Abstract
Grids are distributed systems that provide access to computational resources in a transparent fashion. Providing information about the status of the Grid itself is called Grid monitoring. As an approach to this problem, we present the Relational Grid Monitoring Architecture (R-GMA), which tackles Grid monitoring as an information integration problem. A novel feature of R-GMA is its support for integrating stream data via a simple " local as view" approach. We describe the infrastructure that R-GMA provides for publishing and querying monitoring data. In this context, we discuss the semantics of continuous queries, provide characterisations of query plans, and present an algorithm for computing such plans. The concepts and mechanisms offered by R-GMA are general and can be applied in other areas where there is a need for publishing and querying information in a distributed fashion