Long Polling

The long-polling technique is a combination of server-push and client-pull because the client needs to resume the connection after a certain amount of time or after the server pushes an update to the client.

The basic life cycle of an application using long-polling is:

request -> suspend --> data available --> write response --> resume

The client makes an initial request and then suspends the request. When an update is available, the server writes it to the response. The connection closes, and the client optionally resumes the connection.