title: Does socket.io upgrade transport to websocket from polling ?
body: <p>I am using nodejs with socket.io and express frame work. Following is the log output I get, when I run command</p>
  
  <pre><code>DEBUG=* /bin/www
  </code></pre>
  
  <p>Following is the log output.</p>
  
  <pre><code>  engine intercepting request for path "/socket.io/" +2m
    engine handling "GET" http request "/socket.io/?EIO=3&amp;transport=polling&amp;t=1414498393419-0" +0ms
    engine handshaking client "WECN1dP0tobacKc8AAAB" +1ms
    engine:socket sending packet "open" ({"sid":"WECN1dP0tobacKc8AAAB","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":60000}) +0ms
    engine:polling setting request +0ms
    engine:socket flushing buffer to transport +0ms
    engine:polling writing "  �0{"sid":"WECN1dP0tobacKc8AAAB","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":60000}" +1ms
    engine:socket executing batch send callback +1ms
    socket.io:server incoming connection with id WECN1dP0tobacKc8AAAB +2.5m
    socket.io:client connecting to namespace / +1.3m
    socket.io:namespace adding socket to nsp / +2.5m
    socket.io:socket socket connected - writing packet +1.3m
    socket.io:socket joining room WECN1dP0tobacKc8AAAB +0ms
    socket.io:client writing packet {"type":0,"nsp":"/"} +1ms
    socket.io-parser encoding packet {"type":0,"nsp":"/"} +2.5m
    socket.io-parser encoded {"type":0,"nsp":"/"} as 0 +0ms
    engine:socket sending packet "message" (0) +1ms
    socket.io:socket joined room WECN1dP0tobacKc8AAAB +5ms
    engine intercepting request for path "/socket.io/" +140ms
    engine handling "GET" http request "/socket.io/?EIO=3&amp;transport=polling&amp;t=1414498393557-1&amp;sid=WECN1dP0tobacKc8AAAB" +0ms
    engine setting new request for existing client +1ms
    engine:polling setting request +0ms
    engine:socket flushing buffer to transport +0ms
    engine:polling writing "�40" +0ms
    engine:socket executing batch send callback +0ms
    engine upgrading existing transport +39ms
    engine:socket might upgrade socket transport from "polling" to "websocket" +0ms
    engine intercepting request for path "/socket.io/" +16ms
    engine handling "GET" http request "/socket.io/?EIO=3&amp;transport=polling&amp;t=1414498393618-2&amp;sid=WECN1dP0tobacKc8AAAB" +0ms
    engine setting new request for existing client +0ms
    engine:polling setting request +0ms
    engine:ws received "2probe" +2ms
    engine:ws writing "3probe" +0ms
    engine:socket writing a noop packet to polling for fast upgrade +100ms
    engine:polling writing "�6" +0ms
    engine:ws received "5" +4ms
    engine:socket got upgrade packet - upgrading +0ms
    engine:ws received "2" +25s
    engine:socket packet +0ms
    engine:socket got ping +0ms
    engine:socket sending packet "pong" (undefined) +0ms
    engine:socket flushing buffer to transport +0ms
    engine:ws writing "3" +0ms
    engine:ws received "2" +25s
    engine:socket packet +0ms
    engine:socket got ping +0ms
    engine:socket sending packet "pong" (undefined) +0ms
    engine:socket flushing buffer to transport +0ms
    engine:ws writing "3" +0ms
    engine:ws received "2" +25s
    engine:socket packet +0ms
    engine:socket got ping +0ms
    engine:socket sending packet "pong" (undefined) +0ms
    engine:socket flushing buffer to transport +0ms
    engine:ws writing "3" +0ms
    engine:ws received "2" +25s
    engine:socket packet +0ms
    engine:socket got ping +0ms
    engine:socket sending packet "pong" (undefined) +0ms
    engine:socket flushing buffer to transport +0ms
    engine:ws writing "3" +1ms
  </code></pre>
  
  <p>I don't see any log message that confirms transport upgrade. Also the ping-pong messages keep  happening. </p>
  
  <p>Does this mean the websocket transport is established ?</p>