如何在Twitter中实现实时通知？

Question

How twitter page queries/receives notifications, information about new tweets? I'd like to implement something like this mechanism for my html+js client->webservice

Answer 1

I don't know what Twitter uses exactly but there are few techniques to handle server notifications. You can use long-polling (your client issues the same ajax request every few seconds to get new information): http://techoctave.com/c7/posts/60-simple-long-polling-example-with-javascript-and-jquery/

Or there is the "new" standard called Websocket . A good start to how to write a websocket client is this mozilla tutorial .

Answer 2

There are multiple ways to implement real-time notifications:

• HTTP Long Polling : The client initiates a request. The server checks if it has any new notifications. Irrespective of whether or not it has new notifications appropriate response is send and connection is closed. After time X client initiates another request (+ Very easy to implement - notifications are not real time. They depend on X since data retrieval is client initiated. As X decreases overhead on server increases )

• HTTP Streaming: This is very similar to HTTP Long Polling however the connection is not closed. The server sends chunked response. So as soon as server receives new notification that it wants to push it can simply write to the socket. ( + lower latency than long polling and almost real time behaviour / overhead of closing connection and re opening reduced - memory usage client side keeps on piling up / ugly hacks etc )

• WebSocket: TCP based protocol provides true two way communication. The server can push data to client any time. ( + ve: true real time - some older browsers dont support it ). Read more about it WebSocket.org | About WebSocket