[mapserver-users] Adding a proxy/wrapper between the web frontend (openlayers) and mapserver

[Adrian Popa]

Hi everyone! I managed to create such a proxy/wrapper - after I 
generated the mapfile, I just modified some environment variables and 
called mapserv as a regular script. Thankfully the evrironment in which 
my wrapper was called is preserved and sent to mapserv.

Here's an example:

#create the mapfile as desired and save the contents to a file who's 
complete path is stored in $file

#change the query string and add the map parameter:
$ENV{'QUERY_STRING'} = $ENV{'QUERY_STRING'}."&map=$file";
#call the original mapserv script and return the output to the user
print `/var/www/cgi-bin/mapserv`;

#all done

The only major problem I encountered was that mapserver couldn't open 
the files referenced in the mapfile (fonts, template, shapefiles). I had 
to specify the  full paths in the map file to get it working.

Cheers,
Adrian

Adrian Popa wrote:
> Hello everyone!
>
> For special reasons (dynamic data) I need to create some sort of 
> proxy/wrapper around mapserv (5.2) to permit the dynamic modification 
> of the mapfile based on the age of the specific mapfile.
> Basically the user will request a mapfile which on most ocasions will 
> be generated on the fly (server-side). I would like to feed this 
> mapfile to mapserv and return the image to the user in a way it's 
> compatible with open layers. The user would see this wapper in a 
> transparent way.
>
> I know how to configure the openlayers part and I know how to generate 
> the map file, but I'm not sure how to link my wrapper to mapserver...
> How do I call mapserver the same way the web server would call it? I 
> think if I call it through a shell, it wouldn't work the same way. I 
> don't really want to call shp2img because it's harder to maintain.
>
> The output part should be straightforward - I would just print out 
> what mapserver returns - because it should take care of setting 
> content-type and sending the image.
>
> Any tips on where I could start?
> Thanks!
>
> P.S. I'm writing the wapper in perl and I'm not using the mapserver 
> API (but I could if it's necessary)
>
>
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