[mapserver-users] OpenGIS CITE

[Daniel Morissette]

Arnulf Christl (CCGIS) wrote:
> 
> The question we cannot answer is whether technically it makes sense to try
> and implement all of WFS into MapServer, what we do (believe to) know is
> that to use and support WFS does make very much sense. And we know that it
> is a lot to do and quite a lot of the details are irrelevant to most users
> but part of the spec. MapServer beeing *more permissive* than the spec
> allows is OK with us - but that for this reason it fails some tests is a
> problem that will have to be accounted for.
> 
> Another line of thought:
> There are other Free Software projects far on the way with WFS already. We
> cannot evaluate the need for UMN MapServer to be able to do WFS in all its
> details (and all on its own), but maybe it makes sense to just use whats
> already there.
> 
> We already use loads of other free software projects btw, we use free OS,
> free DB, free scripting lingos, free webserver. Would it make sense to use
> another free project for UMN MapServers WFS?
> 

Here are my 0.02$ on MapServer and WFS.  The comments below represent 
only my views and other may have different opinions that would be very 
valuable too I'm sure:

MapServer is a "map server", serving maps (GIF/PNG images, etc.) is what 
it's really good at and it's one of the best softwares for serving maps. 
  For this reason MapServer has to and will be made compliant with the 
WMS spec.  All the features of the WMS spec, including optional features 
should be supported by MapServer unless it really doesn't make sense to 
support a given feature.

WFS is about serving features (vectors and attributes), while this is 
very complementary to serving maps, it's not the same thing and is not 
what MapServer is best at.  It makes sense to provide 'basic' WFS 
capability in MapServer to complement web mapping applications, and we 
are currently working on enhancements to the WFS in MapServer to support 
filters (OGC filter encoding) which will make it a very useful WFS to 
query data.  However I don't think we should push MapServer to become a 
fully featured transactional WFS.

The above does not mean that MapServer users should be left on their own 
without a transactional WFS solution.  I already know of at least one 
open source package, GeoServer, that supports transactional WFS and 
there may be others.

Since we're in an open source world, there is no such thing as vendor 
locking, so we have no interest in preventing MapServer users from using 
GeoServer as well.  Actually, I have already talked with Markus Muller a 
few months ago about the possibility of sharing config files between 
MapServer, Degree and GeoServer.  Sharing a common config file format 
would allow someone to combine the best WMS and the best WFS on the same 
server with a single configuration file.

Looking at a Degree config file and comparing it to a MapServer map file 
it was not obvious how the mapping could be done (and I don't even know 
what the GeoServer config files look like or if they're the same).  The 
solution probably revolves around another OGC spec: Web Map Context 
documents (think of them as XML mapfiles for WMS layers only). One thing 
we could do is extend web map context documents to support local data 
sources (in addition to WMS layers), and then implement support for that 
extension in all three softwares.  This would require some work but 
should be quite feasible if developers from all three groups can find 
the time to sit and work on this together.

So in conclusion, I don't think we should push MapServer to become a 
fully features transactional WFS.  Instead, we should continue to put 
our efforts into making MapServer the best WMS around, and work with 
other groups who already have excellent WFS servers to build a bridge 
between MapServer and their software.

Daniel
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  Daniel Morissette               morissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
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