OO Packages and Layers (PPT 14)

Question 1

What s a package in UML?

Answer 1

Is a way to group related classes together

Question 2

What are packages useful for?

Answer 2

• Organisation
• Project planning and implementation
• Layering a system

Question 3

What are some problems with user interfaces?

Answer 3

• User Interface logic changes frequently compared to business logic
• Designing a user interface requires a different skill set than complex business logic
• User interface code tends to be device dependent

Question 4

What are the three tiers in a classic three tier system?

Answer 4

• Presentation layer
• Business layer
• Data Access layer

Question 5

What are some advantages of layering?

Answer 5

• Flexibility and maintainability
• Project management (specialist teams for each layer)
• Testing (Test layers independently of each other)
• Non-functional issues (scalability, availability)

Question 6

What is a circular dependency?

Answer 6

This is when two or more modules either directly or indirectly depend on each other.

Question 7

How can we solve a circular dependency?

Answer 7

We can take the classes that both areas rely on and put them in a new package