Web Map Service (WMS) is a standard protocol for serving geo-referenced map images over the Internet that are generated by a map server. The WMS layer is a raster layer that can show the map images generated by Map Servers compliant with WMS version 1.1.1 or 1.3.0.
The UConfiguration for this raster layer type you can define the parameters necessary to access the WMS and get the map images. The supported values for most settings are announced by the WMS. If you know the Server URI of the WMS you can easily get supported settings for that WMS by issuing a GetCapabilities request like http://gis.lebensministerium.at/wmsgw/dopmaxresfree/?VERSION=1.3.0&REQUEST=GetCapabilities&SERVICE=WMS . However Clients like the Smart Client usually do this for you and will present the possible setting for the configured WMS.
Table 1 lists the settings in the UConfiguration for this layer type. Besides this common settings you can define one or multiple layers to be retrieved from the WMS, table 2 shows the parameters you can set for each of these layers.
Setting |
Description |
Defines Zoom Extent |
If set the raster images received from the WMS will add to the Zoom extent of the map. |
WMS Settings |
This Structured data setting of the UConfiguration defines all the details needed to query data from WMS. See table 2 for details. |
Table 1: Settings in the UConfiguration of the WMS maps layer type
Setting |
Description |
WMS URL |
Mandatory. The URL (address) where the WMS is hosted. Examples: •http://gis.lebensministerium.at/wmsgw/dopmaxresfree/ •http://mesonet.agron.iastate.edu/cgi-bin/wms/goes/west_vis.cgi? |
WMS User name |
Optional. If the WMS Server you connect to requires authentication specify your user name here. |
WMS Password |
Optional. If the WMS Server you connect to requires authentication specify your password here. |
Coordinate reference system |
Mandatory. Name of the coordinate system in which the data shall be delivered by the WMS. See below for a detailed discussion on Coordinate Reference Systems The Coordinate Reference System setting corresponds to the CRS (WMS version 1.3.0) or SRS (previous WMS versions) parameter in a WMS GetMap request |
Min X |
Defines the bounding box for zoom extents. |
Min Y |
Defines the bounding box for zoom extents. |
Max X |
Defines the bounding box for zoom extents. |
Max Y |
Defines the bounding box for zoom extents. |
Axis inverted |
Defines if X and Y are inverted. |
Extra parameters |
Optional. Some servers might require or might support extra parameters for a GetMap Request. This setting allows you to specify those extra parameters. Use <key>=<value> syntax to specify parameters. Multiple parameters must be separated by comma e.g. key1=value1, key2=value2 |
Output format |
Mandatory. The output format in which the WMS Server will return the images. Corresponds to the WMS Request parameter FORMAT for GetMap requests. |
Exception format |
Optional. Upon receiving a request that is invalid according to the WMS standard, the WMS server will issue a service exception report. The service exception report is meant to describe to the client application or its human user the reason(s) that the request is invalid. The exceptions setting indicates the format in which the client wishes to be notified of service exceptions that arise during the request for a map. Corresponds to the WMS Request parameter EXCEPTIONS for GetMap requests. |
Background color |
Optional, default is white (RGB 255,255,255) This setting specifies the color to be used as the background for no-data areas, if either Background transparency is set to false or the chosen output format does not support transparency. The Background Transparency setting corresponds to the BGCOLOR parameter in a WMS GetMap request |
Table 1: Common settings in the UConfiguration of the WMS layer.
Setting |
Description |
Layer |
Mandatory. The name of the layer that shall be loaded from the WMS. The layer setting of all layers defined will be used to generate the LAYERS parameter for the WMS Request. |
Style |
Mandatory. The style in which the layer shall be loaded from the WMS. The style setting of all defined layers will be used to generate the STYLES parameter for the WMS Request. |
Table 2: Settings available for each layer in a WMS layer
WMS Version
There are different versions of the WMS standard. Redbex supports Version 1.1.1 and Version 1.3.0. When trying to load maps from a WMS Redbex will try to use Version 1.3.0 but will fall back to version 1.1.1 if the Server does not support 1.3.0.
Coordinate Reference System
The Coordinate reference system setting states what coordinate reference system applies to the WMS requests, i.e. what coordinate reference system is used for defining the area for which maps shall be returned and what coordinate system the returned maps are in. The value of the Coordinate reference system setting must be one one of the values defined by the WMS-Server, i.e. the WMS defines which coordinate reference systems are available.
Since WMS servers do not provide full definitions of coordinate systems Redbex cannot transform (re-project) data from WMS server. It is up to the user to choose a coordinate reference system that matches the reference system of your Map View Template.
