- From: Howard N Smith <howard.smith@ontology.org>
- Date: Mon, 17 Nov 2003 21:18:23 +0000
- To: Andrew Berry <andyb@whyanbeel.net>
- Cc: public-ws-chor@w3.org, W.M.P.v.d.Aalst@tm.tue.nl
Hello, I don't think we have spoken before. At 08:57 PM 11/17/2003 +1000, Andrew Berry wrote: >>You have a fundamental problem with the choice of Pi Calculus: there is no concept of locality or partial state. In choreography and web services in general, you can guarantee >that participants (processes) are physically distributed and need to make choices based on a partial view of state. To successfully model, program and reason about these >processes, you need to be able to identify and reason about partial states. Highlighting the Pi Calculus was deliberate, in order to clarify the difference in foundations between BPMS (as defined by BPMI.org) and classical WFMS. Wrt to the issues of locality or partial state, those are inherent to BPML. BPML was inspired by the Pi calculus, but is not limited by it. >>Consider your deferred choice semantics. If the processes identified as choices are physically distributed, you *cannot* make a choice without synchronisation of processes >because distinct choices can be made in a truly concurrent fashion. That is correct, and that is what BPML/BPMS provides. >>Pi Calculus has no way of identifying this issue, let alone reasoning about it. Explicit synchronisation processes, while solving the problem for a given process, require that the >programmer reason about distribution and locality outside the bounds of the Pi Calculus semantics. I would therefore argue that a worflow and in particular a choreography is not >a Pi Process. There I disagree. It is very possible to model those processes using Pi calculus, and this is made explicit in BPML. If you wish to discuss this in voice, I'd be delighted, where I can share some of our initial experiences with BPMS. I would also encourage a greater analysis of BPMS by theorists such as Wil Aalst as has been done before with WFMS. We took the step to create this paper, and map out the patterns, partly as a confidence for ourselves. Best, Howard >Ciao, > >AndyB > > >On Wednesday, November 12, 2003, at 03:00 AM, Howard N Smith wrote: > >> >>Choreography pioneers, >> >>Following a short conversation with Steve R-T, he agreed for me to send you this paper. >>It is intended as a draft for discussion. >> >>The paper is new information. It shows how, based on BPML, it is possible to model all >>of the advanced workflow patterns identified by workflow theorists, whereas most workflow >>engines only support approx 50% of patterns directly and very few of the advanced patterns. >>In addition, it gives insights into the BPML implementation inherent to a BPMS, and how a >>BPMS is able to support many process models not supported by workflow technology. >>Screenshots from Intalio|n3 BPMS are given as examples. Further, the workflow engine itself can >>be modelled in BPML, as reusable processes for use in end-to-end processes. The paper was >>written to more fully explain the work of BPMI.org and its direction in creating BPMS foundation >>technologies. >> >>Peter Fingar and I have taken great care with this paper, and do hope it adds to the >>understanding of BPML/BPMI/BPMS direction. While the paper cannot present proof of >>these claims, you can consider it a report on the work so far. >> >>The paper can be downloaded from: >> >>http://www.bpm3.com/picalculus/workflow-is-just-a-pi-process.pdf >> >>Regards, >> >>Howard >> >> >>--- >> >>New Book - Business Process Management: The Third Wave >>www.bpm3.com >> >>Howard Smith/CSC/BPMI.org >>cell +44 7711 594 494 (worldwide) >>home office +44 20 8660 1963 --- New Book - Business Process Management: The Third Wave www.bpm3.com Howard Smith/CSC/BPMI.org cell +44 7711 594 494 (operates worldwide, dial UK) office +44 20 8660 1963
Received on Monday, 1 December 2003 04:01:23 UTC