[mapserver-commits] r8703 - trunk/docs/tutorial
svn at osgeo.org
svn at osgeo.org
Mon Mar 9 11:51:19 EDT 2009
Author: pnaciona
Date: 2009-03-09 11:51:19 -0400 (Mon, 09 Mar 2009)
New Revision: 8703
Added:
trunk/docs/tutorial/example1-7.txt
Log:
add tutorial example 1.7: adding ogc wms layers
Added: trunk/docs/tutorial/example1-7.txt
===================================================================
--- trunk/docs/tutorial/example1-7.txt (rev 0)
+++ trunk/docs/tutorial/example1-7.txt 2009-03-09 15:51:19 UTC (rev 8703)
@@ -0,0 +1,127 @@
+.. _example1-7:
+
+===========
+Example 1.7
+===========
+Adding OGC WMS Layers
+---------------------
+
+.. image:: http://biometry.gis.umn.edu/cgi-bin/mapserv.exe?map=/ms4w/apps/tutorial/htdocs/example1-7.map&layers=states+states_label+modis_jpl&mode=map
+
+Another exciting feature of MapServer is its ability to use layers from other
+map servers. In this case, a MapServer application becomes a WMS (or WFS)
+client. MapServer can also share (or serve up) the layers in the mapfile to
+other map servers. This makes an application a WMS (or WFS) server. What is WMS
+or WFS? These are "web-based interoperability service" specifications published
+by the Open Geospatial Consortium (OGC). WMS stands for Web Map Service and WFS
+for Web Feature Service. The difference between these two specifications, in
+simple terms, is that WMS uses web raster formats (PNG, GIF, JPEG) to share
+layers while WFS uses GML, the Geography Markup Language. A third OGC
+interoperability specification is the Web Coverage Services specification or
+WCS--MapServer supports this at the server level only. To find more information
+about WMS, WFS, and WCS go the the `OGC's web site
+<http://www.opengeospatial.org>`_ and look for the `OGC Implementation
+Specifications <http://www.opengeospatial.org/specs/?page=specs>`_ or `OGC
+Abstract Specifications <http://www.opengeospatial.org/specs/?page=abstract>`_.
+The MapServer web site also has `documentation
+<http://mapserver.gis.umn.edu/doc.html>`_ and `WIKI pages
+<http://mapserver.gis.umn.edu/cgi-bin/wiki.pl>`_ for these specifications.
+
+This example shows you how to add a WMS layer in your mapfile.
+
+This is what the mapfile looks like: `Example1-7.map
+<http://biometry.gis.umn.edu/tutorial/example1-7.map>`_.
+
+Let's have a look at the WMS layer:
+
+**LAYER # MODIS WMS map from JPL**
+ Marks the start of the WMS LAYER object.
+
+**NAME modis_jpl**
+ The LAYER identifier.
+
+**TYPE RASTER**
+ Since this the WMS layer is an image, we use RASTER as LAYER TYPE.
+
+**OFFSITE 0 0 0**
+ Ignore the black background color
+
+**STATUS DEFAULT**
+ Turn this layer on by default.
+
+**CONNECTIONTYPE WMS**
+ The type of LAYER connection to use. The default is LOCAL--if we
+ have to be explicit, we would add CONNECTIONTYPE LOCAL to all othe
+ vector and raster layers in our mapfile. Instead we only define
+ connection types that are external. WMS is an external data layer,
+ coming from another map server.
+
+**CONNECTION "http://mapus.jpl.nasa.gov/wms.cgi?"**
+ The connection string that allows us to "get" the data
+ from another server. In the case of WMS connections, this is a URL.
+ If we were using a PostGIS database, it would be an SQL statement.
+ Please note that the string has to be in a single line in your
+ mapfile.
+
+**METADATA**
+ marks the beginning of the METADATA object for our WMS layer.
+ MapServer uses the parameters defined within this object along with
+ the CONNECTION parameter above to form a valid WMS request to the
+ WMS server.
+
+**"wms_srs" "epsg:4326"**
+ The WMS projection. Sometimes the WMS server supports more than one
+ projection. If this is the case you might want to request the map
+ in your output projection (epsg:2163). Unfortunately, the JPL
+ server doesn't support this projection.
+
+**"wms_name" "modis"**
+ The WMS layer name. This is like adding the parameter "layers=modis".
+
+**"wms_server_version" "1.1.1"**
+ The WMS version the server complies to. MapServer adheres to version
+ 1.1.1.
+
+**"wms_format" "image/jpeg"**
+ The image format we expect to be receiving from the WMS server. You
+ can try replacing the value with "image/png" or something
+ else.
+**END**
+ marks the end of the METADATA object
+
+To know more about adding WMS layers to your applications, please visit the `WMS
+Client HOW-TO document <http://mapserver.gis.umn.edu/doc/wms-client-howto.html>`_.
+
+In addition to adding the WMS layer object, there's also a new object under MAP. This is the WEB object. Within the WEB object are two parameters:
+
+**IMAGEPATH '/data/tmp/'**
+ The absolute local path to a web accessible temporary directory. The
+ user running the web server processes should be able to write to
+ this directory. Make sure that the path includes a slash (/) at the
+ end. (Your IMAGEPATH might look something like this:
+ "/home/apache/htdocs/tmp/" or
+ "C:/Inetpub/wwwroot/tmp/".)
+
+**IMAGEURL '/tmp/'**
+ This is how IMAGEPATH will appear relative to the web server's root
+ directory. If we have to type the full URL for this, it will be
+ "http://terrasip.gis.umn.edu/tmp/". Make sure that the
+ path includes a slash (/) at the end.
+
+ Finally, within the MAP object, I added a new parameter: NAME. This
+ is the identifier for the MAP object. MapServer uses this as prefix
+ to all images it creates and dumps to the "tmp" directory.
+ It's not needed at this point but it also doesn't hurt to have it.
+
+ If you would like to share your data layers to other map servers,
+ you will need to add METADATA objects within your MAP object and
+ within each of the LAYER objects you would like to share. All the
+ WMS layers that you added from another server will automatically be
+ cascaded and will also become available to others. To know more
+ about how to make your MapServer application become a WMS server,
+ please read the `WMS Server HOW-TO documentation
+ <http://mapserver.gis.umn.edu/doc/wms-server-howto.html>`_.
+ Documentations also exist for configuring MapServer application to
+ support the WFS standard, both as a `server
+ <http://mapserver.gis.umn.edu/doc/wfs-server-howto.html>`_ and as a
+ `client <http://mapserver.gis.umn.edu/doc/wfs-client-howto.html>`_.
\ No newline at end of file
More information about the mapserver-commits
mailing list