title: Query whether file exists in different application
body: <p>I have I have two applications. I have a menu button on one application (service A) that is used to trigger an action in a different service (service B).</p>
  
  <p>I want to make the menu item (service A) visible only if a file is present in service B.</p>
  
  <p>Is there a clean mechanism for achieving this, rather than using absolute paths with File?</p>