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.

HydroponicsGardeningSystem
Planning
Greenhouse
17

• Public Visible outside of the package
• Private Visible only inside the package

Planning
GardeningPlan
-PlanAnalyst
18

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

19
HydroponicsGardeningSystem
Planning
imports
access
imports
20
Component Diagrams

• A component diagram drills down one level from
  the package diagram.
• A component.
• Multiple components being connected.