Socket long link

What is? socket.socket Mainly used for instant messaging .socket It's a long connection .

Conventional http request , As the server returns a message to the client , The connection between the two disappears , So if the server wants to mainly contact the client, it has to rely on polling , But this kind of polling is more performance consuming , It consumes the performance of the client , And consumes server resources , So there is the concept of long connection .

Traditional type ：

Long link ：