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Overall Strategy for the NHSE

The effectiveness of the NHSE will depend on discipline-oriented groups and Grand Challenge teams having ownership of the discipline-oriented software repositories. The information and software residing in these repositories will be best maintained and kept up-to-date by the individual disciplines, rather than by centralized administration. Central administration will be use instead to handle interoperation and to meet common needs, such as indexing, searching, etc.

Although the various disciplines will have ownership of the repositories, they should not be expected to develop the software and tools for building, managing, and interfacing to their repositories. Because much information retrieval (IR) software is currently available, both in the form of client and server programs (e.g., http servers and WWW browsers), as much of this software should be incorporated into the NHSE as is useful. Using existing software has the following advantages:

1. It will reduce the amount of software development required for deployment of the NHSE.
2. It will ease interoperation with outside information sources that already use existing IR software.
3. It will take advantage of the familiarity that many users already have with these tools.
4. The NHSE will be able to take advantage of ongoing development efforts and enhancements for these tools without investing additional IR software development efforts of its own.
5. The HPC software and other information collected by the NHSE will be readily accessible by outside organizations such as schools, libraries, and museums.

The scope of the NHSE is software and software-related artifacts produced by and for the HPCC Program. Software-related artifacts include algorithms, specifications, designs, and software documentation. A software package or software-related artifact is also called an asset, defined to be any item of interest stored in a reuse library. The following three types of software are to be made available:

• Systems software and software tools. This category includes parallel processing tools such as parallel compilers, message-passing communication subsystems, and parallel monitors and debuggers.
• Basic building blocks for accomplishing common computational and communication tasks. These building blocks will be of high quality and transportable across platforms. Building blocks are meant to be used by Grand Challenge teams and other researchers in implementing programs to solve computational problems. Use of high-quality transportable components will speed implementation, as well as increase the reliability of computed results.
• Research codes that have been developed to solve difficult computational problems. Many of these codes will have been developed to solve specific problems and thus will not be reusable as is. Rather, they will serve as proofs of concept and as models for developing general-purpose reusable software for solving broader classes of problems. The development of this reusable software is expected to be undertaken by commercial companies, rather than by academic researchers.

Although the different disciplines will maintain their own software repositories, users should not need to access each of these repositories separately. Rather, the NHSE will provide a uniform interface to a virtual HPCC software repository which will be built on top of the distributed set of discipline-oriented repositories, as shown in Figure 1. The interface will assist the user in locating relevant resources and in retrieving these resources. A combined browse/search interface will allow the user to explore the various HPCC areas and become familiar with the available resources. A longer term goal of the NHSE is to provide users with domain-specific expert help in locating and understanding relevant resources.

  
Figure 1: Virtual Repository Architecture

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