Conceptual Models

1. Conceptual Models

2. Models A model is a structure that represents certain aspects of some part of the reality

3. Purpose of Models - Studying the reality through studying the model • Facilitate communication and create a common view

4. Properties of Models • Models simplify • Models focus - topographic, political • Models lie - Africa, Greenland

5. Conceptual Modelling Fundamental concepts Objects Relationships Attributes Classes

6. Objects • Object: phenomenon of interest • Concrete objects • Napoleon • The Eiffel tower • A car • Abstract objects • Beethoven’s fifth symphony • The number 7 • The currency euro

7. Relationships Relationships describe how objects are associated to each other has_father owns married_to has_mother

8. Attributes Attributes are properties of objects reg. no model year colour name age salary hair colour

9. Classes Classes group together similar objects Concrete classes People Buildings Cars Abstract classes Symphonies Numbers Currencies

10. Example Conceptual Model married to owns PERSON CAR name age salary hair colour reg.no. model year colour

11. Objects in Classes PERSON CAR reg. no.: ABC123 model: Ford T year: 1922 colour: black name: Anna van Hee age: 62 salary: 3400 hair colour: white owns name: Luc Rolland age: 33 salary: 2700 hair colour: brown reg. no.: DEF456 model: Renault D year: 1928 colour: green married to reg. no.: GHI789 model: Ford T year: 1922 colour: black name: Gregor van Hee age: 61 salary: 2700 hair colour: white owns

12. Example Model Borrowers may borrow books at a library. Each book has a title, one or several authors, and an ISBN number. When a borrower borrows a copy of a book, the date of the loan has to be registered as well as the date when the copy is to be returned. If the borrower returns the copy too late or if it is damaged, she has to pay a fee. If a borrower wants a book which is not available (i.e. it is borrowed by another person), she may make a reservation for the book.

13. Example Model - Objects BOOK BORROWER COPY LOAN Borrowers may borrow books at a library. Each book has a title, one or several authors, and an ISBN number. When a borrower borrows a copy of a book, the date of the loan has to be registered as well as the date when the copy is to be returned. If the borrower returns the copy too late or if it is damaged, she has to pay a fee. If a borrower wants a book which is not available (i.e. it is borrowed by another person), she may make a reservation for the book. classes

14. Example Model - Relationships BOOK BORROWER reserves who of COPY LOAN what Borrowers may borrow books at a library. Each book has a title, one or several authors, and an ISBN number. When a borrower borrows a copy of a book, the date of the loan has to be registered as well as the date when the copy is to be returned. If the borrower returns the copy too late or if it is damaged, she has to pay a fee. If a borrower wants a book which is not available (i.e. it is borrowed by another person), she may make a reservation for the book. classes relationships

15. Example Model - Attributes BOOK BORROWER reserves who of COPY LOAN what Borrowers may borrow books at a library. Each book has a title, one or several authors, and an ISBN number. When a borrower borrows a copy of a book, the date of the loan has to be registered as well as the date when the copy is to be returned. If the borrower returns the copy too late or if it is damaged, she has to pay a fee. If a borrower wants a book which is not available (i.e. it is borrowed by another person), she may make a reservation for the book. title authors isbn name number serialno damaged loandate duedate returndate fee classes relationships attributes