Formal Choreographic Languages

We introduce a meta-model based on formal languages, dubbed formal choreographic languages, to study message-passing systems. Our main motivation is to establish a framework for the comparison and generalisation of standard constructions and properties from the literature. In particular, we consider notions such as global view, local view, and projections from the former to the latter. The correctness of local views projected from global views is characterised in terms of a closure property. A condition is also devised to guarantee relevant communication properties such as (dead)lock-freedom. Formal choreographic languages capture existing formalisms for message-passing systems; we detail the cases of multiparty session types and choreography automata. Unlike many other models, formal choreographic languages can naturally model systems exhibiting non-regular behaviour.