title: How to create user/roles relation in UML class diagram?
body: <p>I have few weeks searching how to create a UML class diagram for a project.</p>
  
  <p>The system will manage users and roles of users  for access and maintain active session after login.</p>
  
  <ul>
  <li>What type of relation can I implementate between the classes?</li>
  <li>Are this class correct?</li>
  <li>Will I need other classes?</li>
  </ul>
  
  <p>Thanks in Advance!</p>
  
  <p><img src="https://i.stack.imgur.com/hrofJ.png" alt="user/roles uml class diagram"></p>