Abstract
Geospatial Web services comply with well-established standards to support seamless integration into applications ranging from commercial Geographic Information Systems (GIS) to open source web mapping clients. Descriptions of service capabilities contain information about the provided data. Updates to the underlying database result in changing descriptions. To ensure compatibility with existing solutions, semantic enablement of Geospatial Web services has to reflect both, standards and changing metadata. Semantic annotations link between legacy non-semantic Web service descriptions and their semantic counterparts. The open source Semantic Annotations Proxy (SAPR) is a light-weight RESTful API deployed as free service which “injects” semantic annotations into existing Web service descriptions without breaking the standards. This approach decouples the annotations from the original metadata, which ensures the separation of concerns between data providers and end users with different and sometimes conflicting views on annotations. In addition, the service is robust regarding changes of the service descriptions. The presented approach is focusing on W3C- and OGC-compliant Web services, but can be theoretically applied on any kind of information source with structured metadata.