Object & Use-case Refinement
Traceability from business goals through software design
Notes:
Sequence charts always show one particular example. Type diagrams summarise the relationships between obejcts and use-cases. Here weíve shown the successive breakdown of both use-cases and the actors that take part in them. Notice how we can trace from bu
- Two layers of refinement of use-cases.
- An associated refinement of the actors, some constituents of which are software components; weíve shown the Accounts Software package as an example.
- The Accounts Software knows about Accounts, but probably not much about the sizes and weights of things óÝwhich the Distribution software probably knows more about. The types box labeled Accounts Software represents the fact that weíre treating it as a s
- The Accounts Software component takes part in two use-cases (ìenter paymentî and ìadd orderî): that is, it has two interactions with a person or another software component.
Each of these is part of a larger business use-case; and each of them represents some dialog of keystrokes, mouse clicks, API messages, etc that we havenít detailed yet. Each of them of course has some definable effect on the state of each of its particip