ASPfun : A typed functional active object calculus

This paper provides a sound foundation for autonomous objects communicating by remote method invocations and futures. As a distributed extension of ςς-calculus we define ASPfun, a calculus of functional objects, behaving autonomously and communicating by a request-reply mechanism: requests are method calls handled asynchronously and futures represent awaited results for requests. This results in an object language enabling a concise representation of a set of active objects interacting by asynchronous method invocations. This paper first presents the ASPfun calculus and its semantics. Then, we provide a type system for ASPfun which guarantees the “progress” property. Most importantly, ASPfun has been formalised; its properties have been formalised and proved using the Isabelle theorem prover and we consider this as an important step in the formalization of distributed languages. This work was also an opportunity to study different binder representations and experiment with two of them in the Isabelle/HOL theorem prover.

Research highlights
► A functional active object calculus with futures and its properties with examples.
► A type system for active object languages.
► A type-safe calculus featuring active objects and futures, where typing ensures progress.
► A formalisation in theorem prover for further investigations of active objects paradigms.
► A comparison of binder representations using two different ones on our formalisation.