• Ontologies aim to enable agreement on the meaning of specific vocabulary terms and so facilitate information integration across applications.
• Ontologies are formalized in logic-based representation languages. Their semantics are thus specified unambiguously.
• Ontology representation languages come with executable calculi enabling querying and reasoning.
(1) permission(u,r) <- User(u) and Resource(r) and AccessRight(ar) and grantedForUser(ar,u) and definedOnResource(ar,r).
(2) permission(u1,r2) <- permission(u1,r1) and executes(r1,i) and Invocation(i) and accesses(i,r2) and Resource(r2) and associatedWith(i,ct) and RequestContext(ct) and contextUser(ct,u2) and permission(u2,r2).
(3) invokesWebServiceWithPolicy(x,y) <- invokes(x,y) and WebService(x) and WebService(y) and describes(sp,y) and ServiceProfile(sp) and profiles(sp,pd) and PolicyDescription(pd).
• application requirements (the number and size of applications, the frequency of changes, the required service level, and so on),
• organizational factors (the number of developers and administrators, their skills, their turnover, the learning curves for using deployment descriptors or for using semantic technology, and so on), and
• service characteristics (the number of Web services, as well as their diversity and complexity).
Daniel Oberle is a senior researcher at SAP Research. He received his PhD from the University of Karlsruhe, Institute AIFB. His thesis discussed applying Semantic Web technologies in middleware solutions—such as application servers and Web services—to facilitate developers' and administrators' daily tasks. He's the author of Semantic Management of Middleware (Springer, 2006). Contact him at SAP Research, CEC Karlsruhe, SAP AG, Vincenz-Priessnitz-Str. 1, 76131 Karlsruhe, Germany; email@example.com; www.aifb.uni-karlsruhe.de/WBS/dob.
Steffen Staab is a professor of databases and information systems in the University of Koblenz-Landau's Institute for Computer Science. He heads the research group on information systems and the Semantic Web (ISWeb). His research interests include the Semantic Web, text mining, ontologies, peer-to-peer computing, and service management with semantic descriptions. He coedited The Handbook on Ontologies (Springer, 2004). He is a member of German Informatics Association (GI e.V.) and the German society for knowledge management. Contact him at University of Koblenz-Landau, 56016 Koblenz, Germany; firstname.lastname@example.org; http://isweb.uni-koblenz.de.
Andreas Eberhart is a software architect for virtualization and grid technologies at HP Germany. Before joining HP, he worked for Informix Software, the International University in Germany, and the University of Karlsruhe, where he led several Semantic Web research projects. Contact him at Essentials Software Organization, Hewlett-Packard GmbH, Altrottstr. 31, D-69190 Walldorf; email@example.com.