COORDINATING 1ST-ORDER MULTIPARTY INTERACTIONS

A first-order multiparty interaction is an abstraction mechanism that defines communication among a set of formal process roles. Actual proc esses participate in a first-order interaction by enroling into roles, and execution of the interaction can proceed when all roles are fille d by distinct processes. As in CSP, enrolement statements can serve as guards in alternative commands. The enrolement guard-scheduling probl em then is to enable the execution of first-order interactions through the judicious scheduling of roles to processes that are currently rea dy to execute enrolement guards. We present a fully distributed and me ssage-efficient algorithm for the enrolement guard-scheduling problem, the first such solution of which we are aware. We also describe sever al extensions of the algorithm, including: generic roles; dynamically changing environments, where processes can be created and destroyed at run time; and nested-enrolement, which allows interactions to be nest ed.