Test 5

Question 1

AOP

Answer 1

Aspect-Oriented Programming (AOP) complements OO programming by allowing the developer to dynamically modify the static OO model to deal with cross cutting concerns

Question 2

Cross-cutting concerns

Answer 2

Concerns which “cross-cut” the class structure, lowering cohesion and increasing coupling.

Question 3

CCC Consequences

Answer 3

Code Tangling

Code Scattering

Question 4

Code Tangling

Answer 4

1) Code for CC is mixed with the business logic.

2) Reduces cohesion

Question 5

Code Scattering

Answer 5

1) Code is duplicated because it is needed in multiple places
2) Reduces coupling

Question 6

Lock handling Problem

Answer 6

1) Business logic code (put and get) is mixed with concurrency control code resulting in code tangling and poor cohesion
2) Have to add locking code correctly to every business logic code resulting in code scattering
3) Failure to do so would lead to hard to find bugs
4) Need a single, global lock resulting in extra coupling

Question 7

Lock handling Pros

Answer 7

1) Avoids code scattering and tangling
2) Lock is localised as a private instance variable
3) Reusable simply by writing a new concrete aspect

Question 8

AOP and Design Patterns Pros

Answer 8

1) Greater modularisation of concerns
2) Avoid code tangling and scattering
3) Easier software evolution
4) Greater code reuse
5) Easier management (easier to split tasks)
6) Cheaper implementation of new features

Question 9

AOP and Design Patterns Cons

Answer 9

1) Program flow is hard to follow
2) Tendency to use CCC everywhere, leading to poor designs
3) Everybody on the team needs to be up to speed with AOP
4) Tools limited to those which support AOP language in use

Question 10

AspectJ

Answer 10

1) Java AOP framework
2) Classes and aspects are written separately
3) “woven” together at bytecode generation time
4) Nothing in class code referes to the aspects

Question 11

AspectJ advice kinds

Answer 11

before - code to be executed before join point
after - code to be executed after join point
around - replaces the code
pointcut - shows where the CC should be applied

Question 12

AOP and Design Patterns

Answer 12

1) Observer and Singleton are the only ones who have any benefits
2) Pure fabrications have no sensible inheritance relationships outside the pattern
3) Combing patters will make AOP solutions more problematic

Question 13

Advice

Answer 13

Additional code that you want to apply to your existing model

Question 14

Join point

Answer 14

Place where CCC crosscuts the code

Question 15

Point cut

Answer 15

Point of execution in the application at which cross-cutting concern needs to be applied

Question 16

Aspect

Answer 16

The combination of the point-cut and the advice