A Type System for Flexible Role Assignment in Multiparty Communicating Systems

Communication protocols in distributed systems often specify the roles of the parties involved in the communications, namely for enforcing security policies or task assignment purposes. Ensuring that implementations follow role-based protocol specifications is challenging, especially in scenarios found, e.g., in business processes and web applications, where multiple peers are involved, single peers impersonate several roles, or single roles are carried out by several peers. We present a type-based analysis for statically verifying role-based multi-party interactions, based on a simple π-calculus model and prior work on conversation types. Our main result ensures that well-typed systems follow the role-based protocols prescribed by the types, including systems where roles are flexibly assigned to processes.