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| Author: | Jeff McKenna |
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| Contact: | jmckenna at gatewaygeomatics.com |
| Last Updated: | 2011-10-06 |
Table of Contents
A WMS (or Web Map Server) allows for use of data from several different servers, and enables for the creation of a network of Map Servers from which clients can build customized maps. The following documentation is based on the Open Geospatial Consortium’s (OGC) Web Map Server Interfaces Implementation Specification v1.1.1.
MapServer v3.5 or more recent is required to implement WMS features. At the time this document was written, MapServer supports the following WMS versions: 1.0.0, 1.0.7, 1.1.0 (a.k.a. 1.0.8), 1.1.1 and 1.3.0
This document assumes that you are already familiar with certain aspects of MapServer:
WMS servers interact with their clients via the HTTP protocol. In most cases, a WMS server is a CGI program. This is also the case with MapServer.
The WMS specification defines a number of request types, and for each of them a set of query parameters and associated behaviors. A WMS-compliant server MUST be able to handle at least the following 2 types of WMS requests:
And support for the following types is optional:
With respect to MapServer specifically, it is the “mapserv” CGI program that knows how to handle WMS requests. So setting up a WMS server with MapServer involves installing the mapserv CGI program and a setting up a mapfile with appropriate metadata in it. This is covered in the rest of this document.
WMS requests are handled by the mapserv CGI program. Not all versions of the mapserv program do include WMS support (it is included by default when you compile together with the PROJ library), so the first step is to check that your mapserv executable includes WMS support. One way to verify this is to use the “-v” command-line switch and look for “SUPPORTS=WMS_SERVER”.
(Unix users should refer to the Compiling on Unix document for any compiling instructions, and Windows users might want to use MS4W, which comes ready with WMS/WFS support)
Example 1. On Unix:
$ ./mapserv -v
MapServer version 4.6.1 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP OUTPUT=PDF
OUTPUT=SWF OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER
SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER
INPUT=JPEG INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE DEBUG=MSDEBUG
Example 2. On Windows:
C:\apache\cgi-bin> mapserv -v
MapServer version 4.6.1 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP OUTPUT=PDF
OUTPUT=SWF OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER
SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER
INPUT=JPEG INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE DEBUG=MSDEBUG
Each instance of WMS server that you setup needs to have its own mapfile. It is just a regular MapServer mapfile in which some parameters and some metadata entries are mandatory. Most of the metadata is required in order to produce a valid GetCapabilites output.
Here is the list of parameters and metadata items that usually optional with MapServer, but are required (or strongly recommended) for a WMS configuration:
At the MAP level:
And for each LAYER:
Let’s go through each of these parameters in more detail:
Map Name and wms_title:
WMS Capabilities requires a Name and a Title tag for every layer. The Map’s NAME and wms_title metadata will be used to set the root layer’s name and title in the GetCapabilities XML output. The root layer in the WMS context corresponds to the whole mapfile.
Layer Name and wms_title metadata:
Every individual layer needs its own unique name and title. Layer names are also used in GetMap and GetFeatureInfo requests to refer to layers that should be included in the map output and in the query. Layer names must start with a letter when setting up a WMS server (layer names should not start with a digit or have spaces in them).
Map PROJECTION and wms_srs metadata:
WMS servers have to advertise the projection in which they are able to serve data using EPSG projection codes (see The EPSG web page for more background on EPSG codes). Recent versions of the PROJ4 library come with a table of EPSG initialization codes and allow users to define a projection like this:
PROJECTION
"init=epsg:4269"
END
(Note that “epsg” has to be in lowercase when used in the PROJ4 ‘init’ directive.)
If the MAP PROJECTION block is provided in the format “init=epsg:xxxx” then MapServer will also use this information to generate a <BoundingBox> tag for the top-level layer in the WMS capabilities document. BoundingBox is a mandatory element of WMS capabilities for WMS 1.3.0 (for WMS 1.1.0 it is optional, but it is good practice to allow MapServer to include it when possible).
