The DescribeKey operation returns an XML document that identifies all of the keys for a spatial framework to which data can be joined by the service instance. This description also includes descriptive information about the spatial framework. This listing can be used to debug the JoinData operation, or to build a new attribute dataset for the spatial framework.
|service||Required||Identifies service type. Must be "TJS".|
|request||Required||Identifies service request. Must be "DescribeKey".|
|version||Required||Identifies service version. Defaults to the latest available version, currently 1.0.|
|language||Optional||Determines the language of the human-readable content of the response. Value is a two or five character IETF RFC 4646 language identifier.|
|FrameworkURI||Required||The URI of the framework dataset, as indicated in the DescribeFrameworks response.|
HTTP GET method using KVP (mandatory)
All TJS servers shall implement HTTP GET transfer of the DescribeKey request, using KVP encoding. The KVP encoding of the DescribeKey request shall use the parameters specified above. An example of a DescribeKey request via HTTP GET is:
Note: URL encoding of KVP values in this example has been removed for clarity.
HTTP POST method using XML (optional)
TJS servers may also implement HTTP POST transfer of the DescribeKey operation request, using XML encoding only. The request parameters are encoded as XML elements, with their contents identical to those indicated in the parameter table shown above according to the DescribeKey request XML schema. The following example indicates the contents and structure of a DescribeKey operation request encoded in XML.
<DescribeKey service="TJS" version="1.0" language="en">
The normal response to a valid DescribeKey operation request shall be a FrameworkKeyDescription data structure, which lists the entire contents of the FrameworkKey field for which the JoinData operation is supported on this service. This document is encoded in XML according to the DescribeKey response XML schema.
When a TJS server encounters an error while performing a DescribeKey operation, it shall return an exception report message as specified in Clause 8 of [OGC 06-121r3]. The allowed exception codes shall include those listed in Table 5 of Subclause 7.4.1 of [OGC 06-121r3].
For more information on structuring requests, please see the TJS Standard.