wmsref

Demis WMS reference

The OpenGIS Web Mapping protocol as initially defined by the 1.0.0 Specifications is a fairly open and flexible standard in the sense that in order to be WMS compliant, a server implementation is not required to support each and every feature that the specifications allow.

For example, the WMS specification mentions many image formats that can be requested (GIF, JPEG, PNG, TIFF, GeoTIFF, PPM, WBMP). However, server implementations are NOT required to support each of these formats. Instead, the server can indicate which image formats are supported when a Capabilities request is posted to the server.

Also, the specification allows vendor specific parameters to be implemented for extended functionality.

With the release of the 1.1.0 and 1.1.1 WMS specifications, some syntax changes were made and some additional features were added to the WMS protocol. Demis WMS 4.0 can be used with either of these protocol versions.

The following tables summarize the most important limitations and vendor specific parameters of the Demis Web Map Server implementation.

WMS Parameter Implementation
WMSVER / VERSION Version 1.0.0 / 1.1.0 / 1.1.1 / 1.3.0 of the WMS specification are supported
SRS No reprojection capabilities are provided, the requested coordinate system (a.k.a. SRS or CRS) must match that of the map data.
FORMAT PNG / JPEG / GIF / BMP / SWF image formats are supported.
STYLES / SLD There is no implementation of SLD (Styled Layer Descriptors) and by default, no fixed STYLES are advertised in the generated capabilities XML.
In fact, it is possible to specify RGB colors in hexadecimal format (0xRRGGBB) or standard HTML color names to change the color of vector layers, but since it did not seem to make sense to list all possible colors for each layer, we decided to make this an implicit behavior, which has rarely been used.
Other parameters Implemented fully according to WMS 1.0.0 / 1.1.0 / 1.1.1 specifications, including optional specifications
Vendor specific Implementation
QUALITY Image quality (as used by Cubewerx, may become part of future version WMS specification)
Value PNG format SWF format (Flash) JPEG format
QUICKEST 8 bit bitmap with palette 8 bit bitmap with palette Image quality 50 %
MEDIUM (default) 8 bit bitmap with palette 8 bit bitmap with palette Image quality 70 %
BEST 32 bit RGBA bitmap 32 bit RGBA bitmap Image quality 90 %
WRAPDATELINE By specifying WRAPDATELINE=TRUE you can allow maps which use Latitude-Longitude co-ordinates (EPSG:4326) to wrap across the dateline (+180 east to -180 west) Please note that as per 1.1.0 version of the OpenGIS WMS specification, the map will only wrap to the east (at 180+ longitudes) and not to the west. To effectively make the map “wrap” in both directions, you need to adjust your scripts to offset the longitude by +360 degrees if it goes beyond -180 degrees (i.e. -190 deg equals +170 deg)
LEGEND Adding LEGEND=X,Y as a parameter will cause a legend to display in the map at the X,Y coordinate specified in pixels (i.e. LEGEND=10,10) You cannot change the size of this legend as it is determined by default font size, length of the layer names etc.
Note: These vendor specific parameters are not part of the OpenGIS specifications, they offer special features that are specific to the Demis WMS implementation.