websocket协议
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websocketd::

  http://websocketd.com/
  https://github.com/joewalnes/websocketd

  使用:
  websocketd --port=8080 bash ./counter.sh  
  % 启动websocket,当client连接后
  % 会执行counter.sh,并输出到client


other websocket::

  https://github.com/uNetworking/uWebSockets
  https://socket.io/
  https://github.com/theturtle32/WebSocket-Node