Detail Design Extending UML and Object Design

Object Design

Extending UML

Constraints: Telemarketing Example

Constraints: Contact Management Example

OCL (Object Constraint Language) OCL is a formal language intended for specifying constraints Most OCL statements consist of the following structural elements – context -- defines a domain within which the expression is valid (e.g. an instance of a specific type or class, or a link) – a property of that instance which is the context for the expression -- e.g. attributes, association-ends – an OCL operation which is applied to the property -- arithmetic operators, set operators and type operators OCL statements can also include keywords – e.g. and, or, implies, if, then, else, not, in

Examples of OCL Expressions

Specifying OCL Constraints

Example OCL Operation Specification

Notes and Tags

Notes and Tags: Contact Management Example

Using Notes to Express OCL Constraints

Object-Oriented Detailed Design

Class Specification – Attributes and Operations

Class Specification Example

Attribute and Operation Visibility

Derived Information Derived information is information which is computed from other model elements – a kind of constraint that applies to an attribute or an association – derived information may make the model more readable Knowing which information is derived is more important in the design model – during design, access to information should be optimised -- actual data (derived information is stored after it has been derived) -- virtual data (derived information is dynamically recomputed each time) The UML notation for derived information is a solidus / in front of the name of the derived attribute or association

Derived Attribute Example

Summary Extending UML – additional modelling concepts ● stereotypes ● comments ● constraints – OCL (Object Constraint Language) References – Maciaszek, section 5.11, Bennett et al., section 10.5