Forum OpenACS Q&A: Pi-Calculus for Workflow?

Collapse
22: Pi-Calculus for Workflow? (response to 1)
Posted by Andrew Piskorski on
I just stumbled across a mildly interesting article, A Conversation with Steve Ross-Talbot "Merging the Worlds of Academics and Practitioners", ACM Queue vol. 4, no. 2 - March 2006. In it, among other things, Ross-Talbot claims that for practical use the Pi-Calculus (search on lambda-the-ultimate.org) is clearly superior to Petri net theory. Apparently, the Pi-Calculus allows callbacks to change the dependency graph on the fly, while Petri Nets must be static.

He seems to say that from that it follows (he doesn't say why) that the multiple thingees using the Pi-Calculus are composable while multiple Petri Nets are not. If accurate, that's interesting, as composability is a big advantage in practical robustness... (For comparison, mutex locks are not composable but transactions are, which is one of the many advantages of transactions.)

Apparently his startup released and maintains their pi4soa "Pi Calculus for Service Oriented Architectures" toolkit under an Open Source (Apache) license.

Collapse
Posted by Andrew Piskorski on
Hm, I was recently reading about object-capability systems and the like (e.g., Shapiro's Coyotos, Miller's E), and learned of the existence of the "Join Calculus". It is, reportedly, provably equivalent to the Pi Calculus, but perhaps (reputedly?) better for actual implementations, particularly those involving distributed processing (a la Erlang). (I don't actually understand it, though.)