The specific requirements are as follows:
Realize the function of real-time notification between users.
That is, user A will send a real-time notification to user B if it triggers an event. (if user b is online)
Most demo on the internet are session-based and do not exist after refreshing or closing.
If a user connection already exists, what should I do?
Just give me some ideas
First of all, the messages of A->B should be sent through the server and marked unread at the same time. if user b is online, then user b will send a request to mark the received message as read, that is, received. When the time comes for user b to go online, just pull down his unread message.