Novel mediator architectures for Grid information systems

Virtualization is one of the key features of the Grid. As data-intensive applications gain on importance, it becomes crucial for the success of the Grid to provide transparent access to distributed/heterogeneous data sources as well. In this paper, we describe our concepts to provide a Virtual Data Source (VDS) - a logically single homogeneous data source - on the Grid. Various data sources like relational/XML databases and comma separated value files can be combined via a Mapping Schema. By allowing to invoke user defined functions during the mediation a flexible way of resolving heterogeneities is provided. To show the feasibility of the developed concepts and elaborate the basis for a dynamic version they have been seamlessly integrated into OGSA-DAI to provide a non-proprietary, centralized and easy to integrate solution.