A National Software Exchange for the High Performance Computing and Communications Program The National Software Exchange (NSE) is a project funded by NASA that aims to facilitate the development and distribution of software enabling technologies for High Performance Computing and Communications (HPCC). Key components of the project are: distribution via the National Information Infrastructure (NII), a multilevel software classification system, a network-based catalog that will serve as a "road map" to important HPCC enabling technologies, a system for selective promoting of important emerging technologies, a research and development program in advanced network-based software distribution mechanisms, an outreach and technology transition effort and a methodology for measurement of the success of the project. The Center for Research on Parallel Computation, comprising Rice University, Syracuse University (NPAC), the University of Tennessee, Caltech, and the Argonne and Los Alamos National Laboratories, will implement this system over a five-year period, emphasizing early deployment of the simplest mechanisms early in the cycle. The NSE will be a prime example of information-on-demand, making available over the network software products and documentation produced and validated by a national collaboration of leading experts in the field of HPCC. The potential audience for the NSE has three important components: 1. The HPCC application and computer science community. 2. Users of NASA, NSF, DoE and other federal centers. 3. Other users of high performance computers, including the many current and potential industrial users for whom the NSE will be a very valuable resource. Software Distribution via the NII The key to a successful software distribution system will be the establishment of a scalable mechanism for distributing software via the national information infrastructure. Many Internet sites have sizable collections of documents or software. It is both unnecessary and undesirable to require that these collections reside at a single site. We plan to put together a CRPC HPCC Mosaic Home Page that will capture in one place the software from the HPCC effort. We plan to develop a software exchange capability for the HPCC community based on existing network interfaces such as Mosaic. This capability is intended to provide mechanisms for the community to access a number of existing software. The maximal benefit to the community will be achieved by having an architecture for software exchange that is open. This will allow a network repository to grow over time. Initially, we will provide existing software technologies to the HPCC community. This will be done by building on existing components to build a prototype that will serve as a model of how such a system should be put together. This prototype can be in place and operational within a month and will evolve through several stages of experiment, prototype, and operating capability. This prototype for the HPCC National Software Exchange will demonstrate how software can be effectively exchanged and reused. It will be based on the underlying premise (reflecting today's software practices) that successful software modules and software, although they may take advantage of pre-existing components, are written primarily by a single team. Software is re-used either by incorporation as subroutines or by use as a starting point for writing new code. Based on our experience in parallel computation, CRPC will construct a catalog or "road map" to high-performance computing enabling technologies. This will be available via the network and will employ multimedia techniques to support fast navigation. We are proposing a set of related projects that are aimed at improving the technology for building software/information repositories, for indexing and search, for automating the maintenance of downloaded systems and for improving the scalability of existing tools and methods. These research projects will feed technology as it is developed into the NSE on an incremental fashion, therefore maintaining the NSE as a world leading network resource. This work will be conducted jointly by Argonne National Laboratory and University of Tennessee as part of the CRPC managed National HPCC Software Repository.