Introduction to socket.io learning tutorial in node.js (1)

socket.io provides real-time two-way communication based on events, so the following article mainly introduces relevant information about socket.io, and mainly introduces the basic knowledge of learning socket.io. Friends who need it can refer to it. Below Let’s take a look together.

Preface

Real-time data transmission between the Web client and the server is a very important requirement, but at the earliest it can only be passed AJAX polling implementation. Before the WebSocket standard was introduced, AJAX polling was the only feasible way (it was also possible through the Flash browser, but we will not discuss it here). The principle of AJAX polling is to set a timer to synchronize server data through AJAX at regular intervals. This method involves delays and places a heavy load on the server. It wasn't until 2011 that the IETF standardized WebSocket, a protocol for sending and receiving data based on TCP sockets. Nowadays, all major browsers support WebSocket.

socket.io separates the data transmission part to form engine.io. Engine.io encapsulates WebSocket and AJAX polling to form a set of APIs. It shields detail differences and compatibility issues, and realizes cross-browser/cross-device bidirectional data.

socket.io is not necessary for engine.io. You can also implement your own engine.io and bind it through server.bind

Application

• Real-time data analysis display (reports, logs)

• Instant messaging, chat,

• Binary stream (picture, music, video) transmission

• Multi-person collaborative editing

• Instant Message push
  

Similar technology

• AJAX polling: AJAX polling based on XMLHttpRequest

• AJAX long polling: Similar to polling, the server does not return a response after the client requests it until there is data that needs to be transmitted to the client. After the data is transmitted The client initiates a new request. The disadvantage is that additional HTTP headers need to be transmitted, and it also requires some extra work to keep the request from responding.

• HTTP stream: Similar to AJAX long polling, the server response will bring the HTTP header: Transfer-Encoding: chunked, after returning the data to the client The client does not need to initiate a new request. The disadvantage is that the data between each chunk is difficult to identify and process.

• Plug-ins: Similar to Flash and Silverlight, as plug-ins are increasingly rejected by mainstream browsers and users
  

Here are the different angles Analyze each technology

• One-way/two-way

• One-way: AJAX polling, AJAX long polling, HTTP streaming

• Two-way: WebSocket, Plug-in

• Delay
  

##WebSocket < Plug-in< HTTP Stream< AJAX Long Polling< AJAX Polling

1. Efficiency

Plug-in> WebSocket > HTTP Streaming> AJAX Long Polling> AJAX Polling

1. Mobile terminal support

WebSocket: basically supports

HTTP stream, AJAX long polling, AJAX polling: basically supports

Plug-in: Basically not supported

1. Ease of development or setup

WebSocket < AJAX Polling< Plug-in< AJAX Long Polling , HTTP stream

Summary

socket.io encapsulates WebSocket. If WebSocket is not supported, it also provides downgraded AJAX polling, which is fully functional. , elegantly designed, is the perfect way to develop real-time two-way communications.

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