WebSockets

It is two way ( full-duplex - in both direction at same time ) communication protocol between server & client using long running TCP connection.  Client  & server both  can send messages to one another in asynchronous manner.  The messages are sent with very little overhead and hence results in very low latency.

Websockets remove the need for long polling in the HTTP based applications needing real time updates from server.  Long-polling is done so that client application does not have to keep polling/requesting  server for updates as it results in  frequent HTTP connection overheads.  So client makes a request and server waits as long as it can, until either there is update for client or it times out. This is called long polling. 


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