Classification

1. Classification

2. Classification is hard. How do you decide what is important? What is important for animals? Why pick those characteristics? (Maybe those are important for some purposes, though.) What about chemicals?

3. Identifying Classes and Objects Classical categorization Conceptual clustering Prototype theory

4. Classical Categorization All entitities that have a given property or collection of properties in common form a category. Necessary and sufficient properties.

5. Conceptual Clustering Create a concept, and see how close it is to the concept.

6. Prototype theory How closely does it resemble a set of prototype objects.

7. Approaches to Analysis Classical Approaches Shlaer and Mellor Tangible things: Cars, telemetry data, pressure sensors Roles: Mother, teacher, politician Events: Landing, interrupt, request Interactions: Loan, meeting, intersection

8. Database modeling perspective People: Humans who carry out some function Places: Areas set aside for people or things Things: Physcial objects, or groups of objects, that are tangible Organizations: Formally organized collections of people, resources, facilities, and capabilities having a defined mission, whose existence is largely independent of individuals Concepts: Principles or ideas not tangble per se; used to organize or keep track of business activities and/or communications Events: Things that happen, usually to something else at a given date and time, or as steps in an ordered sequence

9. Coad and Yourdon Structure: �Is a� and �part of� relationships Other systems: External systems with which the application interacts Devices: Devices with which the application interacts Events remembered: A historical event that must be recorded Roles played: the different roles users play in interacting with the application Locations: Physical locations, offices, and sites important to the application Organizational units: Groups to which the users belong

10. Use Case Analysis The design is good if it fits the use cases. Compile a set of scenarios. Step through them. CRC Cards Class/Responsibilities/Collaborators Used to help record the use case analysis Can spread them on a table, etc.

11. UML What is the point of a notation? What does a layering diagram mean?

12. Multiple Views There is a single system design, but no single diagram of it serves to capture all the essence. You can think of it as an object that requires multiple camera angles to capture all of it.

13. Types of Diagrams Structure diagrams Package diagram Class diagram Component diagram Deployment diagram Object diagram Composite structure diagram Use dase diagram Activity diagram State machine diagram Interaction diagram Sequence diagram Communication diagram Interaction overview diagram Timing diagram

14. Use In Practice Let it be driven by your needs. No need to diagram for the sake of diagramming. How do you know you need one? Do not need to be too rigid about it, the point is communication, to others and also to yourself.

15. Conceptual, Logical, Physical Models Conceptual model is in the problem domain. Logical model is implementable, but not specific to a language, contains key abstractions. Physical model is specific to the programming language.

16. Package Diagram Can be used to organize classes, also use cases. pcpc

17. Public: Visible outside of the package Private: Visible only inside the package

18. Dependency relationship Use an arrow Can aggregate if we go up. Draw Can be a import or access.

20. Component Diagrams A component diagram drills down one level from the package diagram. A component. Multiple components being connected.