A unified framework for periodic, on-demand, and user-specified software information

Although grid computing can increase the number of resources available to a user, not all resources on the grid may have a software environment suitable for running a given application. To provide users with the necessary assistance for selecting resources with compatible software environments and/or for automatically establishing such environments, an accurate source of information about the software installed across the grid is needed. Existing software information services and general-purpose information frameworks are inadequate for this task. This paper presents a new OGSI-compliant software information service that has been implemented as part of NASA´s Information Power Grid project. This service is built on top of a general framework for reconciling information from periodic, on-demand, and user-specified sources. Information is retrieved using standard XPath queries over a single unified namespace independent of the information´s source. Two consumers of the provided software information, the IPG Resource Broker and the IPG Naturalization Service, are briefly described.