Copyright © 2010 Open Geospatial Consortium Inc.
39 When a WMTS server responds with an ExceptionReport and the report is transmitted
via HTTP, the WMTS server should set the status code of the HTTP response to the corresponding value for the given exceptionCode values, as shown in Table 21. When the
ExceptionReport contains more than one Exception, then the HTTP status code value should be based upon the exceptionCode of the first Exception in the ExceptionReport.
Table 21 — HTTP exception codes and meanings on GetCapabilities operation
exceptionCode value HTTP Status Code
Code Message
MissingParameterValue 400
Bad request InvalidParameterValue
400 Bad request
VersionNegotiationFailed 400
Bad request InvalidUpdateSequence
400 Bad request
NoApplicableCode 500
Internal server error
7.1.3 ServiceMetadata resource request mandatory in resource oriented architectural
style
WMTS servers using a resource oriented architectural style provide standard endpoints from which a representation of the ServiceMetadata resource can be obtained. The
endpoint SHALL also be specified in the ServiceMetadata document although it will generally be obtained prior to communication with the server.
The client will request the representation of the ServiceMetadata resource by performing a standard request to the endpoint. In response to a correct request, the server SHALL
provide a representation of its ServiceMetadata document which conforms with subclause 7.1.1. Incorrect requests shall be handled according to the standard semantics for errors
for the transport protocol used for communication between the client and the server.
7.2 Tile
WMTS servers are designed to serve map image tiles. The ServiceMetadata document described in the previous subclause lists the tiles available on the server and the
requirements for requesting a tile. Typically clients will first request the ServiceMetadata document from the server and then use the information in that document to discover how
to perform valid requests for tiles.
40
Copyright © 2010 Open Geospatial Consortium Inc.
7.2.1 Tile resource
The tile resource is generally a rectangular image containing cartographic data. Alternatively, this resource might be a non-image representation of the tile such as a
description of the tile or a link to the actual image. For example, the tile resource could be a KML document used in a superoverlay, or a tile metadata document. When returning
an image tile, a full single tile SHALL always be returned. Also, the background pixels of a tile SHOULD be transparent when possible so that the client can overlay the tiles on top
of other map data possibly other tiles.
The Tile resource representation SHALL be returned in the format specified in the request when the format has been advertised in the ServiceMetadata document as
available for that Tile resource.
7.2.2 GetTile operation mandatory in procedure oriented architectural style
The GetTile operation in procedure oriented architectural style allows WMTS clients to request a particular tile of a particular tile matrix set in a predefined format. This
operation has some parameters in common with WMS GetMap but it has been deliberately simplified. For instance, only one layer can be retrieved at a time. WMTS
servers that want to allow a combination of layers to be served and requested have to give this combination an identifier and add it as a new layer in the service metadata document.
Nevertheless, clients are expected to be able easily to overlay layers themselves eliminating the need for servers to offer layers by combination.
7.2.2.1 GetTile operation request
A request to perform the GetTile operation SHALL use the data structure specified in Table 22. This table also specifies the UML model data type, source of values, and
multiplicity of each listed parameter, plus the default server behavior when an optional parameter is not included in the operation request.