The above is sufficient for MapServer to recognize the EPSG code and include it in SRS tags in the capabilities output (wms_srs metadata is not required in this case). However, it is often impossible to find an EPSG code to match the projection of your data. In those cases, the “wms_srs” metadata is used to list one or more EPSG codes that the data can be served in, and the PROJECTION object contains the real PROJ4 definition of the data’s projection.
Here is an example of a server whose data is in an Lambert Conformal Conic projection (42304). It’s capabilities output will advertize EPSG:4269 and EPSG:4326 projections (lat/lon), but the PROJECTION object is set to the real projection that the data is in:
NAME "DEMO"
...
WEB
...
METADATA
"wms_title" "WMS Demo Server"
"wms_onlineresource" "http://my.host.com/cgi-bin/mapserv?map=wms.map&"
"wms_srs" "EPSG:4269 EPSG:4326"
END
END
PROJECTION
"init=epsg:42304"
END
...
END
In addition to EPSG:xxxx projections, a WMS server can advertize projections in the AUTO:xxxx namespace. AUTO projections 42001 to 42005 are internally supported by MapServer. However, AUTO projections are useful only with smart WMS clients, since the client needs to define the projection parameters in the WMS requests to the server. For more information see Annex E of the WMS 1.1.1 specification and section 6.5.5.2 of the same document. See also the FAQ on AUTO projections at the end of this document.
Layer PROJECTION and wms_srs metadata:
By default layers inherit the SRS of their parent layer (the map’s PROJECTION in the MapServer case). For this reason it is not necessary (but still strongly recommended) to provide PROJECTION and wms_srs for every layer. If a layer PROJECTION is not provided then the top-level map projecion will be assumed.
Layer PROJECTION and wms_srs metadata are defined exactly the same way as the map’s PROJECTION and wms_srs metadata.
For vector layers, if a PROJECTION block is provided in the format “init=epsg:xxxx” then MapServer will also use this information to generate a <BoundingBox> tag for this layer in the WMS capabilities document. BoundingBox is a mandatory element of WMS capabilities for WMS 1.3.0 (for WMS 1.1.0 it is optional, but it is good practice to allow MapServer to include it when possible).
“wms_onlineresource” metadata:
The wms_onlineresource metadata is set in the map’s web object metadata and specifies the URL that should be used to access your server. This is required for the GetCapabilities output. If wms_onlineresource is not provided then MapServer will try to provide a default one using the script name and hostname, but you shouldn’t count on that too much. It is strongly recommended that you provide the wms_onlineresource metadata.
See section 6.2.2 of the WMS 1.1.1 specification for the whole story about the online resource URL. Basically, what you need is a complete HTTP URL including the http:// prefix, hostname, script name, potentially a “map=” parameter, and and terminated by ”?” or “&”.
Here is a valid online resource URL:
http://my.host.com/cgi-bin/mapserv?map=mywms.map&
By creating a wrapper script on the server it is possible to hide the “map=” parameter from the URL and then your server’s online resource URL could be something like:
http://my.host.com/cgi-bin/mywms?
This is covered in more detail in the section “More About the Online Resource URL” below.
“wms_enable_request” metadata:
Specify which requests to enable. If not specified, no requests will be enabled! See the explanation below.
Configuring for GetFeatureInfo Requests:
You must set the layer TEMPLATE parameter for the layer to be queryable by GetFeatureInfo requests (see Templating). For requests of type “text/html” you should also set the layer HEADER and FOOTER parameters.
As of MapServer 4.6 you must set the gml_* metadata for the layer attributes to be served (see the Layer Object metadata in the Reference Section later in this document). To include geometry, gml_geometries and gml_[geometry name]_type has to be specified.
Here are working examples of GetFeatureInfo requests: text/plain / text/html / gml (for gml, your browser might ask you to save the file, if so save it locally as a .gml file and view it in a text editor)
OK, now that we’ve got a mapfile, we have to check the XML capabilities returned by our server to make sure nothing is missing.
