8 Steps to Effective Use Cases

Transcription

1 8 Steps to Effective Use Cases Linda Westfall Sponsored by Linda Westfall 3000 Custer Road Suite 270, PMB 101 Plano, TX phone: (972) fax: (972)

2 Attendees are on mute Logistics Type your questions into the Chat area - Louise will ask questions between slides Slides & a recording of this presentation will be available online Certificates are available for RUs, PUs, etc. You will receive an tomorrow telling you: How to request a certificate of attendance How to access slides & recording 8 Steps to Effective Use Cases Use cases identify how the system will be used. 1. Define the system boundaries 2. Identify the actors 3. Determine interactions 4. Establish pre & post conditions 5. Document the main success scenario 6. Branch to alternatives & exceptions 7. Merge or create sub-use cases as appropriate 8. Record additional information

3 Step 1 - Define the System Boundaries System Under Consideration = Step 2 Identify the Actors Customer Owner Clearing House System Under Consideration =

4 Another Perspective System Boundaries System Under Consideration = Another Perspective Identify Actors Customer Owner Clearing House System Under Consideration =

5 Where is the Cash Register? Customer Owner Clearing House System Under Consideration = Where is the Cash Register? (cont.) Customer Owner Cash Register (Actor or Not?) Clearing House System Under Consideration =

6 Yet Another Perspective System Boundaries Reader System Under Consideration = Reader Yet Another Perspective Identify Actors Reader Gas Pay Customer Owner Clearing House System Under Consideration = Reader

7 Step 3 - Determine Interactions For each identified actor, determine: Main tasks or functions performed using the system Data acquired, produced, or changed in the system Information given to or wanted from the system Notifications or alarms wanted from the system Primary actor: Initiates the use case The use case is initiated for that actor Secondary actor: Other actor(s) involved in the use case Use Case Diagrams Primary Actor Customer Purchase Gas at Pump with Purchase Car Wash at Pump Purchase Gas by Post-Paying Clearing House Owner Generate Monthly Tax Reports Accept Payment for Gas Purchase (Post-Pay)

8 Use Case Diagram Secondary Actor Customer Purchase Gas at Pump with Purchase Car Wash at Pump Purchase Gas by Paying Clearing House Owner Generate Monthly Tax Reports Accept Payment for Gas Purchase (Post-Pay) Step 4 - Establish Pre & Post Conditions For each use case establish its: Pre conditions (entry criteria): What must be true before the use case can start? Post conditions (exit criteria): What must be true before the use case is successfully completed? Purchase gas at with credit card - example: Pre conditions Post conditions

9 Use Case - Example Use Case: Accept Payment for Gas (Post-Pay) Primary Actor: Secondary Actors: Customer, Bank Consortium Preconditions: Gas has been successfully ed Customer has arrived at to pay for gas Post Conditions: Payment has been received Customer was able to pay for gas with payment type of preference Customer received receipt Step 5 - Document Main Success Scenario Main Success Scenario: 1. acknowledges next customer 2. Customer pays for the gas they ed 3. gives customer change & receipt

10 Main Success Scenario Detailed Example Main Success Scenario: 1. greets Customer & asks which 2. Customer identifies s 3. polls system for information 5. confirms price with customer & acknowledges price with system 7. ask if other items & Customer responds no 8. asks for payment type & Customer pays in cash 9. enters cash tendered into cash register 11. provides change & receipt to customer 12. ends transaction 4. System reports gallons ed & total price 6. System accepts price & displays price on cash register display 10. System calculates & displays change & prints receipt 13. System saves transaction information & resets Step 6 - Branch to Alternatives & Exceptions Alternative Scenarios: 1. greets Customer & asks which 2. Customer identifies s 3. polls system for 4. System reports gallons ed & total information price 5. confirms price with customer & 6. System accepts price & displays price on acknowledges price with system 5a1. Customer identified cash register wrong display 7. ask if other items & Customer & changes responds no identification 8. asks for payment type 5a2. & cancels previous 5a3. System resets to no Customer pays in cash identified p y 9. enters cash tendered 5a4. into Return cash to step 3 register 11. provides change & receipt to customer 12. ends transaction 10. System calculates & displays change & prints receipt 13. System saves transaction information & resets

