PNews jun 2015 - Page 17

Tutorials Point, Simply Easy Learning HTML5 – WebSockets Web Sockets is a next-generation bidirectional communication technology for web applications which operates over a single socket and is exposed via a JavaScript interface in HTML 5 compliant browsers. Once you get a Web Socket connection with the web server, you can send data from browser to server by calling a send() method, and receive data from server to browser by an onmessage event handler. Following is the API which creates a new WebSocket object. var Socket = new WebSocket(url, [protocal] ); Here first argument, url, specifies the URL to which to connect. The second attribute, protocol is optional, and if present, specifies a sub-protocol that the server must support for the connection to be successful. WebSocket Attributes: Following are the attribute of WebSocket object. Assuming we created Socket object as mentioned above: Attribute Socket.readyState Description The readonly attribute readyState represents the state of the connection. It can have the following values: 1. 2. 3. 4. Socket.bufferedAmount WebSocket Events: 17 | P a g e A value of 0 indicates that the connection has not yet been established. A value of 1 indicates that the connection is established and communication is possible. A value of 2 indicates that the connection is going through the closing handshake. A value of 3 indicates that the connection has been closed or could not be opened. The readonly attribute bufferedAmount represents the number of bytes of UTF-8 text that have been queued using send() method.