HTTP Long Polling

In Nutshell

HTTP Long Polling is a technique used to push information to a client as soon as possible on the server. Server does not have to wait for client to send request

Visualize Long poll

Key points

Server never close connection once it revies request from client
It responds only when new message is available or gets timeout when threshold is reached
Once the client receives a response, it immediately sends a new request to the server and process is repeated.

This helps server mirror a Realtime Server Push feature

For more details : please visit here