I use Openlayers as a viewer of very large pictures, they are tiled and the navigation is exactly what I need.
I also can add a vector layer and draw on it.
But when it comes to save those drawings, saving them online... I can not find anything.
Then I learned about WFS-T and if a map (my picture) and its vector layer are on Geoserver it is possible for the user to draw on it and save the modifications to Geoserver.
Now I can not see how to upload a non georeferenced picture on Geoserver ? I got it up and running but that's it.
At this point I'm such a newbie I don't even know if my combo is the good solution to my problem : drawing with a vector layer on very large pictures and save online the modifications.