1. BTS430 Systems Analysis and Design using UML Design Class Diagrams (ref=chapter 16 of Applying UML and Patterns)

2. Design Process  The Design Process  Interaction Diagrams (sequence diagrams)  Responsibilities  Methods  Design Class Diagrams  Relationship between design class diagrams and interaction diagrams

3. Design Process Create/Modify Conceptual Class Diagram Create/Modify Design Class Diagram Create/Modify Interaction Diagrams Determine Responsibilities Determine Class Methods Use cases and Use Case specification

4. Interaction Diagrams  We focus on Sequence Diagrams What objects are involved in carrying out an operation? What are the responsibilities of each object?  Responsibilities will be “realized” or implemented as methods.

5. Methods  A UML method is the implementation of an operation  Illustrated In interaction diagrams, by the details and sequence of messages In class diagrams, with a UML note symbol stereotyped with >

6. Fig. 16.7 Showing Methods

7. Interaction to Design Class Diagrams  Interaction diagrams generate a set of classes and their methods.  Many of these classes originate from concepts in the domain class diagram

8. Fig. 16.7 Interaction diagrams and DCD—working together

9. Design Class Diagrams  UML convention to illustrate classes, interfaces and their associations  Static object modeling

10. Design Class Diagrams  A class diagram that is used in a software or design perspective class methods are shown navigability is often shown (for attributes) software/design details are shown (sometimes even code)

11. Fig. 16.2 Domain Model v.s. Design Model

12. Attributes  An attribute is a property of a class.  The format for attributes is: visibility name: type multiplicity= defaultValue Visibility marks include + (public) – (private), etc. Attributes are usually assumed private if no visibility is given

13. Attributes  Simple Attributes hold a value of a specific type such as an integer or a date.  Reference Attributes hold a direct reference to another object or to a collection of objects.

14. UML Attributes  Attributes of a class can be shown by Attribute text notation, such as currentSale:Sale OR Association line notation

15. Fig. 16.3 Showing attributes

16. Association line notation  A navigability arrow pointing from the source (Register) to target (Sale) object, indicating a Register object has an attribute of one Sale  The source (Register) references Sale but the Sale class does not have any knowledge of Register.

17. Association line notation  Multiplicity at the target end, but not the source end  A rolename (currentSale) only at the target end to show the reference attribute name  No association name

18. Fig. 16.4 Domain v.s. Design

19. Attributes: Text vs Association  What are data type objects? objects for which unique identity is not important e.g. date, postal codes, phone number, address, etc.  Guideline Use attribute text notation for data type objects and association line notation for others

20. Fig. 16.5 Attributes: text notation v.s. association lines

21. Collection Attributes  Array an attribute can be set to be treated as an array of attributes; shown with square braces [ ] beside the name.

22. Fig. 16.6 Collection Attributes

23. Attributes and Methods  The methods listed in a class represent the functions that can be performed on the data in the class.

24. Accessing Methods  When implementing the class, functionality is provided to set and retrieve the information stored in attributes.  Methods to set and retrieve attribute data are called accessing methods  Are often excluded from the class diagram as they are usually inferred