Distributed data flow language for multi-party protocols

Abstract

This paper presents a novel object-oriented approach to modeling the semantics of distributed multi-party protocols such as leader election, distributed locks or reliable multicast, and a programming language that supports it. The approach extends our live distributed objects (LO) model with the new concept of a distributed flow (DF), a stream of events that flow concurrently at multiple locations. DFs correspond to local variables, private fields, and method parameters in Java-like languages; they're means by which one stores and communicates state. Protocol instances correspond to Java objects; they consume and output flows; their internal states are encapsulated as internal flows, and their internal logic is represented as operations on flows. Our language provides a new type of concern separation: the semantic structure of protocols is decoupled from implementation details such as construction and maintenance of overlays, trees, and other structures used for scalability. These can be generated by the compiler or at deployment time. This can be done differently in different parts of the network, to match the local environment.