A High-Performance Active Digital Library

We describe Javaflow and Paraflow, the client and server parts of a digital library, providing high-performance data-retrieval and data-mining services, with emphasis on user interface as well as computing efficiency. Paraflow is a component model for high-performance computing, implemented as a thin layer on MPI (Message Passing Interface); it controls a heterogeneous metacomputer, allowing groups of processes (services) to work collectively and communicate with each other by parallel messaging links (channels). Javaflow is a straightforward, intuitive, loosely-coupled component model for Java applets, allowing them to be combined into a GUI that can run on a thin client from a standing start. Javaflow controls Paraflow through a well-exposed text interface which is carried by authenticated telnet, while the output of the computation can be web-pages, files, or high-speed graphics. As an example, we discuss the SARA remote-sensing library, which provides public retrieval of multichannel images of the Earth, as well as private, authenticated access to a variety of image-processing services running on parallel supercomputers.