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WebSocket

WebSocket is a protocol providing full-duplex communication channels over a single TCP connection. The WebSocket protocol was standardized by the IETF as RFC 6455 in 2011, and the WebSocket API in Web IDL is being standardized by the W3C.

Categories

Proxy

Example 

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Native WebSocket Example</title>
</head>
<body>
<script>
  // 웹소켓 전역 객체 생성
  var ws = new WebSocket("ws://localhost:3000");

  // 연결이 수립되면 서버에 메시지를 전송한다
  ws.onopen = function(event) {
    ws.send("Client message: Hi!");
  }

  // 서버로 부터 메시지를 수신한다
  ws.onmessage = function(event) {
    console.log("Server message: ", event.data);
  }

  // error event handler
  ws.onerror = function(event) {
    console.log("Server error message: ", event.data);
  }
</script>
</body>
</html>

Libraries

WebSocket++
https://www.zaphoyd.com/websocketpp
https://github.com/zaphoyd/websocketpp
WebSocket++ is an open source (BSD license) header only C++ library that impliments RFC6455 The WebSocket Protocol. It allows integrating WebSocket client and server functionality into C++ programs. It uses interchangable network transport modules including one based on C++ iostreams and one based on Boost Asio.

Receiving and interpreting JSON objects 

exampleSocket.onmessage = function(event) {
  var f = document.getElementById("chatbox").contentDocument;
  var text = "";
  var msg = JSON.parse(event.data);
  var time = new Date(msg.date);
  var timeStr = time.toLocaleTimeString();

  switch(msg.type) {
    case "id":
      clientID = msg.id;
      setUsername();
      break;
    case "username":
      text = "<b>User <em>" + msg.name + "</em> signed in at " + timeStr + "</b><br>";
      break;
    case "message":
      text = "(" + timeStr + ") <b>" + msg.name + "</b>: " + msg.text + "<br>";
      break;
    case "rejectusername":
      text = "<b>Your username has been set to <em>" + msg.name + "</em> because the name you chose is in use.</b><br>"
      break;
    case "userlist":
      var ul = "";
      for (i=0; i < msg.users.length; i++) {
        ul += msg.users[i] + "<br>";
      }
      document.getElementById("userlistbox").innerHTML = ul;
      break;
  }

  if (text.length) {
    f.write(text);
    document.getElementById("chatbox").contentWindow.scrollByPages(1);
  }
};

See also

Favorite site

References

  1. Things_you_should_know_before_developing_with_webSocket.pdf ↩