Coastal Atlas Interoperability

Introduction

Advances achieved in Web mapping technologies are allowing a much wider audience to develop and use Web geographic information systems and, in particular, coastal web atlases (CWAs), which were discussed in Chapter 1. While multiple benefits are derived from these tailor-made atlases (e.g., speedy access to multiple sources of coastal data and information, economic use of time by avoiding individual contact with different data holders), the potential exists to derive added value from the interoperability of disparate CWAs, to optimize decision-making at a variety of levels and across themes.

Within the context of coastal Web atlases, interoperability can be briefly defined as the ability of several autonomous, heterogeneous and distributed CSWs to communicate and exchange resources (information, metadata, data or maps) or be used together despite their differences. In a wider context, interoperability has been defined in ISO 2382-1 (ISO/IEC, 1993) as the “capability to communicate, execute programs, or transfer data among various functional units in a manner that requires the user to have little or no knowledge of the unique characteristics of those units.”

Interoperability of coastal web atlases will help to unify the discovery and access of information to users (e.g., scientist, coastal resource managers) and categorize results using a convenient vocabulary. Data discovery relies on documentation provided as part of metadata (notably discovery metadata), such as the dataset title, abstract, extent, keywords, etc. In the context of distributed resources, this information is present in different heterogeneous formats, and systems, according to several existing metadata models and standards. While various efforts exist to provide a unified common form to harmonize different standards (see section 4.3), problems still arise with metadata semantics.

Metadata terms may be agreed upon within an organization or a region, but not necessarily between or among other organizations or regions. 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. From both human and computational standpoints, 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.

Several communities including the database, artificial intelligence and geosciences communities have studied interoperability methodologies in the past two decades. These include database integration (e.g., Yétongnon et al., 2006) and mediation (e.g., Wiederhold, 1992) approaches. Several mediation systems and prototypes have also been developed: examples of such systems are TSIMMIS (Garcia-Molina et al., 1997), PICSEL (Goasdoue et al., 2000), Information Manifold (Kirk et al., 1995), and AGORA (Manolescu et al., 2001).

This chapter discusses standards and tools, defines and proposes solutions on the use of controlled vocabularies and ontologies, and provides an overview of the International Coastal Atlas Network (ICAN) prototype. The solution proposed here is based on ontology mediation and on information that is shared via web services.