[IEEE Third International Symposium on Parallel and Distributed Computing/Third International Workshop on Algorithms, Models and Tools for Parallel Computing on Heterogeneous Networks - Cork, Ireland (05-07 July 2004)] Third International Symposium on Parallel and Distributed Computing/Third International Workshop on Algorithms, Models and Tools for Parallel Computing on Heterogeneous Networks - The CanonicalProducer: An Instrument Monitoring Component of the Relational Grid Monitoring Architecture (R-GMA)