TJS GetData Operation

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TJS GetData Operation


The GetData operation provides a means for a client to retrieve attribute data. The response includes descriptive information about each attribute included in the response, as well as the attribute values for all selected records. The attribute values are returned to a client as an XML document, in GDAS format.


GetData Request

Parameters

Name Presence Description
service Required Identifies service type. Must be "TJS".
request Required Identifies service request. Must be "GetData"
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 spatial framework, as indicated in the DescribeFrameworks response.
DatasetURI Required The URI of the attribute dataset, as indicated in the DescribeDatasets response.
Attributes Optional The AttributeNames requested by the user, in comma-delimited format.
LinkageKeys Optional The DatasetKey identifiers requested by the user. Identifiers shall be in comma-delimited format, where ranges shall be indicated with a minimum value and maximum value separated by a dash ("-"). The same Identifier cannot be requested multiple times.
FilterColumn Optional The name of a Nominal or Ordinal field in the dataset upon which to filter the contents of the GetData response. If this parameter is absent, the response shall include all linkage keys available for the requested dataset (i.e all dataset rows) apart from those not identified for inclusion by the LinkageKeys parameter.
FilterValue Optional The Nominal or Ordinal value which the contents of the GetData response shall match. If this parameter is absent, the response shall include all linkage keys available for the requested dataset (i.e all dataset rows) apart from those not identified for inclusion by the LinkageKeys parameter.
XSL Optional The URL of a valid XSLT document that shall be referenced in the response. (Note that the XSL file must be accessible via the same server and port number as the GDAS GetData operation, since cross-domain XSLT references are not supported by most web browsers.)
Aid Optional Boolean value used to request the inclusion of an attribute identifiers in the Rowset portion of the response. When "Aid" is set to "true", an "aid" attribute will be included with each "V" found in the response. Default is "false".

Methods

HTTP GET method using KVP (mandatory)

All TJS servers shall implement HTTP GET transfer of the GetData request, using KVP encoding. The KVP encoding of the GetData request shall use the parameters specified above. An example of a GetData request via HTTP GET is:

http://foo.bar/foo?
   service=TJS&
   request=GetData&
   version=1.0&
   language=en&
   FrameworkURI=http://nrcan.gc.ca/Provinces/2001&
   DatasetURI=http://statcan.ca/2001Census&
   Attributes=cattlecalves,cows&
   LinkageKeys=10,11,12,13,24,35,46-48&
   XSL=http://foo.bar/foo&
   Aid=false

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 GetData operation request, using XML encoding only. The request parameters are encoded as XML elements, with their contents equivalent to those indicated in the parameter table shown above, and encoded according to the GetData request XML schema. The following example indicates the contents and structure of a GetData operation request encoded in XML.

<GetData service="TJS" version="1.0" language="en">
  <FrameworkURI>http://nrcan.gc.ca/Provinces/2001</FrameworkURI>
  <DatasetURI>http://statcan.ca/2001Census</DatasetURI>
  <Attributes>cattlecalves,cows</Attributes>
  <LinkageKeys>10-13,24,35,46-48,59</LinkageKeys>
  <XSL>http://www.ogcnetwork.net/schemas/tjs/1.0/examples_xslt/gdas2html2.xsl</XSL>
</GetData>



GetData Response

Schema

The normal response to a valid GetData operation request shall be a GDAS data structure, which encodes attribute data along with associated metadata. GDAS is encoded in XML according to the GetData response XML schema.

Examples


Exceptions

When a TJS server encounters an error while performing a GetData 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.