meeting -*- Outline -*-

* Case Study: The NextGen POS System (Larman, Ch 3)
  
** NextGen POS (3.1)
  The case study we'll use, as in the book, is a point-of-sale (POS)
  system.

  Purpose is to record retail sales and handle payments.

  Interfaces to other applications: tax calculators, inventory control
	     these may be remote (e.g., inventory)

  Must be fault tolerant, able to record sales even if communications down

  Must support multiple terminals (eg., thin client, PC, touch screen, ...)

  Goal is to create a commercial POS system we can sell to various clients,
       customized for each

** Architectural Layers and emphasis (3.2)
   Typical OO system has several architectural layers (subsystems)

------------------------------------------
      ARCHITECTURAL LAYERS (TYPICAL)

User interface  -- graphics, windows

   [ DialogBox ]

   =====================

Application logic -- domain objects

   [ Sale ]  [ Payment ]

   =====================

Technical services -- logging, persistence

   [ Log ]    [ PersistenceFacade ]

------------------------------------------
        OO A/D is most relevant for application logic and technical services
        Typically reuse the UI layer, although it may also be done in OO

        UI layer has little responsibility (thin)

        Main emphasis is on the application logic layer
        Secondary emphasis on technical services layer

        Minor emphasis on the UI layer:
              how to connect to other layers, and
              usability engineering issues