UML sofeware engineer

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Lesson 11

Use Case Alternative Courses

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Use Case Alternative Courses

 Need for alternative courses

 Errors

 Sections

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Need for Alternative Courses

 Nothing works as it is suppose to  Customers change their mind

 Human errors are easily made

 Transactions can be done different ways  Pay by Check  Pay by Cash  Pay by Credit Card

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Need for Alternative Courses

There are really two types:  Alternative courses that are user problems

 Customer does not have enough cash  Customer number does not exist

 Alternative courses that are input errors  Credit card is invalid  Item is not in stock  Customer number is entered in error

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Errors

Recall use case for Buy Items:  2. The customer gives the upc to the

system  3. Displays the price and running total

Alternative Courses:  Line 2: If the upc is invalid, display that it is

invalid and ask cashier for another upc

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Errors

Recall use case for Buy Items:

 6. The customer makes a payment  7. Displays the balance due

Alternative Courses:  Line 6: If the customer has insufficient

cash is invalid, cancel the sale

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Errors

Recall use case for Rent Car:

 2. The customer gives dates and times needed with type of car  3. Displays what is available with the price

Alternative Courses:  Line 2: If no car is available, thank the

customer for considering us

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Errors

Recall use case for Rent Car:

 6. The customer makes a payment  7. Prints the contract and the receipt

Alternative Courses:  Line 6: If the customer’s payment is

unsatisfactory, cancel the rental

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Sections

 Sections are a convenient way to handle alternative actions

 Sections are a segment of a use case executed out of sequence

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Sections

Recall use case for Buy Items:

 6. The customer makes a payment

is replaced by

 6. Customer chooses payment type

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Sections

Section: Pay by Cash

 1. The customer makes a payment

 2. Displays the balance due

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Sections

Section: Pay by Check

 1. The customer submits check and personal picture identification

 2. Generates a check verification request

 3. Receives check approval

 4. Displays check is okay or not okay

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Sections

Recall use case for Rent Car:

 2. The customer gives dates and times needed with type of car

 2. Customer chooses return at place of rental (return) or another city (one way)

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Sections

Section: Return Car Rental

 1. The customer gives dates and times needed with type of car

 2. Displays what is available with the price

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Sections

Section: One Way Car Rental

 1. The customer gives dates, times, and type of car  If a car is available

 1. The customer gives the city name where the car is to be returned to  2. Displays what is available with the price

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Summary

 Use Cases always contain errors

 Sections are a convenient way to handle multiple choices

 Usually errors are added to use cases in a second writing

 This allows users to study the use case while it is simple before complexities are added