title: self message(non recursive) vs self recursive message
body: <p>What is the difference of these two messages? I searched the web a bit and most what I could find is</p>
  
  <blockquote>
    <p>A self message is a message that an object sends to itself. It is a message that represents the invocation of message of the same lifeline. A self message can represent a recursive call of an operation, or one method calling another method belonging to the same object.</p>
  </blockquote>
  
  <p>What is the benefit of additional activation bar that recursive message brings?</p>
  
  <p>In graphical notation:</p>
  
  <p>non recursive self message:</p>
  
  <p><img src="https://i.stack.imgur.com/it6wg.gif" alt="enter image description here"></p>
  
  <p>recursive self message</p>
  
  <p><img src="https://i.stack.imgur.com/Ku7bH.gif" alt="enter image description here"></p>
  
  <p>what is the difference?</p>