DHPC Technical Report DHPC-055
Process Networks as a High-Level Notation for Metacomputing
Darren Webb, Andrew Wendelborn, and Kevin Maciunas
Archived: 19 September 1998
Published in Proc. of the Int. Parallel Programming Symposium
(IPPS'99), workshop on Java for Distributed Computing,
Puerto Rico, April 1999.
Abstract
Our work involves the development of a prototype Geographical
Information System (GIS) as an example of the use of process networks
as a well-defined high-level semantic model for the composition of
higher-order functions. Our Java-based implementation of this
prototype is known as PAGIS (Process Architecture network for GIS).
Our process networks consist of a set of
nodes and edges connecting those nodes assembled as a Directed Acyclic
Graph (DAG). In our prototype, nodes represent services and edges
represent the flow of data (in this case sub-processed imagery)
between services. Services are pre-defined operations that can be
performed on imagery, presently selected from the Generic Mapping
Tools (GMT) library. In order to control the start and end-point of
the DAG, we define an input node (the original image) and an output
node (the result image).
To exploit potential parallelism, we extend
our idea of a process network to a distributed process network, where
each service may be processed on different computers. A single server
coordinates computation and computation is performed by any number of
workers. The server and workers together constitute the metacomputer.
The server takes a process network from a client and distributes work
to the workers. Each worker applies for work and decides if it is
capable of performing the work offered. In this way, scheduling is
essentially dynamic, and computation can be performed without client
intervention.
PostScript version (gzip compressed)
PDF version
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