Using a web browser, access your server’s online resource URL to which you add the parameters “SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities” to the end, e.g.
http://my.host.com/cgi-bin/mapserv?map=mywms.map&SERVICE=WMS&VERSION=1.1.1
&REQUEST=GetCapabilities
Here is a working GetCapabilities request (note that the SERVICE parameter is required for all GetCapabilities requests):
http://demo.mapserver.org/cgi-bin/wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities
This should return a document of MIME type application/vnd.ogc.wms_xml, so your browser is likely going to prompt you to save the file. Save it and open it in a text editor (Emacs, Notepad, etc.), and you will see the returned XML from the WMS server.
If you get an error message in the XML output then take necessary actions. Common problems and solutions are listed in the FAQ at the end of this document.
If everything went well, you should have a complete XML capabilities document. Search it for the word “WARNING”... MapServer inserts XML comments starting with “<!–WARNING: ” in the XML output if it detects missing mapfile parameters or metadata items. If you notice any warning in your XML output then you have to fix all of them before you can register your server with a WMS client, otherwise things are likely not going to work.
Note that when a request happens, it is passed through WMS, WFS, and WCS in MapServer (in that order) until one of the services respond to it.
OK, now that we know that our server can produce a valid XML GetCapabilities response we should test the GetMap request. MapServer only checks for a few of the required GetMap parameters, so both of the minimum MapServer parameters and a valid GetMap request will be explained below.
The following is a list of the required GetMap parameters according to the WMS spec:
VERSION=version: Request version
REQUEST=GetMap: Request name
LAYERS=layer_list: Comma-separated list of one or more map layers. Optional if SLD parameter is present.
STYLES=style_list: Comma-separated list of one rendering style per requested layer. Optional if SLD parameter is present. Set “STYLES=” with an empty value to use default style(s). Named styles are also supported and are controlled by CLASS GROUP names in the mapfile.
SRS=namespace:identifier: Spatial Reference System.
BBOX=minx,miny,maxx,maxy: Bounding box corners (lower left, upper right) in SRS units.
WIDTH=output_width: Width in pixels of map picture.
HEIGHT=output_height: Height in pixels of map picture.
FORMAT=output_format: Output format of map.
Note
WMS Servers only advertise supported formats that are part of the gd / gdal libraries.
A valid example would therefore be:
http://my.host.com/cgi-bin/mapserv?map=mywms.map&SERVICE=WMS&VERSION=1.1.1
&REQUEST=GetMap&LAYERS=prov_bound&STYLES=&SRS=EPSG:4326
&BBOX=-173.537,35.8775,-11.9603,83.8009&WIDTH=400&HEIGHT=300
&FORMAT=image/png
Here is a working valid request.
If you have access to a WMS client, then register your new server’s online resource with it and you should be off and running.
If you don’t have your own WMS client installed already, here are a few pointers:
This list is not exhaustive, there are several Open Source or proprietary packages that offer WMS support and could be used to interact with your new MapServer WMS server instance.
This request returns a legend image (icon) for the specified layer. The request will draw an icon and a label for all classes defined on the layer. If the requested layername is a GROUP-name, all included layers will be returned in the legend-icon.
The following are required in the WMS server mapfile to enable this request:
The following are valid parameters for this request:
- LAYER - (Required) Name of the WMS layer to return the legend image of. Note that this is the <Name> parameter of the Layer in the GetCapabilities.
- FORMAT - (Required) Format of the legend image (e.g. “image/png”).
- WIDTH - (Optional) Width of the legend image. Note that the Width parameter is only used when the Rule parameter is also used in the request.
- HEIGHT - (Optional) Height of the legend image. Note that the Height parameter is only used when the Rule parameter is also used in the request.
- SLD - (Optional) The URL to the SLD. Applies the SLD on the layer and the legend is drawn after the SLD is applied (using the classes specfied by the SLD). Note here that you need to put a <Name>class1</Name> inside the Rule element so that a class name is created from the SLD and therefore a correct legend image.
- SLD_BODY - (Optional) The body (code) of the SLD, instead of specifying a URL (as in the ‘SLD’ parameter).
