title: Sending data to an offline/inactive app
body: <p>I want to create a mobile chat/message application. There will be online and offline users. I want users to be able to send messages to online AND offline users.If two users are online I will use websockets for them to talk, but I am running into problems if an online user wants to send an offline user a message. If an online user sends an offline user a message I would like the sender to know if the message was delivered or not. Is this possible? I know I can use push notifications to send the offline user that a new message has arrived, but I can't find anything about sending the message to the offline user while the app is still not running. Do I have to store the message in a database and then when the receiver opens his app send them the new message or is there another way?</p>