Other Communication Languages

A wide variety of communication languages exist, and they will only be touched on briefly here. While not all of the languages listed below fully meet the two criteria for a communications language mentioned in Section 2, they all have, at least, some characteristics of such a language.

• The Conic distributed programming environment [48] is a Pascal-based language with ports defined in each module, a uni-directional link command, and a broadcast primitive. This is fairly restricted, since it neither captures multiple phases of communication nor allows a way of specifying stream usage information.
• The Prep-P automatic mapping system [6] includes a graph description language GDL, closely tied to their programming language XX. Its capabilities are similar to those of Conic.
• The Assign parallel program generator [53] handles partitioning, mapping and routing for static coarse-grained flowgraphs, similar to those used for Gabriel.
• GARP (graph abstractions for concurrent programming [33]) is a graph-rewriting language representing connections among agents. Communications occur only along graph edges. The language, while elegant, lacks notions of communication phases, runtime streams, and stream usage specifiers.
• Lee and Bier [39] discuss mapping a limited class of dataflow program graphs to a scheduled routing environment. They include support for a synchronization primitive to allow changing phases during execution of the dataflow graph.
• Express [23] and PVM [62] both provide some notion of connections, but they are only set up at runtime, and provide a layer of buffering that reduces performance. Their library primitives provide similar functionality to COP's operators.

There are a wide variety of languages designed primarily to express computation, rather than communication, but that include communication in the language. Such languages are largely outside the realm of related work, since they meet neither of the two criteria for communications languages. Languages in this category include, for example, Linda [14], Split-C [16], and CSP [29].