Andy Cooke’s research while affiliated with Heriot-Watt University and other places

R-GMA (Relational Grid Monitoring Architecture) [1] is a grid monitoring and information system that provides a global view of data distributed across a grid system. R-GMA creates the impression of a single centralised repository of information, but in reality the information can be stored at many different locations on the grid. The Registry and Schema are key components of R-GMA. The Registry matches queries for information to data sources that provide the appropriate information. The Schema defines the tables that can be queried. Without the combined availability of these components, R-GMA ceases to operate as a useful service. This paper presents an overview of R-GMA and describes the Registry replication design and implementation. A replication algorithm for the Schema has also been designed.

R-GMA is a realization of the Grid Monitoring Architecture (GMA) that also exploits the power of the relational data model and the SQL query language. The biggest challenge during the development of R-GMA was to ensure that it could be scaled to operate in a large grid reliably. The system is being used in areas as diverse as resource discovery, job logging and bookkeeping, network monitoring and accounting. A secure, reliable and scalable web services version of R-GMA is being developed within the follow-on European project EGEE. Work continues within GGF to define information services for OGSA on the basis of experience with R-GMA.

Computational Grids are distributed systems that provide access to computational resources in a transparent fashion. Collecting and providing information about the status of the Grid itself is called Grid monitoring. We describe R-GMA (Relational Grid Monitoring Architecture) as a solution to the Grid monitoring problem. It uses a local as view approach to information integration and will be a component of the European Union’s DataGrid. The R-GMA architecture and mechanisms are general and could be used in other areas where there is a need for publishing and querying information in a distributed fashion.

Grids are distributed systems that provide access to com- putational resources in a transparent fashion. Collecting and providing information about the status of the Grid itself is called Grid monitor- ing. 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 oered 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.