title: How to query PingFederate
body: <p>I am new to Ping Federate and have a few questions.  I am trying to understand from an architect's perspective a number of things around querying and APIs.  I understand Ping Federate supports attribute-query request.  This seems very much doable but only appears to work for querying additional attributes based on the current SAML instance.</p>
  
  <p>What I am trying to understand is what options exist for querying a 'user list' or querying attributes for specific users?  I need to check users for changes in specific attributes or have a means to be notified of changes to specific attributes.  Based on the following somewhat related link, I believe it is not possible:</p>
  
  <p><a href="https://stackoverflow.com/questions/25692571/in-pingfederate-is-there-an-api-to-query-a-list-of-users-and-a-list-of-groups">In PingFederate, is there an API to query a list of users and a list of groups?</a></p>
  
  <p>But, I would think architecturally something like this should be possible. Is there a way to query PingFederate in the manner above?  Or have it notify you of changes?  Directly or indirectly?</p>
  
  <p>Regards...</p>