Lecture9 domain model visualizing
- 1. Domain model: visualizing concepts Applying UML and Patterns -Craig Larman 1
- 2. Domain Model Relationships 2 Domain Model Use Case Model Interaction Diagrams Glossary Design Requirements Business Model Classes, attributes, associations Domain objects Elaboration on some terms
- 3. A Domain Model illustrates meaningful conceptual classes in a problem domain. is a representation of real-world concepts, not software components. is NOT a set of diagrams describing software classes, or software objects and their responsibilities. It may show: concepts associations between concepts attributes of concepts 3
- 4. Domain Model: UML Notation Illustrated using a set of class diagrams for which no operations are defined. 4 A Domain Model is a description of things in the real world. A Domain Model is not a description of the software design. A concept is an idea, thing, or object.
- 5. A Domain Model is not a Software Artifact A Conceptual class: 5 Sale Date Time Sales Database Sale Date Time Print() Software Artifacts: vs.
- 6. Identify Conceptual Classes by Noun Phrase: Identify Nouns and Noun Phrases in textual descriptions of the domain. Fully dressed Use Cases are good for this type of linguistic analysis. It’s not strictly a mechanical process: Words may be ambiguous Different phrases may represent the same concepts. 6
- 7. Steps to create a Domain Model Identify Candidate Conceptual classes Draw them in a Domain Model Add associations necessary to record the relationships that must be retained Add attributes necessary for information to be preserved 7
- 8. Apply the Mapmaker Strategy Use existing names for things, the vocabulary of the domain Exclude irrelevant features Do not add things that are not there 8
- 9. UML: Associations VideoVideoStore Stocks *1 association name multiplicity -"direction reading arrow" -it has no meaning except to indicate direction of reading the association label -optional
- 10. UML: Multiplicity zero or more; "many" one or more one to forty exactly five T T T T * 1..* 1..40 5 T 3, 5, 8 exactly three, five or eight Customer Video Rents * One instance of a Customer may be renting zero or more Videos. One instance of a Video may be being rented by zero or one Customers. 0..1
- 11. GUIDELINES: Associations Only add associations for noteworthy relationships. Literally, those for which making a “note” is worthy or business motivated. Video ...Rents Influenced-by 1 1..* 1 Loan Policy ... Customer ... Important association. Need to remember. Low value association. Possible, but so what?
- 12. UML and GUIDELINES: Attributes Show only “simple” relatively primitive types as attributes. Connections to other concepts are to be represented as associations, not attributes. Payment date : Date time : Time amount : Money attributes
- 13. A Common Mistake - Classes as Attributes Rule: If we do not think of a thing as a number or text in the real world, then it is probably a conceptual class. If it takes up space, then it is likely a conceptual class. Examples: A Store is not an attribute of a Sale A Destination is not an attribute of a flight 13
- 14. Specification or Description Conceptual Classes A Class that records information about an item. Even if all Instances of the item are sold out, the description remains. Avoids duplication of recording the descriptive information with each instance of the item. 14
- 15. Description of a Service Example (Flight) 15 Airport Name vs. Flight Date Time Number Flight Date Time Flight Desc Date Time Airport Name Flies-to Described -by Describes -flights-to
- 16. The NextGen POS (partial) Domain Model 16
- 17. The NextGen POS (partial) Domain Model 17
- 18. The NextGen POS (partial) Domain Model 18