[jboss-dev-forums] [Design of JBoss jBPM] - Re: how crucial are exception handlers ?

[estaub]

Tom,

Sorry, "rigorous" could be taken in so many ways... I should have been more ... um... rigorous  ;-).

I meant that it should be easy for someone to understand where the transaction edges are, without digging into the implementation of each delegation class.  So part of this is a designer UI issue, but the engine has to behave in a way that the designer UI can predict.  Someone modifying the process shouldn't need to exhaustively study the behavior of every component already in the process in order to understand where it will rollback to if an error occurs.  [On the other hand, it's very reasonable to expect someone adding a node to understand its transaction semantics.]

The engine can help with this by providing a means by which nodes (and transitions) can express their transaction behavior.  Clearly there's lots of progress in PVM versus JPDL3.  I'm not sure how much more is needed.  I don't understand PVM very well... is it valid to have an Activity that is not an ExternalActivity, yet waits for an external event?  I hope not - this would mean that the automatic transaction edges caused by wait states are denoted by the class inheritance.  This is the kind of "rigor" I'm hoping for in the engine.  If the designer UI has access to the  activity class, it can introspect and provide visual cues.

anonymous wrote : i don't want to be limited to the bonita behaviour that you describe
I couldn't agree more.  IMHO, this is a key differentiator for JPDL - the ability to efficiently do "microflows".

anonymous wrote : we enhance the command based session facade that sits in front of the jbpm-context-blocks. in such a session facade, you could choose to have it operate synchronously or asynchronously.
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Sorry, I don't follow - I don't know enough about where things have gotten beyond JBPM3.  By "synchronously", do you mean "in the same transaction"?

Thanks,
-Ed Staub

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