As mentioned earlier, websocket has some client frameworks to simplify programming. Today, we use socket. Io and node. js to write a helloworld websocket communication.
One of them is socket. io, socket. io belongs to node. JS (nodejs is a server-side Programming Technology JavaScript) module, node. JS can use socket. the I/O Library easily implements the websocket function.
Several knowledge points to be aware:
Javascript can be used as a language for server-side programming. The typical case is node. js.
Node. js uses event-driven, asynchronous programming to design http://baike.baidu.com/view/3974030.htm for Network Services
Node. js needs to execute the service environment, can download on the official website, I use http://nodejs.org support window
Run the command: node XXX. js will execute the XXX. js script.
Socket. Io official website http://socket.io/and node. js with the use
The socket. Io module is not included in node. js. Therefore, to install it, run the NPM install socket. Io command. If a module cannot be found during running, use this command to install it.
Node. js's first helloworld
1. Write a JS file helloworld. js
VaR HTTP = require ('http ');
HTTP. createserver (function (req, Res ){
Res. writehead (200, {'content-type': 'text/plain '});
Res. End ('Hello world \ n ');
}
). Listen (8080, '192. 0.0.1 ');
Console. Log ('server running at http: // 127.0.0.1: 8080 /');
2. Run the node helloworld. js command under the JS directory in the CMD script.
The message "server running at http: // 127.0.0.1: 8080/" is printed/
3. Enter http: // 127.0.0.1: 8080 in the browser. The helloworld page is displayed.
The first example of using Socket. Io to implement the websocket Function
1. Write a helloworld.html File
<! Doctype HTML public "-// W3C // dtd html 4.01 transitional // en" "http://www.w3.org/TR/html4/loose.dtd">
<HTML>
<Head>
<Title> new document </title>
<Meta name = "generator" content = "editplus">
<Meta name = "author" content = "">
<Meta name = "keywords" content = "">
<Meta name = "Description" content = "">
</Head>
<SCRIPT src = "/socket. IO/socket. Io. js"> </SCRIPT> <! -- Obtain socket. Io. js from the server as long as your server has installed the socket. Io module. -->
<SCRIPT>
VaR socket = Io. Connect ('ws: // 127.0.0.1/'); // establish a connection to the server
Socket. emit ('client', 'Hello world! '); // Send data to the server. on the server side, you can receive data whose name is client.
Socket. On ('server', function (data) {// receives data from the server named Server
Alert (data );
});
</SCRIPT>
<Body>
</Body>
</Html>
2. Write a script helloworld_server.js next to it.
VaR Server = require ('HTTP '). createserver (handler); // use handler to process requests
VaR IO = require ('socket. Io '). Listen (server); // socket. Io object
VaR FS = require ('fs'); // The object used to operate the file
Server. Listen (80); // listen to port 80 of the Local Machine
// Function used to process the request
Function handler (req, Res) {// req indicates the request object res indicates the response object
// Nvidirnameis the application root directory, which reads the helloworld.html file in the root directory and sends the response
FS. readfile (_ dirname + '/helloworld.html ',
Function (ERR, data ){
If (ERR ){
// If an exception occurs, send an error message to the client.
Res. writehead (500 );
Return res. End ('error loading index.html ');
}
Res. writehead (200 );
Res. End (data); // send the content in the file and end the response.
});
}
// Listener
Io. sockets. On ('connection', function (socket ){
Console. Log ('Connection success ');
// Receive data from the client named Client
Socket. On ('client', function (data ){
Console. Log ('Received message from client: '+ data );
Socket. emit ('server', 'I have Ed you message:' + data); // send data named server to the client
});
});
3. Start the server: node helloworld_server.js
4. Enter http: // 127.0.0.1 in the browser
The browser will send a message to the server, and the server will reply a message to the browser.
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