WebSocket

What is the WebSocket API?

The WebSocket API is the next generation method of asynchronous communication from client to server. Communication takes place over single TCP socket using the(unsecure) or (secure) protocol and can be used by any client or server application. WebSocket is currently being standardized by the W3C. WebSocket is currently implemented in Firefox 4, Chrome 4, Opera 10.70, and Safari 5.

What's great about the WebSocket API that server and client can push messages to each other at any given time. WebSocket is not limited in its nature the way that AJAX (or XHR) is; AJAX technologies require a request to be made by the client, whereas WebSocket servers and clients can push each other messages. XHR is also limited by domain; the WebSocket API allows cross-domain messaging with no fuss.

AJAX technology was a clever usage of a feature not designed to be used the way it is today. WebSocket was created for the specific purpose of bi-direction message pushing.

WebSocket API Usage

Focusing on the client side API only (because each server side language will have its own API), the following snippet opens a connection, creates event listeners for connect, disconnect, and message events, sends a message back to the server, and closes the connection.

// Create a socket instancevar socket = new WebSocket('ws://localhost:…………………………………………………………………………
详细页面：http://www.verydemo.com/demo_c134_i11390.html