New OGC standard has an important role in improving shared situational awareness.

Contributed by: 
Roger Brackin, MSc, Envitia Research Director

A new standard being developed in the OGC has an important part in improving shared situational awareness. The candidate OGC Web Services (OWS) Context standard encodes the key elements of a common operating picture: the geographic area, an optional time range, and an ordered series of layers from different services or inline content. This allows a situational awareness view of one user to be passed to other users so that the same picture can be reconstructed. The context standard also allows catalogue queries and results from multiple catalogues, and web processing requests and results to be passed around easily.

The important idea here is that the context document can pass references to the services that provide the layers. The layers can be provided by services that implement OGC Web Map Service (WMS), Web Map Tiling Service (WMTS), Web Feature Service (WFS), Web Coverage Service (WCS), Web Processing Service (WPS) and Catalog Service –Web (CSW) interface standards, or others. They can also provide inline content (in a range of formats including the OGC Geography Markup Language (GML) and KML interface standards. The context document also passes styling information and metadata related to services or content. This is much more general purpose than previous attempts to pass context around.  And, in general, it has the benefit of being relatively compact (as it is typically carrying references rather than the data) and so it can be easily emailed around a community of interest, or held in a registry. 

Both XML and JSON Encodings are being developed, the latter easily exploitable in standard browser technology.

The OWS Context standard development came out of experimentation within the OGC Web Services Phase 7 Testbed (OWS-7) and has progressed to the point where a draft standard is imminent. Envitia are charter members of the OWS Context Standards Working Group (SWG). I am Editor of the Abstract Specification and, along with David Wesloh of the US National Geospatial Intelligence Agency (NGA), co-chair of the SWG. A draft of the Abstract Specification and Implementation Specifications for XML and JSON were presented at the OGC March Technical Meeting in Austin, Texas and the plan is to make a public draft available for the Exeter TC in June. Envitia have agreed to be an early implementer of the OWS Context Standard.