title: WPF / WCF Push Notification
body: <p>Does .NET 3.5 (WCF, or other) offer any type of push notification service?</p>
  
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  <p>I have a server and a client. I want a service to run on the server and if x happens then push a notification to the client. I don't want to pull the server every x minutes to gather the information.</p>