title: How are Boundary, Entity and Control classes defined?
body: <p>I'm referencing a book by bennet, s et al (2002). Object-orientated systems analysis and design 2nd ed. McgraawHill:Maidenhead.</p>
  
  <p>In the book when describing requirements analysis Bennet refers to three types of 'analysis class stereotypes' as a way of breaking down use case diagrams into defined classes.</p>
  
  <p>The first two seem fairly straight forward : an boundary class is the terminus between the user and the system, or the system and other systems that it relies on. An entity class is the 'information and associated behaviour of some phenomenon or concepts such as an individual, a real life object, or a real life event' i.e. the data that you're trying to model or store, such as a person.</p>
  
  <p>Finally, there are control classes which 'represent co-ordination sequencing, transactions and control of other objects'. This definition isn't as clear as Bennet states: </p>
  
  <blockquote>
    <p>"meanwhile, the boundary class represents interaction with the user and the entity clases 
    represent the behaviour of things in the application domain and storage of information that 
    is directly associated with these things"</p>
  </blockquote>
  
  <p>This rather begs the question what exactly is an application or software domain in this context? How does the control class fit in with these other two definitions?</p>