Process Calculi Approaches to Adaptation: From Process Passing to Session Communication

This talk overviews several works on the general theme of specifying adaptation requirements within core calculi for concurrency. Here adaptation broadly refers to the dynamic modification of a given communication behavior; this modification is triggered by some exceptional circumstance, not necessarily negative. Our interest in adaptation started from our works on the expressiveness of higher-order process calculi, concurrent variants of the lambda-calculus enhanced with process passing. This led to the development of adaptable process, a basic process calculus in which adaptation arises as a form of higher-order communication. In the first part of the talk, we review main technical highlights for adaptable processes, notably decidability and verification results. More recently, we have studied how adaptation fits in the setting of structured communications, in which concurrent systems follow protocols abstracted by behavioral types. In this context, we consider extensions of the pi-calculus with session communications and adaptable processes. In the second part of the talk, we review two session type systems for these calculi: they ensure communication safety and consistent adaptation steps.