- SLD_VERSION - (Optional) The SLD version.
- SCALE - (Optional) Specify a scale so that only layers that fall into that scale will have a legend.
- STYLE - (Optional) The style.
- RULE - (Optional) Specify the name of the CLASS to generate the legend image for (as opposed to generating an icon and label for ALL classes for the layer).
Note
All rules that are used to draw the legend in normal CGI mode apply here. See the CGI Reference doc if necessary.
The CLASS object’s KEYIMAGE parameter can also be used to specify a legend image for a CLASS. See the MapFile Reference doc if necessary. Example Request
An example request might look like:
http://127.0.0.1/cgi-bin/mapserv.exe?SERVICE=WMS&VERSION=1.1.1&layer=park&
REQUEST=getlegendgraphic&FORMAT=image/png
As mentioned in the section “Setup a Mapfile / wms_onlineresource metadata” above, the following Online Resource URL is perfectly valid for a MapServer WMS according to section 6.2.2 or the WMS 1.1.1 specification:
http://my.host.com/cgi-bin/mapserv?map=mywms.map&
However, some people will argue that the above URL contains mandatory vendor-specific parameters and that this is illegal. First we would like to point that “map=...” is not considered a vendor-specific parameter in this case since it is part of the Online Resource URL which is defined as an opaque string terminated by ”?” or “&” (See WMS 1.1.1 section 6.2.2).
But anyway, even if it’s valid, the above URL is still ugly. And you might want to use a nicer URL for your WMS Online Resource URL. Here are some suggestions:
One can use Apache’s mod_rewrite to avoid specifying the map, or any other default parameter in the mapserver URL. This task consist of three steps, specifying the mod_rewrite module to be loaded, enabling the mod_rewrite module for the selected directories and at last to write a .htaccess file to do the rewriting.
In the httpd.conf file, the mod_rewrite module is per default disabled. To enable it, remove the opening # in the line
#LoadModule rewrite_module modules/mod_rewrite.so
To be able to use the module, it must be enabled, using the directive AllowOverride. This can be done per server or per directory. If you just have one server, add an “AllowOverride All” line in the httpd.conf file (see the Apache documentation to be sure about the security implications of this). Per directory is the easiest way to make it work on virtual hosts. Within the <virtualHost> section of the httpd.conf insert:
<Directory myhtdocsdir>
AllowOverride All
</Directory>
Where myhtdocsdir is the directory defined as documentroot for the actual virtual server.
When the directives are set to load and enable the mod_rewrite module, Apache has to be restarted.
In a web-accessible directory make a .htaccess file like the following:
RewriteEngine on
RewriteRule wmsmap?(.*) /cgi-bin/mapserv?map=/home/www/mapserverstuff/mymapfile.map&$1
The rewriteRule says: given a webpage starting with wmsmap, pick out the query parameters, make a new page request starting with /cgi-bin/mapserv?map=(…)? and add on whatever was the query parameters in the original page request.
e.g, the URL wmsmap?mode=map will be rewritten as
If just the URL wmsmap is given (without any parameters) a page not found error will show up as that does not match the wmsmap? expression.
A default mapfile can be specified using the MS_MAPFILE environment variable:
Alias /mywms /usr/lib/cgi-bin/mapserver
<Location /mywms>
SetHandler cgi-script
Options ExecCGI
SetEnv MS_MAPFILE /path/to/mymapfile.map
</Location>
Another option is to use the “setenvif” feature of Apache: use symbolic links that all point to a same mapserv binary, and then for each symbolic link test the URL, and set the MAP environment accordingly.
