net.createServer([options][, connectionListener])

Creates a new TCP or IPC server. 创建一个新的TCP或IPC服务。

• options <Object>   allowHalfOpen <boolean> 表示是否允许一个半开的TCP连接。 默认值: false   pauseOnConnect <boolean> 一旦来了连接，是否暂停套接字。 默认值: false
• connectionListener <Function> 为'connection' 事件自动设置一个监听器。
• 返回: <net.Server>

如果 allowHalfOpen 被设置为true, 那么当socket.end() 被显式调用时, 如果对边套接字发送了一个FIN包，服务只会返回一个FIN数据包， 这会持续到后来连接处在半闭状态 (不可读但是可写)。 请查看'end' 事件和 RFC 1122 (4.2.2.13节) 获取更多信息。

如果 pauseOnConnect 被设置为 true, 那么与连接相关的套接字都会暂停，也不会从套接字句柄读取数据。 这样就允许连接在进程之间传递，避免数据被最初的进程读取。 如果想从一个暂停的套接字开始读数据，请调用socket.resume()

服务可以是一个TCP服务或者一个 IPC 服务, 这取决于listen() 监听什么

这是一个简单的TCP回声服务器在8124端口上监听连接的例子：

const net = require('net');
const server = net.createServer((c) => {
  // 'connection' listener
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
  c.write('hello\r\n');
  c.pipe(c);
});
server.on('error', (err) => {
  throw err;
});
server.listen(8124, () => {
  console.log('server bound');
});

用 telnet测试:

$ telnet localhost 8124

想监听 /tmp/echo.sock 只需改最后三行为：

server.listen('/tmp/echo.sock', () => {
  console.log('server bound');
});

用 nc 连一个 UNIX 域套接字服务器:

$ nc -U /tmp/echo.sock

• options <Object>

  • allowHalfOpen <boolean> Indicates whether half-opened TCP connections are allowed. Default: false.
  • pauseOnConnect <boolean> Indicates whether the socket should be paused on incoming connections. Default: false.
• connectionListener <Function> Automatically set as a listener for the 'connection' event.
• Returns: <net.Server>

Creates a new TCP or IPC server.

If allowHalfOpen is set to true, when the other end of the socket sends a FIN packet, the server will only send a FIN packet back when socket.end() is explicitly called, until then the connection is half-closed (non-readable but still writable). See 'end' event and RFC 1122 (section 4.2.2.13) for more information.

If pauseOnConnect is set to true, then the socket associated with each incoming connection will be paused, and no data will be read from its handle. This allows connections to be passed between processes without any data being read by the original process. To begin reading data from a paused socket, call socket.resume().

The server can be a TCP server or an IPC server, depending on what it listen() to.

Here is an example of an TCP echo server which listens for connections on port 8124:

const net = require('net');
const server = net.createServer((c) => {
  // 'connection' listener
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
  c.write('hello\r\n');
  c.pipe(c);
});
server.on('error', (err) => {
  throw err;
});
server.listen(8124, () => {
  console.log('server bound');
});

Test this by using telnet:

$ telnet localhost 8124

To listen on the socket /tmp/echo.sock the third line from the last would just be changed to:

server.listen('/tmp/echo.sock', () => {
  console.log('server bound');
});

Use nc to connect to a UNIX domain socket server:

$ nc -U /tmp/echo.sock