The difference and connection between WebSocket and long connection

The difference and connection between WebSocket and long connections

With the continuous development of Internet technology, web applications are increasingly using real-time communication to provide better users experience. In the process of realizing real-time communication, the concepts of WebSocket and long connection are often involved.

Both WebSocket and long connections can be used to achieve real-time communication, but they have some differences and connections.

Difference:

1. Technical principle:

   • WebSocket: Handshake upgrade mechanism based on HTTP protocol, full duplex through a TCP connection communication. After the handshake connection is established, the communication between the client and the server no longer relies on HTTP requests, but can send and receive data directly through this TCP connection.
   • Long connection: The HTTP protocol itself is stateless, and each request and response are independent. A long connection establishes a persistent connection between the client and the server to maintain data transmission for a period of time.

2. Communication method:

   • WebSocket: Provides full-duplex communication capabilities. The server can actively push data to the client, and the client can also Send a request to the server. This enables real-time communication and eliminates the need for polling or frequent requests to obtain new data.
   • Long connection: Generally, the client initiates a connection request, the server maintains the request, and regularly sends heartbeat packets to maintain the connection. When there is data to be transmitted, the server can send data directly to the client.

3. Applicable scenarios:

   • WebSocket: suitable for real-time data transmission and real-time communication scenarios, such as online chat, stock quotes, real-time games, etc. .
   • Long connection: Suitable for scenarios that require real-time notifications or instant status updates, such as push services, message push, online monitoring, etc.

Contact:

1. The underlying protocol used:

   • WebSocket: based on TCP protocol, implemented One-to-one, two-way communication.
   • Long connection: It is also based on the TCP protocol and adopts a mechanism to maintain the connection for a long time.

2. Implementation method:

   • WebSocket: The corresponding protocol and event processing logic need to be implemented on the client and server respectively.
   • Long connection: The connection needs to be maintained on the server side and the received data must be processed on the client side.

The following is a simple sample code that demonstrates the implementation of WebSocket and long connections.

WebSocket sample code:

// Client code
var ws = new WebSocket("ws://127.0.0.1:8080");
ws.onopen = function() {
ws.send("Hello Server!");
};
ws.onmessage = function(event) {
var message = event.data;
console. log("Receive Message: " message);
};
ws.onclose = function() {
console.log("Connection closed");
};

// Server-side code (using Node.js example)
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss .on('connection', function connection(ws) {
ws.on('message', function incoming(message) {

  console.log('received: %s', message);
  ws.send('Server received: ' + message);

});
ws.on('close' , function close() {

  console.log('disconnected');

});
});

Long connection example code:

//Client code
var conn = new WebSocket("ws://127.0.0.1:8080");
conn.onmessage = function(event) {
var message = event.data;
console.log("Receive Message: " message);
};
conn.onclose = function() {
console.log("Connection closed");
};

// Server-side code (using Node.js example)
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', function connection(ws) {
setInterval(function() {

  ws.send("Server message");

}, 1000);
ws.on('close', function close() {

  console.log('disconnected');

});
});

Through the above sample code, we can see how to use WebSocket and long connections. WebSocket establishes a full-duplex communication connection through the handshake upgrade mechanism, which can achieve real-time communication; while long connections achieve real-time data transmission by maintaining the connection. Both can meet the needs of real-time communication, and the appropriate solution can be selected according to specific scenarios to realize the real-time nature of Internet applications.

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