Parallel applications, emerging in the last several years, require high-performance communication and computation systems, and have additionally placed stringent quality of service (QoS) requirements on programming environments. Especially with the introduction of new communication protocols for cluster computing such as Virtual Interface (VI) architecture, the design and implementation of an efficient userlevel messaging layer for parallel applications presents itself as a vital factor for effectively utilizing the underlying system architecture and reducing overhead to achieve QoS. Real-time message passing interface (MPI/RT) is an ongoing standard and is targeted at embedded real-time distributed systems. This paper describes the impact of the design of messaging layer API in achieving better QoS, effective implementation, and utilization of resources. API design, implementation, and performance between two messaging layer standards, MPI/RT and MPI are compared. Some aspects of desi...

We describe a number of early efforts to make use of the Message Passing Interface (MPI) standard in applications, based on an informal survey conducted in May-June, 1994. Rather than a definitive statement of all MPI developmentwork, this paper addresses initial successes, progress, and impressions that application developers have with MPI, according to the responses received. We summarize the important aspects of each survey response, and draw conclusions about the spread of MPI into applications. An understanding of message-passing, and access to the MPI standard are prerequisites for appreciating this paper. Some background material is provided to ease this requirement. Skjellum, et al. Early MPI::: 3 1