[mapserver-users] WFS support

[Daniel Morissette]

Juanse wrote:
> 
> Sorry to bother, but can you explaime in brief what WFS stand for; and what
> does it does or is different than WMS (Web map server?).
> 


WFS stands for Web Feature Service.

The difference with WMS is that WMS returns an image (GIF, PNG) of
selected layers, and WFS returns vector features encoded in GML format. 
GML stands for Geography Markup Language and is an XML encoding of
vector feature information (attributes and coordinates information).

When you're browsing maps, zooming, etc then you want to use a WMS
server, it's still the most efficient way to browse maps built from
remote data sources.  However since a WMS sends you only a raster image
of the data then it's not possible to do anything intelligent with it
like performing attribute queries, or other operations that you would
normally do on vector data such as buffers, etc.

That's where WFS becomes useful... it allows you to connect to a remote
server to request features that match some attribute filter expression
for the area of your map, and then your client app (or a cascading
server) can use the feature information just like if it was coming out
of a local shapefile or a connection to PostGIS or another GIS database.

This is in no way a complete description of WFS and of everything you
can do with it, but I hope that will help you (and others on the list)
understand the difference.

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