John Brooke, Donal Fellows, Oscar Corcha
University of Manchester, UK
The problem of interoperability between different Grid middleware systems is becoming acute. There now exist important production Grids running middleware that purports to have the same functionality but it is impossible to demonstrate this by any formal process. As an example the EU Infrastructure has two major projects EGEE and DEISA which run differing middleware (gLite from EGEE, Unicore from DEISA). To address this problem, two recent EU projects, UniGrids and OntoGrid, have collaborated to produced a Grid Resource Ontology which is available on the web at http://www.unigrids.org/ontology.html. This ontology is, to our knowledge, unique since it models not just the resources used on Grids but also the processes by which the resources are used. The ontology has been modularized and therefore is not committed to any particular approach to resource sharing (such as OGSA) but can be specialised to model OGSA and systems which are designed to be implementations of OGSA (e.g. GT4 and Unicore). The modularized ontology also includes the Semantic OGSA architecture S-OGSA developed in the OntoGrid project. The GRO is now being utilized on an experimental basis by Barcelona SuperComputing Centre which hosts the largest supercomputer in Europe (Mare Nostrum) as part of the DEISA Grid. In the position paper we describe the genesis of the approach we have adopted and outline how the GRO could be used to test the possibility of interoperability between Grids using differing middleware.