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I don't know much about mathematical theory, but discussion on the value of using Picalculus in BPM is getting attention.

BPEL and Pi-Calculus

Thursday, October 23rd 2008 | Ismael Ghalimi

Apparently, my last article on why BPEL matters ruffled some feathers. My arguments about why BPEL is better than XPDL on purely mathematical grounds are upsetting some “academics”, and I am being portrayed as a shallow marketer for making such unsubstantiated statements. I love nothing more than a fair fight, and I am pleased to see that such discussions are finally making their way online, proving that the issues at hand really matter. So let’s get back on the ring!

I made the claim that BPEL leverages the Pi-Calculus model, and as a result is more suited to support the execution of distributed processes. The “academic” refuting this claim countered that BPEL does not support the “distinguising feature of pi-calculus compared to other members of the process algebra family,” namely channel passing. Well, I beg to differ, and Assaf Arkin, CTO of Intalio, author of the BPML specification, and co-author of the BPEL specification would as well, as can be seen on this article.

My personal credentials with respect to such an “academic” discussion might be in doubt (after all, I’m just a marketing guy), but Assaf Arkin’s cannot, as illustrated on this interview of Robin Milner, inventor of Pi-Calculus.

But let’s cut through the chase. My supposedly-invalid marketing claim are no better than equally invalid pseudo-science. Let’s focus on facts instead, and what the combination of BPMN and BPEL allows, today, in the real world of enterprise software. For this purpose, I asked my friend Jacques-Alexandre Gerber to produce an example of an end-to-end process made of three participants, represented through three separate processes that synchronize each other via message passing.

Such a process can be modeled in BPMN, fully translated into BPEL, and directly executed by a BPEL engine. It shows how BPMN and BPEL can be used to describe and execute distributed processes, leveraging the very elements that make Pi-Calculus so powerful. If your XPDL tool can do that, show it to me. If it cannot, we made our point.

And moving forward, I’d very much appreciate if such discussions could place on the blog where they originated. Like any other human being, I have feelings, and right now I feel pretty lonely. Is my writing so ugly that it is scaring you off?