Abstract
Grid computing is an emerging and enabling technology allowing organizations to easily share, integrate and manage resources in a distributed environment. Computational Grid allows running millions of jobs in parallel, but the huge amount of generated data has caused another interesting problem: the management (classification, storage, discovery etc.) of distributed data, i.e., a Data Grid specific issue. In the last decade, many efforts concerning the management of data (grid-storage services, metadata services, grid-database access and integration services etc.) identify data management as a real challenge for the next generation petascale grid environments. This work provides an architectural overview of the GRelC DAS, a grid database access service developed in the context of the GRelC Project and currently used for production/tutorial activities both in gLite and Globus based grid environments.
TopBackground
This Section introduces the Grid Database Access Service concept, describing the main existing approaches (front-end and embedded) and then dealing with two case studies: GRelC and OGSA-DAI. We will also highlight the main differences between the two research projects from several points of view: programming language, client support, security, data access and integration services, etc. Finally, we will briefly discuss the convergence issues related to the novel OGF DAIS specifications.
Key Terms in this Chapter
Grid-Database: A collection of one or more databases logically interrelated (distributed over a grid environment) which can also be heterogeneous and contain replica, accessible through a Grid-DBMS front end. It represents an extension and a virtualization of the Database concept in a grid environment.
Combined Authorization: The authorization process performed on the Grid DAS side exploiting both Global and Local Authorizations to provide the maximum level of scalability, flexibility and manageability.
Global Authorization: The authorization process performed on the Grid DAS side exploiting Community Authorization extensions (VO-based) present into the user’s credentials (e.g., proxy).
Local Authorization: The authorization process performed on the Grid DAS side exploiting local policies/roles stored on the Grid-DAS Metadata Catalogue and managed by the Grid DAS administrator.
Logical Data Space: The virtualized space where a Grid-Database is managed by the Grid-DBMS.
Grid-DBMS: A distributed system which automatically, transparently and dynamically manage Data Resources, according to the Grid state, in order to maintain a desired performance level. It must offer an efficient, robust, intelligent, transparent, uniform access to Grid-Databases by means of a Grid Data Access Service (Grid-DAS) interface.
Grid Data Access Service: The Grid-DBMS virtualized access interface to Grid-Databases.