do the following operations: > > publish message 1 (returns immediately) > publish message 2 (returns immediately) > publish message 3 (returns immediately) > block and wait for all return messages from subscribers > > Now suppose that the subscriber to message 1, who is responsible, > out-of-band, for hooking up to legacy system 1, hangs indefinitely or > crashes or at least never publishes back a response to message 1. My > session bean will block in step 4 forever, waiting for the response. > > Contrast this with: > > start thread 1 (returns immediately) > start thread 2 (returns immediately) > start thread 3 (returns immediately) > join() with all threads > > If thread1 throws an exception or cannot proceed, he will exit--he will > exit badly, to be sure, but the join() will still "work" at the end, > i.e. the hypothetical session bean that's doing the join() will not > hang. > > Does that make sense? > > Cheers, > Laird =========================================================================== 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".
