title: Push Notification mechanism between a server and a client app
body: <p>I am developping a desktop application using C#, which communicates with a server over a WCF Web Service. It is supposed to be a kind of synchronization application. Meaning that when I make some changes on client app I should immediately update the server too(this is easy using service calls), but also this mechanism should be provided vice versa, a change on server must immediately be applied on several clients. I know I can make polling to my server but this doesn't look neat to me, and also I've heard of duplex services, but I'm not sure if I can use it to implement this mechanism.</p>
  
  <p>I am asking for some suggestions over this issue. Thanks in advance.</p>