HTTP request rules |
At present, the only distributed computing platform (DCP) explicitly supported by OGC Web Services is the World Wide Web itself, or more specifically, Internet hosts implementing the Hypertext Transfer Protocol (HTTP). Thus the Online Resource of each operation supported by a service instance is located by an HTTP Uniform Resource Locator (URL).
HTTP supports two request methods: GET and POST. One or both of these methods may be defined for a particular OGC Web Service type and offered by a service instance. The use of the Online Resource URL differs in each case.
An Online Resource URL intended for HTTP GET requests, is, in fact, only a URL prefix to which additional parameters must be appended in order to construct a valid Operation request. A URL prefix is defined as an opaque string including the protocol, hostname, optional port number, path, a question mark '?', and, optionally, one or more server-specific parameters ending in an ampersand '&'. The prefix uniquely identifies the particular service instance. A client appends the necessary request parameters as name/value pairs in the form "name=value&". The resulting URL must be valid according to the HTTP Common Gateway Interface (CGI) standard.
The URL prefix must end in either a '?' (in the absence of additional server-specific parameters) or a '&'.
Table 1 A general OGC Web Service Request
| URL Component | Description |
| http://host[:port]/path?{name[=value]&} |
Description [] reprents the optional part, this part may appear 0 or 1 times. {} indicates this part can appear 0 or many times. The prefix is entirely at the discretion of the service provider. |
| name=value& |
One or more standard request parameter name/value pairs defined by an OGC Web Service. The actual list of required and optional parameters is mandated for each operation by the appropriate OWS specification. |
An Online Resource URL intended for HTTP POST requests is a complete and valid URL to which Clients transmit encoded requests in the body of the POST document. A WFS must not require additional parameters to be appended to the URL in order to construct a valid target for the Operation request.