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1. Use the net module to implement TCP-based data communication
Provides a net module dedicated to realizing communication between the TCP server and the TCP client
1.1 Create a TCP server
Use the net module to create a TCP server in Node.js
var server = net.createServer([options],[connectionListener]) //options:false当TCP服务器接收到客户端发送的一个FIN包时将会回发一个FIN包 true当TCP服务器接收到客户端发送的一个FIN包时将不会回发FIN包,这使得TCP服务器可以继续向客户端发送数据,但不会继续接收客户端发送的数据。来发者必须调用end方法来关闭socket连接。默认为false connectionListener:指定当客户端与服务器端简历连接时所要调用的回调函数 function(socket){ //回调函数代码 }
The parameter value is the socket port object that the TCP server listens to. The createServer method returns the created TCP server
When the client establishes a connection with the server, the connection event is triggered. You can use the following method to execute the callback function
server.on('connection',function(socket){ //回调函数代码 })
After creating the TCP server, use the listen method to notify the server to start monitoring the client connection
server.listen(port,[host],[backlog],[callback]) //port指定需要监听的端口号, host:指定需要监听的IP地址或主机名,如果省略,服务器将监听来自于任何IPv4地址的客户端连接 backlog:指定位于等待队列中的客户端连接的最大数量 callback:无参回调函数 server.listen(path,[callback]) //server:代表一个使用unix端口的服务器 path:指定需要监听的路径,会触发listening事件,然后执行回调函数callback server.listenting(handle,[callback]) //server 代表一个TCP服务器 handle:指定需要监听的socket句柄(该句柄可以为一个TCP服务器对象,socket端口对象,文件描述符)
Here is an example to create a TCP server:
var net = require('net') var server = net.createServer(function(socket){ console.log('客户端与服务器连接已建立') }) server.listen(8431,'localhost',function(){ console.log('服务器端开始监听') })
After running, you can get the following results:
Use telnet to access the corresponding server:
telnet localhost 8431
The results that will appear are as follows:
socket port object example:
var net = require('net') var file = require('fs').createWriteStream('./message.txt'); var server = net.createServer(function(socket){ console.log('客户端与服务器连接已建立') server.getConnections(function(err,count){ console.log('当前存在%d个客户端连接。',count); server.maxConnections = 4; console.log('TCP服务器的最大连接数为%d',server.maxConnections); }) // server.close(function(){ // console.log('TCP服务器被关闭。'); // }) }) server.listen(8431,'localhost',function(){ console.log('服务器端开始监听') }) server.on('connection',function(socket){ address = socket.address(); console.log('被监视的地址信息为%j',address); socket.pipe(file); socket.setEncoding('utf8'); socket.on('data',function(data){ console.log(data.toString()); console.log('已接受到%d字节数据。',socket.bytesRead); }); socket.on('end',function(){ file.end('再见') console.log('客户端连接被关闭。') }) socket.pause(); setTimeout(function(){ console.log('*************') socket.resume(); socket.pipe(file,{end:false}); },30*1000); // socket.pipe(file,{end:false}); // setTimeout(function(){ // file.end('再见。'); // socket.unpipe(file); // },5000); socket.setTimeout(10*1000); socket.on('timeout',function(){ console.log('客户端连接超时'); socket.setTimeout(0); }) })
1.2 Create TCP client
Establish TCP client example:
var net = require("net"); var client = new net.Socket(); client.setEncoding('utf8'); client.connect(8431,'localhost',function(){ console.log('已连接到服务器'); client.write('你好'); console.log('当前已发送%d字节',client.bytesWritten); client.end('再见') console.log('当前已发送%d字节',client.bytesWritten); // setTimeout(function(){ // client.end('再见'); // },10*1000) }); client.on('data',function(data){ //console.log('已接收服务器端发送的数据: '+data); console.log('已接收服务器端发送的数据'); }) client.on('error',function(err){ console.log('与服务器连接或通信的过程中发生了一个错误,错误编码为%s',err.code); client.destroy(); })
At the same time, the corresponding server needs to be established:
var net = require('net'); var fs = require('fs'); var server = net.createServer(); server.on('connection',function(socket){ console.log('客户端与服务器端连接已建立'); socket.setEncoding('utf8'); var readStream = fs.createReadStream('./server.js'); readStream.on('data',function(data){ var flag = socket.write(data); console.log('write方法的返回值为:'+flag); console.log('缓存队列中当前缓存了%d字符。',socket.bufferSize); }) socket.on('data',function(data){ console.log('已连接客户端发送的数据:'+data); socket.write('确认数据:'+data); }) socket.on('error',function(err){ console.log('客户端通信的过程中发生了一个错误,错误编码为%s',err.code); socket.destroy(); }) socket.on('end',function(){ console.log('客户端连接被关闭。'); server.unref(); }) socket.on('close',function(had_error){ if(had_error){ console.log('由于一个错误导致socket端口被关闭。'); server.unref(); }else{ console.log('socket端口被正常关闭。'); } }) server.getConnections(function(err,count){ if(count==2) server.close(); }); }); server.listen(8431,'localhost'); server.on('close',function(){ console.log('TCP服务器被关闭。'); })
In Node.js, the following method can be used to continuously send detection packets to the client or server to determine the connection status;
socket.setKeepAlive([enable],[initialDelay]) //enable:true:启用Keep-alive机制,不断向对方发送一个探测包,如果没有回应表示连接关闭 initialDelay:间隔时间(毫秒)
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Node.js creates Web and TCP servers
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What is the difference between TCP/IP and UDP
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