Yes, with some proper design this can work across distributed systems. The tricky part would be identifying which task a newly arriving message should go to. Ideally, you don't want the message to carry state information, but I think that will be unavoidable. Say the workflow for a particular message goes through tasks A-1, B-2, A-3 and B-4 (where A and B are different servers per your example.) If no state is carried with the message, then when B sees the message, it won't know whether the message should go to task 2 or task 4. I think the only state you need is the target task. (or perhaps the last task completed). If a message arrives with target task = null, as it would at A the first time, that is an indication that workflow has not started yet, so A should process the message at the start of its workflow.
----- Original Message ----- From: "Dmitri Colebatch" <[EMAIL PROTECTED]> To: "Guy Rouillier" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, October 23, 2001 1:25 AM Subject: Re: [JBoss-user] MDB dispatcher pattern - opinions > On Tue, 23 Oct 2001, Guy Rouillier wrote: > > > I think the list of tasks and their order should be done external to both > > the messages themselves and to the individual tasks, i.e., in a config file > > somewhere/somehow. That way tasks can be added, removed or reordered > > without changing anything other than the config file. Makes the individual > > tasks and messages more autonomous and therefore easier to write, and also > > makes the workflow easier to manage. > > so something like the struts workflow > (http://jakarta.apache.org/struts/proposal-workflow.html)? yeah, that > makes sense. what about if you wanted the message to go from one server > to another? for instance, have JBoss instances A & B, A has X and Y on it > and B has Z. Now a message is sent to instance A, which then (from the > config file) creates the list of tasks and sends the message off for the > first task - X@A. So instance A gets the message, does task A, finds the > next task is Y@B and sends it to B... etc.. I know this isn't quite what > you said (I assume what you mean is that the dispatcher will read the list > of tasks and then execute each one in a loop fashion), but the (currently > hypothetical) requirement I have been given (yes, hypothetical && given) > is that the system needs to be able to be distributed. > > thoughts? > > cheers > dim > _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
