Direct changes in files on the owncloud server

Is it possible to make changes in user files direct on the server in a safe way?

I seek a way to safe to optimize very big files/picture direct on the server with a 3. party program, and to be sure that the new and improved file are synced out to the client. For example if a user have a camera that takes 20Mbit picture, then they are used direct in full size in the presentation (just resized in the program), that gives some very big files that can be reduced easy for 75% without it can be seen on screen and print.

I think something like:

1) Put the server in maintenance mode
2) Run the 3. party program on the data folder and subfolders.

3) Some command if exsits, that updates the database about the changed files.

4) Takes the server out of maintenance mode.
5) Changed files are synced to clients.

Is that possible? and Safe?


direct modifications within the datadir are unsupported and are known to cause various issues if you do such an unsupported operation:

Makes sense, seems like WebDAV access for the program is the way forward.

Is it possible to make/create a WebDAV connection that have access to all users folders?