title: Composition in UML
body: <p>In UML diagrams when considering composition. Should we use it in logical or implementation sense. Examples for both terms: </p>
  
  <ul>
  <li>Implementation - An airport will contain a reference to the country. In other words, a country is part of the Airport. </li>
  <li>Logical - A country can have zero or many airports. In other words, an airport is part of the country.</li>
  </ul>
  
  <p><a href="https://i.stack.imgur.com/n60US.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/n60US.png" alt="UML example diagram"></a></p>
  
  <p>From diagram above, which case shows correct usage of composition?
  NOTE: if neither of these cases are good, please suggest other ways to show relationship between country and airport.</p>