title: Lock web object among users in asp.net mvc
body: <p>I have an asp.net mvc site where users can select a number of objects, they are identified by a unique id.
  What I would like to do is:</p>
  
  <ol>
  <li>User A opens an object</li>
  <li>When user B tries to open the same object, a message will appear saying this is already open by user A, therefore is inaccessible.</li>
  </ol>
  
  <p>I guess the server would have a sort of 'shared' session that can be queried in every Ajax request, to check if the object is already open by a different user. When the object is closed then that id should be removed from the shared list of opened objects. What would be the best approach for this?</p>