I already published an android app where you can see a list of specific objects and detailed informations about them. The list changes every day but some of the objects can appear again. The application is communicating with a PHP server over HTTP and periodically pulls the list of objects.
I now plan to extend the app to make it possible to rate the objects and add a comment similar to how it is done in the android market. I'd like to avoid forcing the user to sign up for an account for being able to comment.
I see two problems:
- The comment-system could be abused by spammers
- A comment could be added from another system
So my questions are:
- How to protect the system from spam?
- How to authenticate the application with the server?
- How do I limit the number of comments to one per user and object?
- What about the androids device id? Is it unique enough to use it as identifier for the user?
- Which other problems do you see?