For Windows and Apache users the steps are as follows (this requires Apache 1.3 or newer):
SetEnvIf Request_URI "/cgi-bin/mywms" MS_MAPFILE=/path/to/mymap.map
On IIS servers (Windows), you can use the following ASP script:
Note
The script below, while functional, is intended only as an example of using ASP to filter MapServer requests. Using ASP in a production WMS server will likely require additional ASP especially in the area of error handling and setting timeouts.*
<%
Server.ScriptTimeout = 360
Select Case Request.ServerVariables("REQUEST_METHOD")
Case "GET" strRequest = Request.QueryString
Case "POST" strRequest = Request.Form
End Select
strURL = "http://myserver/cgi-bin/mapserv.exe?
map=C:\Inetpub\wwwroot\workshop\itasca.map&" & strRequest
Dim objHTTP
Set objHTTP = Server.CreateObject("MSXML2.ServerXMLHTTP")
objHTTP.open "GET", strURL, false
objHTTP.send ""
Response.ContentType = objHTTP.getResponseHeader("content-type")
Response.BinaryWrite objHTTP.responseBody
Set objHTTP = Nothing
%>
Some OGC services (WFS, SOS) support both GET and POST requests. Here, you can use a minimal MapScript WxS wrapper. Here’s a Python example:
#!/usr/bin/python
import mapscript
req = mapscript.OWSRequest()
req.loadParams()
map = mapscript.mapObj('/path/to/config.map')
map.OWSDispatch(req)
On Unix servers, you can setup a wrapper shell script that sets the MS_MAPFILE environment variable and then passes control to the mapserv executable... that results on a cleaner OnlineResource URL:
#! /bin/sh
MS_MAPFILE=/path/to/demo.map
export MS_MAPFILE
/path/to/mapserv
Note
Using a /bin/sh wrapper script causes an overhead on system resources as two processes have to be spawned instead of one, and is therefore not recommended.
MapServer 5.4 adds support for WMS 1.3.0. Although the general mechanism in MapServer to support this new specification are the same, there are some notable upgrades.
The most notable changes introduced in WMS 1.3.0 are the:
The axis order in previous versions of the WMS specifications was to always use easting (x or lon ) and northing (y or lat). WMS 1.3.0 specifies that, depending on the particular CRS, the x axis may or may not be oriented West-to-East, and the y axis may or may not be oriented South-to-North. The WMS portrayal operation shall account for axis order. This affects some of the EPSG codes that were commonly used such as ESPG:4326. MapServer 5.x makes sure that coordinates passed to the server (as part of the GetMap BBOX parameter) as well as those advertised in the capabilities document reflect the inverse axe orders for EPSG codes between 4000 and 5000.
MapServer 6.0 and up holds a list of epsg codes with inverted axis order. It is currently based on EPSG database version 7.6. It is also possible to define the axis order at build time for a specific ESPG code(see #3582). This allows for example to use the “normal” axis order for some of EPSG codes between 4000 and 5000.
In addition, the WMS 1.3.0 defines a series of new coordinate system. These are the once that are currently supported in MapServer:
Users can use the CRS:84 coordinate system and order the BBOX coordinates as long/lat:
Users can also use the ESPG:4326 coordinates and use the axis odering of lat/long:
As of version 5.4, MapServer passes all the basic and query tests of the OGC CITE test suite for WMS 1.3.0.
The following metadata are available in the setup of the mapfile:
(Note that each of the metadata below can also be referred to as ‘ows_*’ instead of ‘wms_*’. MapServer tries the ‘wms_*’ metadata first, and if not found it tries the corresponding ‘ows_*’ name. Using this reduces the amount of duplication in mapfiles that support multiple OGC interfaces since “ows_*” metadata can be used almost everywhere for common metadata items shared by multiple OGC interfaces.)
ows_http_max_age
ows_schemas_location
ows_sld_enabled
ows_updatesequence
wms_abstract
wms_accessconstraints
wms_addresstype, wms_address, wms_city, wms_stateorprovince, wms_postcode, wms_country
wms_attribution_logourl_format
wms_attribution_logourl_height
wms_attribution_logourl_href
wms_attribution_logourl_width
wms_attribution_onlineresource
wms_attribution_title
provider.
refer to section 7.1.4.5.11 of the WMS 1.1.1 spec.
wms_bbox_extended:
wms_contactelectronicmailaddress
sect. 7.1.4.2)
Description: Optional contact Email address.
wms_contactfacsimiletelephone
wms_contactperson, wms_contactorganization, wms_contactposition
wms_contactvoicetelephone
wms_enable_request (or ows_enable_request)
Description: Space separated list of requests to enable. The default is none. The following requests can be enabled: GetCapabilities, GetMap, GetFeatureInfo and GetLegendGraphic. A ”!” in front of a request will disable the request. “*” enables all requests.
