G05 System Design II

MVC

• The view subsystem sends updates to the controller subsystem and model subsystem

• The difference between 3 tier architectural style and MVC is that MVC is hierarchical

• Decouples data access and presentation, allowing multiple synchronized views of the same model

Concurrency

• A race condition is a design flaw where the output of a process depends on the specific sequence of other events

• Logical concurrency is when threads are provided by hardware

• Addresses the non functional requirements flexibility and maintainability as tasks are assigned to separate threads

HW/SW Mapping

• Addresses the question of how UML models can be realized in code

• Control objects are mapped to processors, entity objects to memory, and boundary object to IO devices

• The difficulty of HW/SW mapping is determining the cost of the HW needed to realize the system

Access Control

• During system design, we model access rights by associating use cases with the actors

• The access right is the row in the access matrix and it models all possible actors that interact with the system

• Capability associates a (class, operations) pair with an actor

Software Control

• Centralized design leads to additional communication overhead

• Centralized Control can be modeled using the Fork diagram

• Event-driven centralized control is when control resides within the program code