title: Creating Node.js + socket.io Server/Client with users authentication, sending/receiving data
body: <p>I need to create web-based system with users live interaction (sending/receiving data) based on Node.js + socket.io. I've googled a lot of materials about Node.js and websockets but there are very much different solutions (using different frameworks and technologies) according different parts of my needs.</p>
  
  <p>Please recommend some good and effective solution to create such web-based system where users could authenticate themselves using PHP sessions and some users directly using node.js require('mysql').. </p>
  
  <p>How to keep live sessions with Node.js+socket.io after user authentication and keep updated live results even if browser window was unexpectedly closed?</p>
  
  <p>How to send/receive data arrays or only changed data keys values from one user to another and send data only to specified group of users from administrator?</p>
  
  <p>Please provide me some information and/or links according your experience with similar web-based system needs.</p>
  
  <p>Thanks in advance for your help and patience.</p>