Hence: a Heterogeneous Network Computing Environment Hence: a Heterogeneous Network Computing Environment Hence: a Heterogeneous Network Computing Environment

Network computing seeks to utilize the aggregate resources of many networked computers to solve a single problem. In so doing it is often possible to obtain supercomputer performance from an inexpensive local area network. The drawback is that network computing is complicated and error prone when done by hand, especially if the computers have diierent operating systems and data formats and are thus heterogeneous. HeNCE (Heterogeneous Network Computing Environment) is an integrated graphical environment for creating and running parallel programs over a heterogeneous collection of computers. It is built on a lower level package called PVM. The HeNCE philosophy of parallel programming is to have the programmer graphically specify the parallelism of a computation and to automate, as much as possible, the tasks of writing, compiling, executing, debugging, and tracing the network computation. Key to HeNCE is a graphical language based on directed graphs that describe the parallelism and data dependencies of an application. Nodes in the graphs represent conventional Fortran or C subroutines and the arcs represent data and control ow. This paper describes the the present state of HeNCE, its capabilities, limitations, and areas of future research.