Have Geoportal's WMS requests in server or client?

Hello,

in the frame of security issues I came across the question what
the particular reasons are why geo-portals (MapBender, iGeoPortal, p.mapper etc)
do not execute WMS requests entirely on the client side (in JavaScript, like
OpenLayers does) but rather do it on the server side
(some do only GetCapabilities, some also GetMap).

The reasons I could imagine are:
* it was easier t o implement it this way
* with intensive JavaScript use we exclude some browsers.

I am extremely intersted if there are reasons beyond these
and would be thankful for any feedback.

All the best

	Jan

-- 
Dr. Jan-Oliver Wagner                        Intevation GmbH, Osnabrück
Amtsgericht Osnabrück, HR B 18998             http://www.intevation.de/
Geschäftsführer: Frank Koormann, Bernhard Reiter, Dr. Jan-Oliver Wagner