Examples:
To enable only GetMap and GetFeatureInfo:
"wms_enable_request" "GetMap GetFeatureInfo"
To enable all requests except GetFeatureInfo
"wms_enable_request" "* !GetFeatureInfo"
wms_encoding
wms_feature_info_mime_type
WMS TAG Name: Feature_info_mime_type
Description:
Used to specify an additional MIME type that can be used when responding to the GetFeature request.
For example if you want to use the layer’s HTML template as a base for its response, you need to add “WMS_FEATURE_INFO_MIME_TYPE” “text/html”. Setting this will have the effect of advertizing text/html as one of the MIME types supported for a GetFeature request. You also need to make sure that the layer points to a valid html template (see Templating). The client can then call the server with INFO_FORMAT=text/html.
If not specified, MapServer by default has text/plain and GML implemented.
wms_fees
wms_getcapabilities_version
wms_getlegendgraphic_formatlist
wms_getmap_formatlist
wms_keywordlist
wms_keywordlist_vocabulary
wms_keywordlist_[vocabulary’s name]_items
wms_languages
wms_layerlimit
wms_onlineresource
WMS TAG Name: OnlineResource (WMS1.1.1, sect. 6.2.2)
Description: (Recommended) The URL that will be used to access this WMS server. This value is used in the GetCapabilities response.
See also
Sections “Setup a Mapfile / wms_onlineresource metadata” and “More About the Online Resource URL” above.
wms_resx, wms_resy
wms_rootlayer_abstract
wms_rootlayer_keywordlist
wms_rootlayer_title
wms_service_onlineresource
Description: (Optional) Top-level onlineresource URL. MapServer uses the onlineresource metadata (if provided) in the following order:
3. wms_onlineresource (or automatically generated URL, see the onlineresource section of this document)
wms_srs
wms_timeformat
wms_title
gml_exclude_items
Description: (Optional, applies only to GetFeatureInfo GML requests) A comma delimited list of items to exclude. As of MapServer 4.6, you can control how many attributes (fields) you expose for your data layer with metadata. The previous behaviour was simply to expose all attributes all of the time. The default is to expose no attributes at all. An example excluding a specific field would be:
"gml_include_items" "all"
"gml_exclude_items" "Phonenum"
gml_geometries
gml_groups
gml_[group name]_group
Description: (Optional, applies only to GetFeatureInfo GML requests) A comma delimited list of attributes in the group. Here is an example:
"gml_include_items" "all"
"gml_groups" "display"
"gml_display_group" "Name_e,Name_f"
gml_include_items
Description: (Optional, applies only to GetFeatureInfo GML requests) A comma delimited list of items to include, or keyword “all”. As of MapServer 4.6, you can control how many attributes (fields) you expose for your data layer with this metadata. The previous behaviour was simply to expose all attributes all of the time. You can enable full exposure by using the keyword “all”, such as:
"gml_include_items" "all"
You can specify a list of attributes (fields) for partial exposure, such as:
"gml_include_items" "Name,ID"
The new default behaviour is to expose no attributes at all.
gml_[item name]_alias
Description: (Optional, applies only to GetFeatureInfo GML requests) An alias for an attribute’s name. The served GML will refer to this attribute by the alias. Here is an example:
"gml_province_alias" "prov"
gml_[item name]_type
gml_[geometry name]_type
gml_xml_items
wms_abstract
wms_attribution_logourl_format
wms_attribution_logourl_height
wms_attribution_logourl_href
wms_attribution_logourl_width
wms_attribution_onlineresource
wms_attribution_title
provider.
refer to section 7.1.4.5.11 of the WMS 1.1.1 spec.
wms_authorityurl_name, wms_authorityurl_href
wms_bbox_extended:
wms_dataurl_format
wms_dataurl_href
wms_enable_request (or ows_enable_request)
Description: Space separated list of requests to enable. The default is none. The following requests can be enabled: GetCapabilities, GetMap, GetFeatureInfo and GetLegendGraphic. A ”!” in front of a request will disable the request. “*” enables all requests.
