Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and the Unified Process, Second Edition
by Craig Larman
23.8. Facade (GoF)
Another requirement chosen for this iteration is pluggable business rules. That is, at predictable points in the scenarios, such as when makeNewSale or enterItem occurs in the Process Sale use case, or when a cashier starts cashing in, different customers who wish to purchase the NextGen POS would like to customize its behavior slightly.
To be more precise, assume that rules are desired that can invalidate an action. For example:
Suppose when a new sale is created, it is possible to identify that it will be paid by a gift certificate (this is possible and common). Then, a store may have a rule to only allow one item to be purchased if a gift certificate is used. Consequently, subsequent enterItem operations, after the first, ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access