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Use Cases

Use Cases. Week 8 CMIS570. Refresher – Class Diagrams. Appointment scheduling example Car Rental example Fitness Class example. UML diagrams. 9 diagrams Used throughout SDLC Use consistent syntax and notation. Key building block is the use-case. Use-Case.

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Use Cases

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  1. Use Cases Week 8 CMIS570

  2. Refresher – Class Diagrams Appointment scheduling example Car Rental example Fitness Class example

  3. UML diagrams • 9 diagrams • Used throughout SDLC • Use consistent syntax and notation. • Key building block is the use-case.

  4. Use-Case • Requires you to break system into use cases, small logical pieces of the system and deal with each separately. • In contrast, DFDs and ERDs encompass the entire system in one diagram.

  5. Use-Case Diagrams • Graphical specification of the system’s behavior from the perspective of the user(s). • Describes what the system does without describing how the system does it. • They are used to identify and communicate the high-level business requirements for the system.

  6. Use-Case contains: • Actor • Event/Use Case • Association • System boundary

  7. Example!Patient Admission System • A patient will call in to schedule an appointment or cancel an appointment. The office employee should be able to look up the patient’s name to determine if this is an existing patient. The office employee should also be able to look up any existing unpaid bills the patient may have with the doctor’s office. The system will look up the available times and dates for an appointment. When a day/time works for the patient, the system will add a new appointment. • Before available days and times can be recorded, an employee of the doctor’s office will need to create a master schedule. This master schedule will list all the doctor’s schedules and the days and times the office will be open for appointments. • A doctor can alter his or her schedule. When this occurs, the doctor will inform the employee of any days/times when he/she is not available. In addition, the doctor can add days/times when he/she is available to see patients.

  8. Example: Car Rental • The Cougar Car Rental Agency rents cars to customer at the airport. Customers either call to reserve a rental car for specific dates or come to the Cougar Car Rental desk at the airport to rent a car without a reservation. The car rental agents look up an existing vehicle that is available based on customer request. • When renting a car to a customer, the rental agent fills out the customer and rental car information on a rental contract, has the customer provide a credit card number as a down payment, has the customer sign the rental contract, and provide the customer a copy of the rental contract along with the keys for the rental car. • Cougar Agency also has service technicians who clean the cars when customers return them, fill cars with gas, and prepare the cars for the next rental. The service technicians also make sure that the cars receive their regular maintenance, such as oil changes, and schedule other service when the cars are in need of repair. Also, Cougar has only a limited number of each type of vehicle to rent.

  9. Example – Student Fitness Class • When a student wants to add a new class, the manager will check the fitness class schedule for availability. The manager will notify the student of an opening, and the student will pay the fee if there is an opening. The student is then registered for the class. • As new instructors are hired, their availability to teach a class will be recorded. Information on the type of class the instructor is certified to teach as well as the times he/she is available is recorded. • At times, the fitness class schedule must be changed. When this occurs, the manager will change the fitness schedule, and will then notify the instructors and students who are affected by the change.

  10. Another example – E-commerce system • Using the web, customers should be able to search for products and identify if the item is available. They should be able to order the item. The functionality that the system should have is listed below: • Receive marketing material on all products • Search through the inventory of products • Place an order • User should be able to place item into shopping cart • User should be able to provide customer information including billing information

  11. Steps in creating a Use-Case • 1. Identify use-cases (find major functions) • 2. Draw the system boundary • 3. Place use-cases on the diagram (6-8 use-cases per diagram) • 4. Identify the actors • 5. Add associations

  12. In addition… • Text documents to document use-cases since use-case diagram does not describe how those use cases are carried out by the actors. • When describing the use-case, you should focus on its external behavior – how it interacts with the actors, rather than how the use case is performed inside the system.

  13. Steps in Documentation • 1. Create a use case template that has areas labeled Basic Course and Alternative Courses. • 2. Ask “What happens?” • 3. Ask “And then what happens?” • 4. Ask, “What else can happen?

  14. Documentation examples • Patient Admission • Car Rental • Student Fitness class • E-commerce

  15. Documentation – Patient Admission System • This use case documentation shows what happens when a patient calls in to make an appointment.

  16. Makes Appointment • Main Flow • 1. patient calls in to office • 2. Staff will look up patient • 3. Staff looks up outstanding bills • 4. Staff looks up available appts • 5. Staff informs patient of available day/time • 6. Patient agrees to time/day • Exception conditions • 2e. Patient doesn’t exist, add patient to file • 3e. Patient has outstanding bills, deny appt • System Response • 2s. Patient file is accessed, patient info is returned • 3s. Billing file is accessed • 4s. Appointments file is accessed – system finds next available day and time • 6s. New appt is scheduled • Exception conditions: • 6e. Day/time not acceptable, repeat #4, 5, 6

  17. Documentation – Car Rental • Main Flow • 1. Check Driver’s license • 2. Check “Check Avail Vehicles” use case • 3. Fill out customer information on contract • 4. Fill out car information on rental contract • 5. Customer provides credit card. • 6. Contract completed • 7. Produce copy of contract • 8. Customer receives copy of contract • 9. Customer signs contract and receives keys • Exception Condition • 2e. Vehicle already located, #2 skipped • 2e. Vehicle unavailable, repeat #2 • System Response • 2s. Check Avail Vehicle use case is initiated • 3s. Begin rental contract • 4s. Update rental contract • 5s. Check credit • 7s. Contract printed • Exception condition • 5e. No credit card, tear up contract • 5e. Credit not approved, tear up contract

  18. Documentation – Student Fitness Class

  19. Documentation • 1.

  20. TIPS • Think usage scenario rather than functional requirements. • Describe usage rather than attributes and methods. • Don’t write use-case too tersely. • Don’t ignore system responses. • Don’t forget alternative courses of action

  21. Includes statement • When one use-case needs to use another use-case • Two types • Internal – only other use-cases reference • Both external actors and internal use-cases reference

  22. Examples • 1.

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