A Tool for Distributed Application Development Based on Asynchronous Message Passing

This paper describes a tool for the development of distributed applications. The target execution environment is a network of heterogenous general-purpose workstations. This tool (called HERMES) mainly handles the message transport layer and does not deal with aspects more directly related to parallel computing, such as the topology of communicating processes or load balancing among processors. A coarse-grained concurrence is supported and the resulting parallel architecture is based on the multiple-instructions multiple-data paradigm. This system is mainly characterized by its ability of handling special messages (alarm and urgent) that are guaranteed immediate processing by the receiving process. Messages are always asynchronous, in that they are immediately delivered to destination, without any temporary buffering by the communication system (i.e. asynchronously with respect to the program execution). The system is still under development but a preliminary version, restricted to processes running on the same host, is currently under test