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Modelling a choreography as a composition of partial descriptions

  • Speaker: Ashley McNeile
  • Date: Tuesday, 3 May 2011 from 00:00 to 17:45
  • Location: Room 745, Malet Street

Multiparty e-commerce collaborations and cross-organizational workflow applications are increasingly attractive given the universal connectivity provided by the Internet. Such applications are inherently concurrent and non-deterministic and, as always with such applications, ensuring that implemented designs will behave correctly under all circumstances is a significant challenge.

The emerging technique for designing extended collaborations is to use a "choreography": a global description of the possible sequencing of message exchange between the participants. The idea is that, once a choreography has been designed, designs for the individual participants can be extracted from it - a technique called "projection". If the participants then interact, each according to its own projected behaviour, the emergent behaviour of the collaboration as a whole should exactly follow the original choreography. If this works successfully the choreography is said to be "realizable". The key question which research into choreography seeks to answer is this: What conditions does a choreography need to obey in order to guarantee that it is realizable? In general, determining realizability of a choreography is a non-trivial question, particularly when the collaboration uses asynchronous messaging and it is possible for different participants to send messages simultaneously.

I will describe my work in this area, which centres on the idea of modelling a choreography as a composition of partial descriptions using ideas from Process Algebra. This has potential to simplify realizability analysis, as it turns out that composition preserves realizability.

This talk does not assume any prior knowledge of choreography techniques or Process Algebras.