nodejs socket close connection

Using Sockets for network communication in Node.js is a common practice and is often used to build network servers and client applications. However, during network communication, sometimes it is necessary to close the Socket connection. This article will introduce how to use Node.js to manage the closing of the Socket connection.

1. Reasons for closing the Socket connection

Closing the Socket connection means terminating the connection through the rules set up by both parties of the connection. This is a normal operation. The reasons why Socket closes the connection may be as follows:

1. Client closes the connection

When the client application no longer needs to communicate with the server, it can take the initiative Close the Socket connection. For example, when the user logs out or exits from the client application, or when the client application completes all tasks.

2. Server closes connection

When the server detects that a Socket connection is no longer needed, you can choose to close the connection. For example, when the server encounters a client that has not responded for a long time or finds that a connection is abnormal.

3. Socket transmission error

Socket is essentially a data stream based on the TCP/IP protocol. Like other network transmission methods, transmission errors may also occur when using Socket. Such as interruption or loss of connection. In this case, the Socket connection is also automatically closed.

2. Methods to close the Socket connection

In Node.js, you can use the following method to close the Socket connection:

1. end() method

end() method can be used to close the writing end. When the writing end of the Socket is closed, no more data is sent to the Socket, but the reading end can continue to receive data until it is also closed. When using the end() method, you can choose to pass in the last data block to be sent to ensure that the connection is closed after the data block is sent.

For example:

const net = require('net');

const server = net.createServer((socket) => {
  // 处理连接
  // ...

  // 关闭写入端
  socket.end('Goodbye
');
});

server.listen(8080);

When the client receives "Goodbye", the connection will be automatically closed.

2. destroy() method

Thedestroy() method can be used to close the Socket connection immediately, regardless of the current transmission status. When the Socket connection is quickly closed, neither the writer nor the reader can perform any further transmission operations. When using the destroy() method, you need to pay attention to the current Socket status and transmission data to avoid data transmission interruption or incomplete data transmission.

For example:

const net = require('net');

const server = net.createServer((socket) => {
  // 处理连接
  // ...

  // 销毁连接
  socket.destroy();
});

server.listen(8080);

When using the destroy() method, since errors may occur during the transmission process, an error handler needs to be added.

const net = require('net');

const server = net.createServer((socket) => {
  // 处理连接
  // ...

  // 销毁连接
  socket.destroy();

  socket.on('error', (err) => {
    console.log(`Socket 错误：${err}`);
  });
});

server.listen(8080);

In addition, another common Socket closing method is to use the destroySoon() method. This method is similar to the end() method, but it will close the connection immediately instead of waiting until the remaining data is sent. However, since this method is not always reliable, it is recommended to use the end() or destroy() method whenever possible.

3. Summary

Socket closing the connection is an essential part of network communication. In Node.js, you can use the end() and destroy() methods to close the connection. When using it, you need to pay attention to the current Socket status and the data blocks being transmitted to avoid connection interruption or data loss. At the same time, when closing the connection, an error handler needs to be added to detect and handle errors in time.

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