Ch. Bussler et al. (Eds.): WES 2002, LNCS 2512, pp. 175–187, 2002. © Springer-Verlag Berlin Heidelberg 2002 A Service Infrastructure for e-Science: The Case of the ARION * System Catherine Houstis, Spyros Lalis, Vassilis Christophides, Dimitris Plexousakis, Manolis Vavalis, Marios Pitikakis, Kyriakos Kritikos, Antonis Smardas, and Charalampos Gikas Institute of Computer Science, Foundation for Research and Technology – Hellas P.O. BOX 1385, GR-711 10 Heraklion, Greece _LSYWXMWPEPMWGLVMWXSTHTQEZTMXMOEO OVMXMOSWWQEVHEWLEVKMOEWa$MGWJSVXLKV Abstract. The ARION system provides basic e-services of search and retrieval of objects in scientific collections, such as, data sets, simulation models and tools necessary for statistical and/or visualization processing. These collections may represent application software of scientific areas, they reside in geographi- cally disperse organizations and constitute the system content. The user, as part of the retrieval mechanism, may dynamically invoke on-line computations of scientific data sets when the latter are not found into the system. Thus, ARION provides the basic infrastructure for accessing and producing scientific infor- mation in an open, distributed and federated system. More advanced e-services, which depend on the scientific content of the system, can be built upon this in- frastructure, such as decision making and/or policy support using various in- formation brokering techniques. 1 Introduction ARION is a service-based infrastructure designed to support search and retrieval of objects in scientific collections, such as, data sets, simulation models and tools neces- sary for statistical and/or visualization processing. It also actively supports dynamic and distributed scientific data processing workflows, in interactive and batch mode. The computational grid used in ARION is composed of geographically distributed and heterogeneous resources, namely, servers, networks, data stores and workstations with GUI displays, all resident to the member organizations that provide the scientific content and resources. ARION provides the means [1], [2] for organizing this ensem- ble so that its disparate and varied parts are integrated into a coherent whole. Hence, ARION can be viewed as the middleware between users, the data they wish to process and the computational resources required for this processing. Central to ARION are ontologies and workflows. They are the main mechanisms for recording expert knowledge, for information representation/navigation and for expressing computation processes over the grid. * ARION is supported by the European Commission under the 5 th Framework Programme, IST-2000-25289, Key Action 3: Digital Heritage and Cultural Content.