HTML5的TCP和UDP Web Socket API草案定稿

這是在 Web 上實現 UDP/TCP API 的草案，沿未形成標準。該標準的一大亮點就是使用內置 Promise 設計模式，替代了傳統 JavaScript 中的事件觸發回調。不過各大瀏覽器廠商會不會這樣實現還要打一個問號，畢竟編寫標準的學院派和實現標準的行業派很難達到完全統一。

　　以下內容來自： http://www.w3.org/TR/2014/WD-tcp-udp-sockets-20141202/

　　接口標準提供對原始 UDP 套接字(Socket)，TCP 客戶端套接字和 TCP 服務器套接字 API 的定義。

　　簡介

　　這部分沿未形成規范。您可以使用該 API 來發送和接收數據，并使用 TCP 或 UDP 網絡。

　　使用此 API 的部分用例：

• 能夠與 SMTP, POP3 和 IMAP 服務器進行通信的郵件服務器。
• 一個能與 IRC 服務器進行通信的 IRC 客戶端 （注* IRC 是一種通過網絡的即時聊天方式。其主要用于群組聊天。）
• 實現一個 SSH 應用程序
• 與現有的消費硬件產品進行通信，如互聯網電視
• 游戲服務器
• 端到端應用程序（注* P2P 或對等網絡應用）
• 本地網絡多播服務（multicast service）發掘，例如 UPnP/ SSDP 和 mDNS

　　一個 UDP 的例子：

 // // This example shows a simple implementation of UPnP-SSDP M-SEARCH
// discovery using a multicast UDPSocket 
//
 var address = '239.255.255.250',
    port = '1900',
    serviceType = 'upnp:rootdevice',
    rn = '\r\n',
    search = '';

//  Create a new UDP client socket var mySocket = new UDPSocket ();

// Build an SSDP M-SEARCH multicast message search += 'M-SEARCH * HTTP/1.1' + rn;
search += 'ST: ' + serviceType + rn;
search += 'MAN: "ssdp:discover"' + rn;
search += 'HOST: ' + address + ':' + port + rn;
search += 'MX: 10';


// Receive and log SSDP M-SEARCH response messages function receiveMSearchResponses () {         

  // While data in buffer, read and log UDP message while (mySocket.readable.state === "readable") {            
    var msg = mySocket.readable.read ();
    console.log ('Remote address: ' + msg.remoteAddress + ' Remote port: ' + msg.remotePort + 'Message: ' + ab2str (msg.data)); 
      // ArrayBuffer to string conversion could also be done by piping 
      // through a transform stream. To be updated when the Streams API
      // specification has been stabilized on this point.    }  

  // Wait for SSDP M-SEARCH responses to arrive        mySocket.readable.wait () .then (
    receiveMSearchResponses,          
    e => console.error ("Receiving error: ", e);
  );     
}

// Join SSDP multicast group mySocket.joinMulticast (address);

// Send SSDP M-SEARCH multicast message mySocket.writeable.write (
  {data : str2ab (search),
   remoteAddress : address,
   remotePort : port
  }) .then (
    () => {
      // Data sent sucessfully, wait for response console.log ('M-SEARCH Sent');
      receiveMSearchResponses ();
    },
    e => console.error ("Sending error: ", e);
);

// Log result of UDP socket setup.  mySocket.opened.then (
  () => {
    console.log ("UDP socket created sucessfully");
  },
  e =>console.error ("UDP socket setup failed due to error: ", e);
);

// Handle UDP socket closed, either as a result of the application 
// calling mySocket.close () or an error causing the socket to be     closed.
mySocket.closed.then (
  () => {
     console.log ("Socket has been cleanly closed");
  },
  e => console.error ("Socket closed due to error: ", e);
);

　　相比 UDP，TCP 的示例代碼顯得簡單一些

// // This example shows a simple TCP echo client. 
// The client will send "Hello World" to the server on port 6789 and log 
// what has been received from the server.
// //  Create a new TCP client socket and connect to remote host      var mySocket = new TCPSocket ("127.0.0.1", 6789);

// Send data to server mySocket.writeable.write ("Hello World") .then (
    () => {

        // Data sent sucessfully, wait for response console.log ("Data has been sent to server");
        mySocket.readable.wait () .then (
            () => {

                // Data in buffer, read it console.log ("Data received from server:" + mySocket.readable.read ());

                // Close the TCP connection                 mySocket.close ();
            },

            e => console.error ("Receiving error: ", e);
        );
    },
    e => console.error ("Sending error: ", e);
);

// Signal that we won't be writing any more and can close the write half of the connection. mySocket.halfClose ();

// Log result of TCP connection attempt.  mySocket.opened.then (
  () => {
    console.log ("TCP connection established sucessfully");
  },
  e =>console.error ("TCP connection setup failed due to error: ", e);
);

// Handle TCP connection closed, either as a result of the application 
// calling mySocket.close () or the other side closed the TCP  
// connection or an error causing the TCP connection to be closed. mySocket.closed.then (
  () => {
     console.log ("TCP socket has been cleanly closed");
  },
  e => console.error ("TCP socket closed due to error: ", e);
);

　　有什么問題可在 Github 上面給他們開 Issues:， 不過關注者廖廖（14 個 star 目前）： https://github.com/sysapps/tcp-udp-sockets/issues