A type system for client progress in a service-oriented calculus

We introduce a type system providing a guarantee of client progress for a fragment of CaSPiS, a recently proposed process calculus for service-oriented applications. The interplay of sessioning and data-orchestration primitives makes the design of a type system for CaSPiS challenging. Our main result states that in a well-typed CaSPiS system, and in absence of divergence, any client invoking a service is guaranteed not to get stuck during the execution of a conversation protocol because of inadequate service communication capabilities.