Responsiveness in process calculi

A system guarantees responsive usage of a channel r if a communication along r is guaranteed to eventually take place. Responsiveness is important, for instance, to ensure that any request to a service be eventually replied. We propose two distinct type systems, each of which statically guarantees responsive usage of names in well-typed pi-calculus processes. In the first system, we achieve responsiveness by combining techniques for deadlock and livelock avoidance with linearity and receptiveness. The latter is a guarantee that a name is ready to receive as soon as it is created. These conditions imply relevant limitations on the nesting of actions and on multiple use of names in processes. In the second system, we relax these requirements so as to permit certain forms of nested inputs and multiple outputs. We demonstrate the expressive power of the two systems by showing that primitive recursive functions–in the case of the first system–and Cook and Misra’s service orchestration language orc–in the case of the second system–can be encoded into well-typed processes.