1. CSC 216/002 Lecture 2

2. UML Class Diagrams  What are the little numbers for on the edges leading from the box representing a class?

3. Is-a vs. Has-a  A poodle is-a dog.  A car has-a transmission.  A poodle is-a dog.  A car has-a transmission.

4. Aggregation vs. Association  An aggregation is a set of objects that make up a unit.  Example?  An association is two or more objects that work together, but one is not part of another.  Example?  An aggregation is a set of objects that make up a unit.  Example?  An association is two or more objects that work together, but one is not part of another.  Example?

5. Class-Responsibility-Collaborator  Classes: To find the objects, look for the nouns.  Responsibilities: Things a class knows or can do.  Collaborators: Other classes that are involved in fulfilling these responsibilities.  Classes: To find the objects, look for the nouns.  Responsibilities: Things a class knows or can do.  Collaborators: Other classes that are involved in fulfilling these responsibilities.

6. Requirements for the Course- Registration System  The mission is to automate registration of students for courses at a university.  Each student takes one or more courses, which are identified by name and course number.  Each course is worth one or more credit hours.  A student can register for up to 21 credit hours.  For each course that is taught, the students are placed into sections, which may meet at different times and be taught by different instructors.  If more than 50 students want to take the same class, another section will be added.  If fewer than 5 students register for a section, it will be canceled.  If no instructor can be persuaded (or hired) to teach a class, it will be canceled.  Students may specify alternate courses or sections, in case of a time conflict, or if their first-choice class is canceled.  After a student has registered for courses, (s)he will be e-mailed a class schedule.  The mission is to automate registration of students for courses at a university.  Each student takes one or more courses, which are identified by name and course number.  Each course is worth one or more credit hours.  A student can register for up to 21 credit hours.  For each course that is taught, the students are placed into sections, which may meet at different times and be taught by different instructors.  If more than 50 students want to take the same class, another section will be added.  If fewer than 5 students register for a section, it will be canceled.  If no instructor can be persuaded (or hired) to teach a class, it will be canceled.  Students may specify alternate courses or sections, in case of a time conflict, or if their first-choice class is canceled.  After a student has registered for courses, (s)he will be e-mailed a class schedule.

7. Requirements for the Flight- Reservation System  The mission is to allow round-trip airline tickets to be bought over the Web.  Each customer specifies an origination point, a destination, and dates for outbound and return flights.  The customer reserves one outbound flight and one return flight from a menu presented by the system.  Each choice that the system presents consists of one or more flight segments (there may be a change of planes).  The customer may buy tickets for one or more passengers.  No more tickets can be sold for a flight than there are seats on the plane.  Each passenger is assigned to a specific seat.  The system calculates the total cost of the tickets by adding the cost of the individual segments.  If dissatisfied with the cost, the customer may select alternate flights.  After a customer has bought a ticket, (s)he will be e-mailed a confirmation.  The mission is to allow round-trip airline tickets to be bought over the Web.  Each customer specifies an origination point, a destination, and dates for outbound and return flights.  The customer reserves one outbound flight and one return flight from a menu presented by the system.  Each choice that the system presents consists of one or more flight segments (there may be a change of planes).  The customer may buy tickets for one or more passengers.  No more tickets can be sold for a flight than there are seats on the plane.  Each passenger is assigned to a specific seat.  The system calculates the total cost of the tickets by adding the cost of the individual segments.  If dissatisfied with the cost, the customer may select alternate flights.  After a customer has bought a ticket, (s)he will be e-mailed a confirmation.