Point-of-Sale Application
•	Vision, scope
•	Architecture
Vision, scope
•	Record sales, handle payments
•	Interfaces with other applications
–	inventory, tax calculator
•	Supports multiple client-side interfaces
–	PC, PDA, touch screens
•	Supports customization for different businesses
Architecture
•	Layered
–	Varied graphical user interfaces
–	Application Logic and domain objects
–	Technical services -- application-independent
More on layers
•	GUI layer is thin -- few responsibilities
•	Technical services include error logging, database interface
•	Book focuses on application layer
–	Highest risk