XML Mapfiles... are we looking to far?
hjulien at NRCAN.GC.CA
Thu Jul 20 09:57:23 EDT 2006
"Keep this in mind: every time someone creates a new XML language, God kills a kitten." (Sean)... good I hate cats but love dogs! :)
Well I didn't think I was going to start such a debate... if I get the general feeling right, I think people are interested in the concept but many have important reservations on the how and the why?
Tom, I used the OGC WMC as an example of distributed data. However in the case of Mapserver I propose to use an xml format that is very close to the current text format. Almost a one to one match! This will enable us to write an xsl stylesheet that can use the xml element names for the text mapfile output. This way the xml to text stylesheet will be easy to maintain in future modifications of the xml schema. Plus, such a one to one match will impose few modifications to Mapserver and users who are currently working with text mapfiles should rapidly catch on to the new xml format. Mapserver documentation wouldn't change much... we would just be adding xml "wellformedess" and the possibility to validate with a schema.
In an ideal world I agree that a more OGC like xml mapfile would be great but that would impose much more development and maintenance work either on the xsl side or on the main Mapserver application... furthermore is it an overkill to impose strict OGC specs for such a specific application use...?
"Sounds like this would be a worthwhile discussion in Lausanne "(Tom). We are always open to accepting travelling funds from Environment Canada! :)
I think I will continue working one the xml schema and xsl (after the Geoweb conference and 2 weeks of vacation)... then I'll try adding it to our Cocoon Mapserver wrapper to test it out. I will use the wrapper to fetch a database generated xml mapfile, transform it to text format with an xsl stylesheet and then output a locally saved text mapfile to feed Mapserver. Since mapfiles are not that big, I don't think speed will be an issue here.
If some of you are interested I can keep you informed and pass you on the xml schema and xsl. Eventually maybe some with much more programming skill then I will want to try implanting the xslt in Mapserver. :)
P.S. Tom, sorry for the "C" word again... BTW I debugged the Mapserver wms to kml service... it works great.
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