Multiparty Symmetric Sum Types

Lasse Nielsen
(DIKU, University of Copenhagen)
Nobuko Yoshida
(Imperial College London)
Kohei Honda
(Queen Mary, University of London)

This paper introduces a new theory of multiparty session types based on symmetric sum types, by which we can type non-deterministic orchestration choice behaviours. While the original branching type in session types can represent a choice made by a single participant and accepted by others determining how the session proceeds, the symmetric sum type represents a choice made by agreement among all the participants of a session. Such behaviour can be found in many practical systems, including collaborative workflow in healthcare systems for clinical practice guidelines (CPGs). Processes using the symmetric sums can be embedded into the original branching types using conductor processes. We show that this type-driven embedding preserves typability, satisfies semantic soundness and completeness, and meets the encodability criteria adapted to the typed setting. The theory leads to an efficient implementation of a prototypical tool for CPGs which automatically translates the original CPG specifications from a representation called the Process Matrix to symmetric sum types, type checks programs and executes them.

In Sibylle Fröschle and Frank D. Valencia: Proceedings 17th International Workshop on Expressiveness in Concurrency (EXPRESS'10), Paris, France, August 30th, 2010, Electronic Proceedings in Theoretical Computer Science 41, pp. 121–135.
Published: 28th November 2010.

ArXived at: http://dx.doi.org/10.4204/EPTCS.41.9 bibtex PDF

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