Examples:
To enable only GetMap and GetFeatureInfo:
"wms_enable_request" "GetMap GetFeatureInfo"
To enable all requests except GetFeatureInfo
"wms_enable_request" "* !GetFeatureInfo"
wms_exclude_items
Description: (Optional, applies only to GetFeatureInfo text/plain requests) A comma delimited list of items to exclude, or keyword “all”.
See gml_exclude_items above.
wms_extent
WMS TAG Name: BoundingBox (WMS1.1.1, sect. 6.5.6)
Description: (Optional) Used for the layer’s BoundingBox tag for cases where it is impossible (or very inefficient) for MapServer to probe the data source to figure its extents. The value for this metadata is “minx miny maxx maxy” separated by spaces, with the values in the layer’s projection units. If wms_extent is provided then it has priority and MapServer will NOT try to read the source file’s extents.
For Rasters served through WMS, MapServer can now use the wms_extent metadata parameter to register the image. If a .wld file cannot be found, MapServer will then look for the wms_extent metadata parameter and use the extents of the image and the size of the image for georegistration.
wms_getfeatureinfo_formatlist
wms_getlegendgraphic_formatlist
wms_getmap_formatlist
wms_group_abstract
wms_group_title
wms_identifier_authority, wms_identifier_value
wms_include_items
Description: (Optional, applies only to GetFeatureInfo text/plain requests) A comma delimited list of items to include, or keyword “all”.
See gml_include_items above.
wms_keywordlist
wms_keywordlist_vocabulary
wms_keywordlist_[vocabulary’s name]_items
wms_layer_group
Description: (Optional) Can be used to assign a layer to a number of hierarchically nested groups. This grouped hierarchy will be expressed in the capabilities.
WMS_LAYER_GROUP is different from the GROUP keyword in that it does not necessarily publish the name of the group in the capabilities, only the title is always published. If a layer with the same name as used in WMS_LAYER_GROUP is found it is treated as named group and if no layer with this name is found as unnamed group.
As a consequence the groups set with WMS_LAYER_GROUP can not always be requested with a GetMap or GetFeatureInfo request (see section 7.1.4.5.2 of the WMS implementation specification version 1.1.1. (OGC 01-068r2)). Another difference is that GROUP does not support nested groups. The purpose of this metadata setting is to enable making a WMS client aware of layer grouping.
All group names should be preceded by a forward slash (/). It is not allowed to use both the WMS_LAYER_GROUP setting and the GROUP keyword for a single layer.
LAYER
NAME "mylayer"
DATA "mylayer"
TYPE LINE
CLASS
STYLE
COLOR 100 100 255
END
END
METADATA
"WMS_LAYER_GROUP" "/rootgroup/subgroup"
END
END
wms_metadataurl_format
wms_metadataurl_href
wms_metadataurl_type
wms_opaque
wms_srs
wms_style
wms_style_[style’s_name]_legendurl_format
wms_style_[style’s_name]_legendurl_height
wms_style_[style’s_name]_legendurl_href
wms_style_[style’s_name]_legendurl_width
wms_timedefault
wms_timeextent
wms_timeitem
wms_title
angle
Note
The angle value is in degrees clockwise.
radius
Currently, there are 3 requests that support WMS cascading:
GetMap
GetFeatureInfo
GetLegendGraphic
Before MapServer 6.2, a GetLegendGraphic request was not cascaded. A legend was returned using the layer classes. To preserve that behavior, a GetLegendGraphic request will be cascaded only if:
CLASS
NAME "Parks"
STYLE
COLOR 0 255 0
END
END
This layer won’t be cascaded because it contains at least a class with the property NAME set.
