title: A good design pattern for documenting every operation
body: <p>What is a good design pattern to document or log every operation (business logic) that is done inside the system?</p>
  
  <p>Let's say I want to write a small log or notify the user about every operation? For instance, in the system you may order a cleaning service for your house and I want to give the user feedback after each step:</p>
  
  <blockquote>
    <p>Cleaning service ordered <strong>></strong> cleaning is being done <strong>></strong> cleaning is finished</p>
  </blockquote>
  
  <p>I was thinking about Observer pattern but I'm a bit confused. Thanks.</p>