I am building a Messaging Application Exactly Like WhatsApp, The Technologies I have used are Socket.io, FCM, Node.js, MongoDB. Until now I have achieved Chatting and Notification functionality But now I am struck very badly for two things :
- Syncing Contacts With The MongoDB and Only save the users available to the local DB (I know about SyncAdapters But it's been months finding the algorithm for doing it the most efficient way)
- If Any of the contacts update the profile picture how will it notify all the contacts excluding the ones who haven't saved the number. (Eg User A updates The profile pic and has User B number saved but User B is not having User A number Then User A should not send any updates to User B)