Note
If you know that the remote WMS server does not support a given WMS request, you should disable this request explicitly for your layer using the (ows/wms)_enable_request metadata. Otherwise, you will simply get the XML exception from the cascaded server.
The following is a very basic WMS Server mapfile:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | MAP
NAME "WMS-test"
STATUS ON
SIZE 400 300
EXTENT -2200000 -712631 3072800 3840000
UNITS METERS
SHAPEPATH "../data"
IMAGECOLOR 255 255 255
FONTSET ../etc/fonts.txt
WEB
IMAGEPATH "/ms4w/tmp/ms_tmp/"
IMAGEURL "/ms_tmp/"
METADATA
"wms_title" "WMS Demo Server" ##required
"wms_onlineresource" "http://yourpath/cgi-bin/mapserv.exe?" ##required
"wms_srs" "EPSG:42304 EPSG:42101 EPSG:4269 EPSG:4326" ##recommended
"wms_enable_request" "*" ##necessary
END
END # Web
PROJECTION
"init=epsg:42304" ##required
END
SYMBOL
NAME "circle"
TYPE ellipse
POINTS 1 1 END
END # Symbol
#
# Start of layer definitions
#
LAYER
NAME "park"
METADATA
"wms_title" "Parks" ##required
END
TYPE POLYGON
STATUS OFF
DATA park
PROJECTION
"init=epsg:42304" ##recommended
END
CLASS
NAME "Parks"
STYLE
COLOR 200 255 0
OUTLINECOLOR 120 120 120
END # Style
END # Class
END # Layer
LAYER
NAME popplace
METADATA
"wms_title" "Cities" ##required
END
TYPE POINT
STATUS ON
DATA popplace
PROJECTION
"init=epsg:42304" ##recommended
END
CLASS
NAME "Cities"
STYLE
SYMBOL "circle"
SIZE 8
COLOR 0 0 0
END # Style
END # Class
END # Layer
END # Map File
|
| Q: | How can I find the EPSG code for my data’s projection? |
|---|---|
| A: | If you know the parameters of your data’s projection, then you can browse the “epsg” file that comes with PROJ4 and look for a projection definition that matches your data’s projection. It’s a simple text file and the EPSG code is inside brackets (<...>) at the beginning of every line. The “epsg” file is usually located in /usr/local/share/proj/ on Unix systems and in C:/PROJ/ or C:/PROJ/NAD in Windows systems (depending on the installation). MS4W users will find the epsg file in /MS4W/proj/nad/. |
| Q: | My WMS server produces the error “msProcessProjection(): no system list, errno: ..” |
|---|---|
| A: | That’s likely PROJ4 complaining that it cannot find the “epsg” projection definition file. Make sure you have installed PROJ 4.4.3 or more recent and that the “epsg” file is installed at the right location. On Unix it should be under /usr/local/share/proj/, and on Windows PROJ looks for it under C:/PROJ/ or C:/PROJ/NAD (depending on the installation). You should also check the error documentation to see if your exact error is discussed. If you don’t have the “epsg” file then you can get it as part of the PROJ4 distribution at http://trac.osgeo.org/proj/ or you can download it at http://www.maptools.org/dl/proj4-epsg.zip. |
| Q: | How do AUTO projections work? |
|---|---|
| A: | When a WMS client calls a WMS server with an auto projection, it has to specify the SRS in the form: AUTO: proj_id,unit_id,lon0,lat0 where:
When using an AUTO projection in WMS GetCapabilities, you include only the “AUTO:42003” string in your wms_srs metadata, you do not include the projection parameters. Those are added by the application (client) at runtime depending on the map view. For example: NAME "DEMO"
...
WEB
...
METADATA
"wms_title" "WMS Demo Server"
"wms_onlineresource" "http://my.host.com/cgi-bin/mapserv?map=wms.map&"
"wms_srs" "AUTO:42001 AUTO:42002"
"wms_enable_request" "*" ##necessary
END # METADATA
END # WEB
The above server advertises the first two auto projections. |