WMS 1.1.1 |
WMS 1.1.1 defines three operations: GetCapabilities, GetMap and GetFeatureInfo, where GetFeatureInfo is optional. WMS specifies the implementation and usage that WMS operation is in HTTP (Hypertext Transfer Protocol) Distributed Computing Platform，DCP. The future version may support other DCP.
GetCapabitities, returns service-level metadata.
GetMap, returns a map image whose geospatial and dimensional parameters are well-defined.
GetFeatureInfo, returns information about particular features shown on a map.
This specification defines a syntax for World Wide Web(WWW)Uniform Resource Locators(URLs)that invoke each of these operations. Also, an Extensible Markup Language(XML)encoding is defined for service-level metadata.
When requesting a map, a client may specify the information to be shown on the map(one or more "Layers"),possibly the "Styles" of those Layers, what portion of the Earth is to be mapped(a "Bounding Box"),the projected or geographic coordinate reference system to be used(the "Spatial Reference System," or SRS),the desired output format, the output size(Width and Height),and background transparency and color.When requesting a WMS service, parameters to be passed are contained in the URL in the form of the parameter name=the parameter value. For example, the address of a WMS service is: http://server/services/wms. When implementing the GetCapabilities operation, required parameters are SERVICE, REQUEST, and the values are WMS, GetCapabilities respectively; then, the complete URL is: http://server/services/wms?&map=world&SERVICE=WMS&REQUEST=GetCapabilities. Parameter names are case insensitive, and parameters can be arranged in an arbitrary order. Parameter values are case sensitive, however, the service ignores the case of some parameter values considering the error tolerance. The URL should be encoded according to W3C standards.