Subsystem Guidelines ◆( Goals Loose coupling <<subsystem>> A -Portability,plug-and-play compatibility Insulation from change Independent evolution <<subsystem>> ◆ Strong Suggestions B Do not expose details,only interfaces Depend only on other interfaces <<subsystem>> C Key is abstraction and encapsulation Object Oriented Analysis and Design 5Object Oriented Analysis and Design 5 Key is abstraction and encapsulation A <<subsystem>> B <<subsystem>> C <<subsystem>> Subsystem Guidelines  Goals ▪ Loose coupling ▪ Portability, plug-and-play compatibility ▪ Insulation from change ▪ Independent evolution  Strong Suggestions ▪ Do not expose details, only interfaces ▪ Depend only on other interfaces