Abstract models and specifications can be used in the design of distributed applications to formally reason about their safety properties. However, the benefits of using formal methods are often negated by the ad hoc process of mapping the semantics of an abstract specification to algorithms designed to be executed on target distributed platforms. The challenge of formally specifying communication channels and correctly implementing them as algorithms that use realistic distributed system services is the focus of this paper. This work provides an original formal specification of an abstract asynchronous communication channel with support for dynamic creation and tear down of links between participating network nodes, and its implementation as an algorithm using Java sockets. The specification and the algorithm are expressed using the Input/Output Automata formalism, and it is proved that the algorithm correctly implements the specification, viz. that any externally observable behavior (trace) of the algorithm has a corresponding behavior of the specification. The approach presented here can be used to implement algorithms for dynamic systems, where communicating nodes may join, leave, and experience delays. The result is also of direct benefit to automated code generation, such as that implemented within the Input/Output Automata Toolkit at MIT.

Abstract models and specifications can be used in the design of distributed applications to formally reason about their safety properties. However, the benefits of using formal methods are offset by the challenging process of mapping the functionality of an abstract specification to the low-level executable code for target distributed platforms. Formal specification and practical implementation of communication channels is one such challenge. This work provides the first formal specification of an abstract asynchronous communication channel with support for dynamic creation and tear down of communication links between participating network nodes, and its implementation using Java sockets and TCP. The specifications are formulated using Input/Output Automata formalism, and it is proved that the resulting implementation preserves the safety properties of the abstract channel. The approach presented here can be used to implement algorithms for dynamic systems, where communicating nodes may join, leave, and experience arbitrary delays, and it can directly benefit automated code generation.