HSWG Portrayal Encoding Engineering Reports | OGC

38 Copyright © 2015 Open Geospatial Consortium. 11 Semantic Mediation

11.1 Introduction

Semantic Mediation was addressed to some extent in OWS-8, OWS-9 and OWS-10 see section 2 for references. These Testbeds were mostly focused on performing semantic mediation for taxonomies. For example, gazetteers such as GNIS, GNS, Geonames often use different taxonomies for classifying feature types. To support semantic mediation, mappings are required from one concept in a source taxonomy to another one in the target taxonomy using SKOS mapping relationships such as skos:exactMatch, skos:broadMatch, skos:closeMatch. The semantic mediation has been demonstrated using Web Feature Service-Gazetteer WFS-G, however the mediation is performed as black box on syntactic representation of the features using GML. Some extensions to the OGC Filter standard were added to accommodate the mediation of taxonomies. In OWS-10, the hydrology sub-thread of CCI attempted to address a more general approach for mediation by defining some mapping between two different hydrologic models. However, the solution was based on some UML tools that perform the mapping and no formal model was defined to encode the semantic mapping. To address the semantic mediation of symbology in this testbed, we decided to address semantic mediation for linked data representation of information. We define semantic mediation as the transformation from one conceptual model to another, in particular from one ontology to another. Instances of the target classes are created from the values of instances of the source classes. We also wanted to formally addressthe semantic mediation for taxonomies by providing extensions to SPARQL to perform the semantic mapping. One of the goals of the semantic mediation approach is to provide an extensible, sharable encoding of the semantic mappings that can be processed by machine. For this purpose, we leverage the existing linked data standards RDF, OWL, SPARQL to represent semantic mappings. These semantic mappings can be managed by a semantic mediation service to perform transformation between two models. For this testbed, we demonstrated a RESTful Semantic Mediation Service that performed semantic mapping between the HSWG Incident Model to the EMS Incident Model.

11.2 Review of existing approaches

This section provides an overview of the current existing approaches that attempt to address semantic mediation. A similar review was done in the OWS-8 ER. More up-to- date information is provided here.