First of all, sorry for not replying to the original mail (i.e messing up the thread in the archive). I received it in a digest email, did not manage to figure out how to reply in a correct way. 

I tried with %u (updated the .desktop file, ran kbuildsycoca4). Same: the file is cached in /var/tmp/kdecache-barna/, and this file is given to my app. 
Thanks
On Thursday, 2012-03-08, Daniel Barna wrote:
Hi,

I have created a wrapper script around an application so that it can
handle remote files, and also directly save to the remote location (i.e.
immediately upload to the remote location when it saves the file)
The .desktop file contains this line:
Exec=my-application %U
indicating that this application can handle remote URLs. Nevertheless,
when I open a remote file in dolphin with my application, the remote
file is first downloaded to /var/tmp/kdecache-barna/... and this local
file is given to my application, instead of the original remote URL. Can
I change this behaviour somehow?
Hmm, you are right that %U should have the desired effect.
Can you try %u as well, i.e. indicating support for one URL?

Cheers,
Kevin