[jbpm-dev] [Design of JBoss jBPM] - Re: meeting context

[koen.aers@jboss.com]

"alejandro" wrote : Even if it provides a visual notation and semantics it does not (and should not) define an execution model. Hence BPMN should be an influence and not an objective.
Chapter 10 of the BPMN 2.0 draft specifies in about 15 pages the runtime semantics of BPMN. So the committee is clearly not agreeing with your point of view. ;-)
That being said, the specified semantics are described in natural language and thus very unclear and confusing. The execution semantics of an activity are *very* complicated. It is specified by a state diagram that contains no less than 20 nodes. It remains to be seen if such a complicated model will get a lot of supporters/implementers.

"ronald" wrote : Afaik, but could not find it directly, BPMN is based on structured graphs
This is not completely true. BPMN allows for unstructured or 'free' graphs, multiple branches of sequence flow ending in random end events, etc. However, the earlier mentioned runtime semantics specify that some of these constructions are invalid (but of course this would only appear at runtime) as you can see in the following exerpt:

anonymous wrote : The Inclusive Gateway is activated if at least one incoming sequence flow has at least one Token and for each empty incoming sequence flow, there is no corresponding Token in the graph anywhere upstream of this sequence flow, i.e. there is no path from a Token to this sequence flow unless the path visits a                       dominator or postdominator of a non-empty incoming sequence flow of                      the gateway

Aside from all this, I believe indeed that it would be good to discuss the different concepts as much as possible and see where we can 'borrow' from the spec. I saw that the new Choreography part is entirely optional and that the compliance part is still to be defined (if at all possible). So I am not sure how this is going to look when the spec goes final but I am hopeful that we will be able to comply somehow.

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