title: Implementing a single sign on for a set of WCF services
body: <p>I'm developing a set of WCF services that theoretically can be used stand-alone, but in practice have some sort of a client that usually makes multiple calls over the services in a single session.</p>
  
  <p>Our backend authentication mechanism is quite heavy and requires calls to another authentication provider service.</p>
  
  <p>However, I would like to avoid the overhead of doing the authentication on every invocation of a service.</p>
  
  <p>looking for patterns /architectural guidance around this.</p>
  
  <p>Thanks !</p>