IBM ICE Question - Use Cases

[Balbir Singh]

Which of the following are TRUE about services resulting from use cases?

a) New requirements in use cases generally result in one or more public methods in a domain model class.

b) Private methods are required by the system's use cases.

c) Use cases drive the design of interaction diagrams, which in turn define public methods in domain model classes.

d) Each alternative scenario of a use case generally results in a new association between classes.

this question has 2 correct choices.
I answered a & c... but i guess d is also right..pls help

[Doug Wang]

I chose c and d. You cant infer public methods in a domain model class directly from new requirements. Compare a with c. Choice c is more reasonable.

[Balbir Singh]

Hi Doug,
(c) is definately right as stated on Page 75 of Larman " Use-Case realization drives the design. That is, the team designs collaborating objects and subsystems in order to perform or realize the use cases."
But I am confused between (a) and (d) since both of them use the term "generally results".

[Doug Wang]

Hi Balbir,
Another discussion on the same question is going. Two guys agree with me. One is right behind you(but not so confident).

[Yingtang Tang]

Requirements in USE CASE generally MEANS public methods in a domain model, though we don't need to highlight it in there.
So, I go to (a) and (c).
Yingtang
[ March 25, 2002: Message edited by: Yingtang Tang ]

[Sunny Liu]

Hi All
Yingtang is right, let's exam a very simple example, we will find out.
Customer buy goods, he/she can pay in cash or credit card. in this case, We may use adaptor pattern as a solution, then we do not need a additional public method in our domain.
Payment---------more alternative Payment
/ \
/ \
CashPayment CreditCardPayment
our Domain only needs deal with Payment.
I hope It will help someone who chosen "D"