Enhancing interoperability between web-enabled coastal atlases using an ontology-based metadata mediation approach

In recent years significant advances have been made in the development of Internet resources for decision makers, scientists, resource managers and the general public who are interested in coasts around the world. A key element has been coastal web atlases (CWA), based on web-enabled geographic information systems (GIS). Those who have collaborated on CWA developments over recent years have now come together as part of the International Coastal Atlas Network (ICAN). The long-term strategic goal of ICAN is to encourage and help facilitate the development of digital atlases of the global coast based on the principle of distributed, high-quality data and information. Integration of disparate CWAs will help optimize decision making at a variety of levels and across themes. The goal for CWAs integration is to allow efficient data search across heterogeneous distributed CWAs and to provide users with accurate responses to their requests. While trying to integrate CWAs, one must take into consideration the semantic heterogeneity problem. Not only do CWAs use different metadata structures and models, but also different terminologies (ontologies). The terminology used to describe similar data can vary between specialties or regions, which can further complicate data searches and integration. Use of the word "seabed" in Europe versus use of the word "seafloor" to describe the same feature in North America is a good example of this scenario, as is the interchangeable use of "coastline" versus "shoreline" in both regions. Different languages (e.g., English, French) add further complications. From both a human and computational standpoint, users need assurance that the concepts, terminology, even the abbreviations that are shared between two or more individuals, systems, or organizations are understood by all to mean the same thing. In this way the quality of data retrieval and subsequent data integration are greatly increased, as they are based on meaning rather than on mere keywords. This paper describes the development and usage of an ontology-based mediator for catalogue services. Such a mediator will help improve the quality of data searches by ensuring that terms from different ontologies are well translated before performing searches in the local catalogues. Implementation of such a mediator is a necessary first step in achieving the ICAN goal of distributed, but interoperable, CWAs.