Ontology-based discovery and composition of geographic information services

Spatial data infrastructures will greatly benefit from the ability to compose geographic information (GI) services to solve complex problems. Discovering suitable services for data access and geoprocessing are major challenges in this endeavour. Current (keyword-based) approaches to service discovery are inherently restricted by the ambiguities of natural language, which can lead to low precision and/or recall. To alleviate these problems, we propose two ontology-based approaches for enhanced discovery of GI services. The approach for ontology-based discovery of data access services is based on semantic matchmaking between Description Logic (DL) concepts representing geographic feature types and the requester’s query. DL subsumption reasoning is used to find matches between queries and service descriptions. The approach for ontology-based discovery of geoprocessing services rests on two ideas. Ontologies describing geospatial operations are used to create descriptions of user requirements and service capabilities. Matches between these descriptions are identified based on function subtyping. In both approaches, service descriptions are based on a shared vocabulary that contains the basic terms of a domain and for which a shared understanding between the actors in the domain is assumed. We use a running example from the geospatial domain to analyse which problems can occur in existing keywordand ontology-based approaches and how the discovery of GI services differs from other service discovery tasks. The example is also used for illustrating the prototypical implementation of the proposed approach. Overview. The thesis consists of eleven papers that address the question how to enhance the discovery of geographic data and geographic information services in spatial data infrastructures by means of ontologies. The collected papers have been published or accepted for publication in peer-reviewed journals or conference proceedings. Chapter I provides a synopsis of the thesis, which puts the papers into perspective and links the topics addressed in each of the papers to each other. The selected papers are included in the thesis by permission of the publishers. They have been written as part of and have partly been co-authored by colleagues from the meanInGs project and the MUSIL research group. Their text appears unchanged, but in cases where subsequent improvements have been made, these are pointed out in the synopsis. The first two papers describe the general setting and the problems addressed in the thesis: • Chapter II: Bernard, L. , Einspanier, U. , Lutz, M. & Portele, C. (2003): Interoperability in GI Service Chains – The Way Forward, in: Gould, M. , Laurini, R. & Coulondre, S. (Eds.): 6th AGILE Conference on Geographic Information Science: 179–187. • Chapter III: Lutz, M. , Riedemann, C. & Probst, F. (2003): A Classification Framework for Approaches to Achieving Semantic Interoperability Between GI Web Services, in: Kuhn, W. , M. F. Worboys & S. Timpf (Eds.): Conference on Spatial Information Theory: Foundations of Geographic Information Science (COSIT 2003). LNCS 2825: 200–217. 1 see http://www.meanings. de/ 2 see http://musil.uni-muenster.de/ 3 In the case of the two papers that have not yet been published (chapters VI and VIII), we reprint the text of the revised version of the manuscript. In chapters IV to VIII, methods for dealing with these problems are developed. • Chapter IV: Klien, E. , Lutz, M. , & Kuhn, W. (2005): Ontology-based Discovery of Geographic Information Services – An Application in Disaster Management. Computers, Environment and Urban Systems (CEUS) (in press). • Chapter V: Klien, E. , Einspanier, U. , Lutz, M. , & H ̈ubner, S. (2004): An Architecture for Ontologybased Discovery and Retrieval of Geographic Information, in: Toppen, F. & Prastacos, P. (Eds.): 7th Conference on Geographic Information Science (AGILE 2004): 179-188. • Chapter VI: Lutz, M. & Klien, E. (2006): Ontology-based Retrieval of Geographic Information, International Journal of Geographical Information Science (in press). • Chapter VII: Lutz, M. (2004): Non-taxonomic Relations in Semantic Service Discovery and Composition, in: Maurer, F. & Ruhe, G. (Eds.): Proceedings of the First ”Ontology in Action” Workshop, in conjunction with the Sixteenth International Conference on Software Engineering & Knowledge Engineering (SEKE’2004): 482–485. • Chapter VIII: Lutz, M. (2005): Ontology-based Descriptions for Semantic Discovery and Composition of Geoprocessing Services. Geoinformatica (accepted for publication). Architecture and implementation issues are described in chapter IX (and partly also in chapters V to VII). • Chapter IX: Lutz, M. (2005): Ontology-based Service Discovery in Spatial Data Infrastructures, in: Jones, C. & Purves, R. (Eds.): GIR’05. Proceedings of the ACM Workshop on Geographic Information Retrieval, Bremen, Germany: 45–54. The last three papers (chapters X to XII) focus on issues related, but not central to the main topics of the thesis. • Chapter X: Schade, S. , Sahlmann, A. , Lutz, M. , Probst, F. & Kuhn, W. (2004): Comparing Approaches for Semantic Service Description and Matchmaking, in: Meersman, R. & Tari, Z. (Eds.): On the Move to Meaningful Internet Systems 2004: CoopIS, DOA, and ODBASE, OTM Confederated International Conferences, Part II: 1062-1079. • Chapter XI: Probst, F. & Lutz, M. (2004): Giving Meaning to GI Web Service Descriptions, in: Bevinakoppa, S. & Hu, J. (Eds.): Web Services: Modeling, Architecture and Infrastructure – Proceedings of the Second International Workshop on Web Services: Modeling, Architecture and Infrastructure, WSMAI 2004, in conjunction with ICEIS 2004: 23–35. • Chapter XII: Klien, E. & Lutz, M. (2005): The Role of Spatial Relations for Automating the Semantic Annotation of Geodata, in: Cohn, A.G. & Mark, D.M. (Eds.): Spatial Information Theory. International Conference (COSIT 2005): 133–148.