Subtyping and Locality in Distributed Higher Order Processes

This paper studies one important aspect of distributed systems, locality, using a calculus of distributed higher-order processes in which not only basic values or channels, but also parameterised processes are transferred across distinct locations. An integration of the subtyping of λ-calculus and IO-subtyping of the π-calculus offers a tractable tool to control the locality of channel names in the presence of distributed higher order processes. Using a local restriction on channel capabilities together with a subtyping relation, locality is preserved during reductions even if we allow new receptors to be dynamically created by instantiation of arbitrary higher-order values and processes. We also show that our method is applicable to more general constraints, based on local and global channel capabilities.