Models as System Views• UML models present

different views of systems

• Evolution of system effected by evolving models (views)– Requires well defined

relationships between models

– requires well defined notions of realization/refinement/abstraction

Rigorous Model Engineering: Part 1-Precise Semantics for UML ModelsRobert France Associate Professor

Colorado State University

System Views

Rigorous Model Engineering: Part 1- Precise Semantics for UML ModelsRobert France Associate Professor Colorado State University

Customer

Order

Order Item

Item Desc

Inventory Item Desc

Inventory

Billing

Cust name Cust addr

Quantity ordered

Quantity in stock

Product spec Price

*

1

1..*

1

1

*

*

1

1

0,1

1..*

*

0,1

*

fulfilled_from

invoices

places

consists_of

orders

stocked_info

stocks

Note: In this order system there are multiple stocks (wharehouses). The Stock Item Desc objects associated with a stock forms the catalogue of items held in that stock. The set of Item Desc objects forms the catalogue of items for this system. Each order line can be fulfilled against only 1 stock (i.e., an order line can not pull items from more than one stock).

exists = yes exists = no exists = yes

exists = yes

exists = yes exists = yes

exists = no

Conceptual Model ExampleOrder Processing System (OPS)

Rigorous Model Engineering: Part 1- Precise Semantics for UML ModelsRobert France Associate Professor Colorado State University

UML Forms of Aggregation

• Composition (strong aggregation)– parts are existent-dependent on the whole– parts are generated at the same time, before, or

after the whole is created (depending on cardinality at whole end) and parts are deleted before or at the same time the whole dies

– multiplicity at whole end must be 1 or 0..1

• (weak) Aggregation: everything else!

Journal of Information Technology ImpactVol. 3 No. 1 pp. 25-55, 2003The Impact of UML Class Diagrams on Knowledge Modelling,Disovery andPpresentations. Czejdo, Mappus, Mesa

Examples of aggregate relationships.Numbered process are preliminary and are later replaced by formal notation.