title: Logout service provider(passport-saml) when identity provider(salesforce) logs out SSO
body: <p>I have created a connected App in salesforce end, and using passport saml to provide SSO to several nodeJs applications based on expressJs.</p>
  
  <p>SSO is working fine. </p>
  
  <p>However when I logout from salesforce, I can still login to the applications. </p>
  
  <p>I believe that this has something to do with cookies. Is there any way to watch a salesforce cookie and logout when it is invalidated? </p>
  
  <p>Or is there any way to send a call from salesforce to one of my routes when a logout is initiated?</p>