Getting started with socket. io in node. js _ javascript class library

This article mainly introduces the socket. io entry instance in node. js, and introduces reverse ajax technologies such as websocket. For more information, see Introduction to websocket and other Reverse ajax Technologies

In real-time web applications, a common method is reverse Ajax. Definition of reverse Ajax:

Reverse Ajax (Reverse Ajax) is essentially a concept that can send data from the server to the client. In a standard HTTP Ajax request, data is sent to the server. Reverse Ajax can simulate an Ajax request in some specific ways, which will be discussed in this article, the server can send events (low-latency communication) to the client as quickly as possible ).

The reverse Ajax technology has two main aspects: first, the server maintains a TCP connection until it has data sent to the client (loop and sleep can be used), and second, the client js programming skills.

Websocket is an html5 standard and also an anti-ajax technology.

Socket. io reverse AJAX technology example

Socket. io official introduction:

Socket. IO aims to make realtime apps possible in every browser and mobile device, blurring the differences between the different transport mechanisms. it's care-free realtime 100% in JavaScript. in order to provide realtime connectivity on every browser, Socket. IO selects the most capable transport at runtime, without it affecting the API. webSocket Adobe®Flash®Socket AJAX long polling AJAX multipart streaming Forever Iframe JSONP Polling

Simply put, socket. io is a node. js-based library that encapsulates multiple reverse ajax technologies and unifies interfaces. During running, socket. io automatically selects the appropriate reverse ajax technology based on the browser's situation to interact with the socket. io server. If websocket and other technologies are standardized, socket. io belongs to the application.

The following describes how to install it (the author uses Linux Mint 16 ):

Install node. js:

The Code is as follows:

Sudo apt-get install nodejs

Enter the command nodejs to enter the shell mode.

Install npm:

The Code is as follows:

Sudo apt-get install npm

Install socket. io:

The Code is as follows:

Sudo npm install socket. io

The installation package is stored in ~ /Node_modules directory, the client socket. io. js is stored in ~ /Node_modules/socket. io/node_modules/socket. io-client/dist directory.

Socket. io example

The following example is from the official website and is modified as appropriate.

First, create the server (server) code (file test. js ):

The Code is as follows:

Var io = require ('socket. io '). listen (8080 );

Io. sockets. on ('connection', function (socket ){
Socket. emit ('new', {hello: 'World '});
Socket. on ('My other event', function (data ){
Console. log (data );
});
});

Server test. js binds port 8080. When a client connects to the server test. in js, the server test. js sends the news command to the client and transmits the data {hello: 'World'}, while the server test. when js receives the my other event command, it will call the callback function (data) {console. log (data) ;}to process the received data.

I set up the nginx server, which uses port 80 and the web root directory is/usr/share/nginx/html. Change ~ /Node_modules/socket. io/node_modules/socket. socket under io-client/dist. io. min. copy js to the web root directory, and create the file index under the web root directory. php (as the client), the content is as follows:

The Code is as follows: