enhance MapServer’s ability to read Map Context files in cgi mode.

[assefa]

General Notes: Map context contains layer information that can be used to 
request WMS layers. Compared to the traditional Mapserver’s map files, they 
miss some crucial configuration parameters like the imagepath or imageurl that 
Mapserver used to store temporarily images created. To be able to smoothly run 
a Mapserver cgi application with a Map Context, the application administrator 
need to provide a default map file with at least the basic required parameters 
that will be used with the Conext file.  This default map file can contain as 
little information as the imagepath and imageurl or contain a list of layers. 
Information coming from the context (e.g.: layers, width, height, 
) would 
either be appended or replace values found  in the map file.


1.	Add support to local Map Context files

·	Define a new cgi parameter called context that will be used to specify 
a local context file. The user can then use Mapserver to request for example a 
map using the following syntax: http://localhost/mapserver.cgi?
mode=map&map=/path/to/mapfile.map&context=/path/to/contextfile.xml


2.	Add support to context files accessed through a URL

·	The syntax of using the web accessible context file would be similar 
to accessing local context file (http://localhost/mapserver.cgi?
mode=map&map=/path/to/mapfile.map&context=http:://URL/path/to/contextfile.xml..

·	Security concerns: since loading a file from a URL is associated with 
security issues, the default behavior of Mapserver will be to restrict this 
possibility. To be able to have this functionality, what we propose is to have 
a setting (in form of a CONFIG parameter) in the default map file that will 
allow this functionality.

[assefa]

Code done. Formal QA to be done. Doc missing.

Jeff : I am going to provide you with a text explaining the support. It
needs to be added in the mapserver docs.

[assefa]

QA done by Norm.

I have sent a quick howto to Jeff for review and integration in the mapserver docs.

Assigning the bug to Jeff

[jmckenna@…]

accepting..

[jmckenna@…]

moving to documentation Component

[jmckenna@…]

moving to documentation Component

[jmckenna@…]

this was already added into the Map Context doc.  must have forgotten to close bug.