title: Long polling for real time messages/updates
body: <p>What is a good strategy for implementing long polling in a .Net application.</p>
  
  <p>Would it mean having a JS setInterval() based approach to keep polling the server for updates that can be rendered on the page. I have always thought that that could be a challenge when it comes to scalability as it seems it would generate a lot of extra requests to the web server. I have read that this type of functionality should be implemented using a non blocking web server (single threaded) NODE.js etc...
  Since there's only one thread/event loop it seems like the requests would have to be very lightweight to service several requests in a timely fashion. Can Node.Js trigger db calls?</p>
  
  <p>I have seen an online dating site where you receive notification in the form of a fad-in/fade-out popup when someone visits your profile when you're currently logged into the system. I am impressed that something like that can work so well for a high volume site. </p>
  
  <p>Is it reasonable to assume that this type of notification system is implemented using long polling? Based on constantly polling through JS?</p>
  
  <p>I am seeing similar behind the scenes updates her on the SO site as well (messages/votes etc) Does this use a similar strategy as well? </p>