title: What is the advantage of WSDualHttpBinding in WCF?
body: <p>So far, no one can really offer any benefit of using dual channel over a client polling system except for the immediate notification you can get from the dual channel.  Every other point says if you dont need immediate notice the dual binding provides negative value - anyone disagree with this?</p>
  
  <p>How much benefit would there be to using WSDualHttpBinding with IIS hosted service vs. a client poll that calls the WCF service, assuming in the latter the service cached the data in question?</p>
  
  <p>This scenerio would be for a notify type of service where the clients need to be notified by the service when an event occurs.</p>
  
  <p>Specifically, what advantages would WSDualHttpBinding provide over polling?
  ie: Less network traffic, faster to design, easier to maintain, more control ???</p>
  
  <p>From what i understand, WSDualHttpBinding is less scalable than client polling, so why use it at all?  Edit: As Matt supplied, time critical can be one reason for the duplex binding.</p>
  
  <p>Here is what i have so far:</p>
  
  <p>WSDualHttpBinding</p>
  
  <p>adv:  can get immediate response w/o waiting on polling timer</p>
  
  <p>dis: less scalable than WsHttpBinding</p>
  
  <p>dis: less firewall friendly</p>
  
  <p>dis: slower than WSHttpBinding</p>
  
  <p>I'll add to this based on comments, please let me know if i state anything incorrectly.</p>
  
  <p>thanks for you input :-)</p>