i want to implement the possibility that people can comment on a picture, that is
displayed to them in the app. And that all other users can see the comments.
I was thinking about using a xml file in which the comments are put. And everytime
the app starts, this xml file is opened and the comments are displayed.
Would something like this work? Or is there a better possibility?
The other thing is, where to save this xml file? Could it be uploaded to skydrive / dropbox
from the app automatically?
You can save your xml in SkyDrive. Have a look at the Live SDK:
http://msdn.microsoft.com/en-us/live/ff621310
(Keep in mind if you share the file with a read & write hyperlink everyone who is able to view this link can read & edit your xml file.
Maybe you can create a Live-ID only for your App to get access to SkyDrive folders & files.)