Ok, thanks to all, I finished my Reader Servlet. I created a work dir which has to be included into the webapps.policy so that webapps can read and write to it.
My reader servlet accepts a param "file" so far, since i haven't figured out how to do the mapping and parsing to do the /WebApp/files/filename.jpg so far. But that should be a quick fix. Anyhow, the path is stored in a context-param so all I need to do to port the application is set the path in the web.xml and set the policies to allow read/write access. And yes, i create subdirectories for each user and each picture will get a random file name. Since I maintain user objects which organize all the pictures each user uploads, it's no problem to find it again. Since this is only a test project for University, this stays in-memory, but apparenty, for a real deployment, the whole thing will be done with JDBC. But again, thanks for your help, recommendations and advices Robert
