Add ability to read/write OGC context files from CGI

[sdlime]

At the moment OGC context files are only accessible via PHP MapScript. Those 
functions are in all version of MapScript though.

Steve

[dmorissette]

FYI for testing I had implemented a (undocumented) request=GetContext mapwms.c
that allows you to retrieve a context for a WMS-based mapfile with a call like:

http://your.server/cgi-bin/mapserv?map=...&SERVICE=WMS&REQUEST=GetContext&VERSION=1.0.0

The VERSION parameter controls the version of context document to return.

BTW, this request returns only the layers with CONNECTIONTYPE WMS at the moment,
but I've had requests from Tom Kralidis for a way to retrieve a context for a
mapfile in which all local layers are also exposed as WMS layers.  This would be
kind of bypassing GetCapabilities so I'm not sure if that's a good idea.

[dmorissette]

I have disabled the GetContext in the WMS CGI in 4.1 CVS because it could be
considered a security issue: it could publicly expose the URLs of WMS layers
used (cascaded) by a mapfile.

To re-enable it, set the "wms_getcontext_enabled" web metadata to "1" in your
WMS server's mapfile.

[tomkralidis]

Status on this one? Should we document this one -- in WMS Server or Map Context or both?

[tomkralidis]

bump...see comment:13

[dmorissette]

moving to Docs component. I'll let you (Tom) and Jeff sort out where that should go in docs.

[tomkralidis]

Suggest this be documented in Map Context howto only. Jeff: any comment?

[tomkralidis]

Documented in r8493.