code.delx.au - gnu-emacs-elpa/blob - packages/web-server/examples/009-web-socket.el

   1 ;;; web-sockets.el --- communicate via web-sockets
   2 ;; Copyright (C) 2014  Free Software Foundation, Inc.
   3
   4 (lexical-let* ((web-socket-port 9009)
   5                (web-socket-page
   6                 (format "<html>
   7 <head>
   8 <script type=\"text/javascript\">
   9 var ws;
  10 function connect(){
  11   ws = new WebSocket(\"ws://localhost:%d/\");
  12
  13   ws.onopen    = function()    { alert(\"connected\"); };
  14   ws.onmessage = function(msg) { alert(\"server: \" + msg.data); };
  15   ws.onclose   = function()    { alert(\"connection closed\"); };
  16 }
  17
  18 function message(){ ws.send(\"foo\"); }
  19
  20 function close(){ ws.close(); };
  21 </script>
  22 </head>
  23 <body>
  24 <ol>
  25
  26 <li>Press \"connect\" to initialize the web socket connection to
  27     the server.  The server will complete the web socket
  28     handshake at which point you'll see an alert with the text
  29     \"connected\".</li>
  30
  31 <li>Press \"message\" to send the string \"foo\" to the server.
  32     The server will reply with the text \"you said: foo\" which
  33     you will see in an alert as \"server: you said: foo\".</li>
  34
  35 <li>Press \"close\" to close the connection.  After the server
  36     responds with a close frame you will see an alert with the
  37     text \"connection closed\".</li>
  38
  39 </ol>
  40 <a href=\"javascript:connect()\">connect</a>
  41 <a href=\"javascript:message()\">message</a>
  42 <a href=\"javascript:close()\">close</a>
  43 </body>
  44 </html>" web-socket-port)))
  45   (ws-start
  46    (lambda (request)
  47      (with-slots (process headers) request
  48        ;; if a web-socket request, then connect and keep open
  49        (if (ws-web-socket-connect request
  50              (lambda (proc string)
  51                (process-send-string proc
  52                  (ws-web-socket-frame (concat "you said: " string)))))
  53            (prog1 :keep-alive (setq my-connection process))
  54          ;; otherwise send the index page
  55          (ws-response-header process 200 '("Content-type" . "text/html"))
  56          (process-send-string process web-socket-page))))
  57    web-socket-port))