情境
A library system needs to model books, copies, members, librarians, loans, reservations, and fines with clear ownership and multiplicity rules.
這張圖裡有什麼
看懂背後的決策。
01
Separate Book (metadata) from BookItem (physical copy) to allow multiple copies and track status per copy.
02
Use composition for Library-Book and Book-BookItem, aggregation/association for member loans and reservations, and dependency for fine generation.
Use this diagram when designing a library circulation system, integrating with an OPAC, or modeling inventory and loan lifecycle.