Public Comment on OpenGIS Web Coverage Service Extensions
OGC Requests Comments on Web Coverage Standard Extensions
June 30, 2008. Wayland, MA, USA.
The Open Geospatial Consortium, Inc. (OGC) membership approved a 30-day public comment period for a revision to the OpenGIS Web Coverage Service (WCS) Interface Standard. The revision includes two extensions to WCS: the WCS 1.1 Transaction Extension and the Web Coverage Processing Service Processing (WCPS) Extension.
The WCS Interface Standard (http://www.opengeospatial.org/standards/wcs) specifies an application programming interface (API) for requesting coverage data, such as imagery, from one or more distributed sources.
The WCS 1.1 Transaction Extension defines how WCS clients can request that a WCS server import one or more new coverages into that server, update existing coverages, and/or delete existing coverages.
The WCPS Extension adds a raster expression language to WCS which allows analysis and processing of multi-dimensional grid coverage data over the World Wide Web. Resulting coverages can be transmitted directly or made available for download by URLs communicated to the client.
The Request for Comments (RFC) document can be downloaded from http://www.opengeospatial.org/standards/requests/49. Comments are due by July 30, 2008.
The OGC is an international consortium of more than 365 companies, government agencies, research organizations, and universities participating in a consensus process to develop publicly available geospatial standards. OpenGIS Standards support interoperable solutions that "geo-enable" the Web, wireless and location-based services, and mainstream IT. OGC Standards empower technology developers to make geospatial information and services accessible and useful with any application that needs to be geospatially enabled. Visit the OGC website at:
Executive Director, Outreach and Community Adoption
Open Geospatial Consortium, Inc
35 Main Street, Suite 5, Wayland, MA 01778 USA
Adapted from the text of Web Coverage Service (WCS) Implementation Standard Version 1.1.2:
The specified Web Coverage Service (WCS) interface supports electronic retrieval of geospatial data as "coverages" — that is, digital geospatial information representing space-varying phenomena. A WCS provides access to potentially detailed and rich sets of geospatial information, in forms that are useful for client-side rendering and input into scientific models and other clients.
A WCS provides access to potentially detailed and rich sets of geospatial information, in forms that are useful for client-side rendering, multi-valued coverages, and input into scientific models and other clients. The WCS may be compared to the OGC Web Map Service (WMS) and the Web Feature Service (WFS); like them it allows clients to choose portions of a server's information holdings based on spatial constraints and other criteria.
The WCS interface specifies three operations that may be requested by a WCS client and performed by a WCS server:
GetCapabilities (required implementation by servers) — This operation allows a client to request the service metadata (or Capabilities) document. This XML document describes the abilities of the specific server implementation, usually including brief descriptions of the coverages available on the server. This operation also supports negotiation of the specification version being used for client-server interactions. Clients would generally request the GetCapabilities operation and cache its result for use throughout a session, or reuse it for multiple sessions. When the GetCapabilities operation does not return descriptions of its available coverages, that information must be available from a separate source, such as an image catalog.
DescribeCoverage (required implementation by servers) — This operation allows a client to request full descriptions of one or more coverages served by a particular WCS server. The server responds with an XML document that fully describes the identified coverages.
GetCoverage (required implementation by servers) — This operation allows a client to request a coverage comprised of selected range properties at a selected set of geographic locations. The server extracts the response data from the selected coverage, and encodes it in a known coverage format. The GetCoverage operation is normally run after GetCapabilities and DescribeCoverage operation responses have shown what requests are allowed and what data are available.