Multi Platform Chat Application & Back End

This project is to create a multi-platform chat application, including the server back end supporting: - Windows (desktop and Windows 8 mobile) - iOS (iPhone, iPad) - Mac OS X - Linux - Android This should be a full featured chat similar to Yahoo Chat, Windows Messenger, KIK, etc. and should allow for the user to: - Create a profile with several fields / profile picture - Send/receive photos in messages - Search member directory - Privacy options (don't list in directory, block specific users) - Built-in emoticons - Group chat (i.e. more two users chatting with each other) Users should be able to communicate with each other regardless of which platform they are running the client on. Server back end should handle registrations and routing of messages. This can run on any platform but should be scalable as number of users increases (should support some kind of dedicated server architecture that one would rent from a hosting company).