A Message Oriented Middleware Library

Abstract

A message oriented middleware inter-process communication library called Nora has been designed, constructed, and validated. The library is written in C++. The middleware is designed to bridge two of the main messaging standards, the Message Passing Interface (MPI) and the Data Distribution Service (DDS), by enabling communications for (1) computationally intensive distributed systems that typically follow a master-slave design and (2) general data distribution. The design is original and does not borrow from either specification. The library can be statically linked to application code so that the library is part of each application in a distributed system. The implementation for master-slave messaging has not yet been completed, but the great majority of the work is done; the general data distribution model has been fully implemented. The design is critically evaluated.A key aspect of the library is configurability. Various characteristics of the messaging library, such as the number of message producer and consumer threads, the message types serviced by each thread, the types of communication mechanisms, and others are specified through a configuration file. Consequently, the library has only to be built once for all applications in a distributed system and communications for each application are tailored through a unique configuration file. The library application programmer interface (API) is structured so that communications details can be isolated from the application code and therefore applications are not affected by changes to the IPC configuration.Beyond its use for the two classifications of problems listed above, it is also suited for use by system architects that are investigating resource requirements and designs for new systems because applications can be reconfigured quickly for different communications behavior on different platforms through the configuration file. Thus, it is useful for prototyping and performance evaluation.