11 Other Alternative - Examples Alternative Scenarios: 1. greets Customer & asks which 2. Customer identifies s 3. polls system for information 5. confirms price with customer & acknowledges price with system 4. System reports gallons ed & total price 6. System accepts price & displays price on cash register display 7. ask if other items & Customer 7a1. Customer purchase responds no another item 8. asks for payment type 7a2. & enters price for 7a3. System accepts price & Customer pays in cash additional item in cash displays item price & register running total price on 9. enters cash tendered into cash cash register register 10. System calculates & displays change & prints receipt 11. provides change & receipt 7a4. to Return to step 8 customer 12. ends transaction 13. System saves transaction information & resets Other Alternative Examples (cont.) Alternative Scenarios: 1. greets Customer & asks which 2. Customer identifies s 3. polls system for information 5. confirms price with customer & acknowledges price with system 4. System reports gallons ed & total price 6. System accepts price & displays price on cash register display 7. ask if other items & Customer responds no 8. asks for payment type & Customer pays in cash 4a1. System can not communicate with 9. enters cash tendered into cash register 4a manually System checks calculates & displays change & prints receipt 11. provides change & receipt to display & enters customer amount into cash register 12. ends transaction 4a3. Return to step 13. System 7 saves transaction information & resets

12 Exception Scenarios: Exception Examples 1. greets Customer & asks which 2. Customer identifies s 8a1. asks for payment 8a2. System reads & parses 3. polls system for information type & Customer swipes magnetic strip invalid 4. credit System card type reports gallons ed & total (not accepted price type of card) 5. confirms price with customer & acknowledges price with system 8a3. System displays error 6. System accepts price & displays price on cash register display 8a4. Return to step 8 7. ask if other items & Customer responds no 8. asks for payment type & Customer pays in cash 9. enters cash tendered into cash register 11. provides change & receipt to customer 12. ends transaction 10. System calculates & displays change & prints receipt 13. System saves transaction information & resets Exception Examples (cont.) Exception Scenarios: 1. greets Customer & asks which 2. Customer identifies s 3. polls system for 4. System reports gallons ed & total information 8b1. asks price for payment 8b2. System reads & parses 5. confirms price with customer type & & Customer 6. System swipes magnetic strip accepts price & displays price on acknowledges price with system invalid credit cash card register display (expired, reported stolen 7. ask if other items & Customer or over limit) correctly 8b3. System establishes responds no (after one or more tries) communications with Bank Consortium & 8. asks for payment type & transmits merchant Customer pays in cash information, credit card 9. enters cash tendered into cash information & register 10. System calculates & displays transaction change amount & prints receipt 11. provides change & receipt 8b4. to Bank Consortium customer disapproves transaction 12. ends transaction 8b5. System displays disapproval 8b6. Return to 13. step System 8 saves transaction information & resets

13 Exception Example Example Exception Scenarios: 4a2. manually checks display & enters amount into cash register 4a3. Return to step 7 8c1. asks for payment type & Customer swipes invalid credit card type (not accepted type of card) 8c4. Return to step 8 8d1. asks for payment type & Customer swipes invalid credit card (expired, reported stolen or over limit) correctly (after one or more tries) 8d4. Bank Consortium disapproves transaction 8d6. Return to step 8 4a1. System can not communicate with 8c2. System reads & parses magnetic strip 8c3. System displays error 8d2. System reads & parses magnetic strip 8d3. System establishes communications with Bank Consortium & transmits merchant information, credit card information & transaction amount 8d5. System displays disapproval Step 7 - Merge or Create Sub-Use Cases <<include>> behavior similar across more than one use case generalization one use case similar to another case but does a bit more <<extend>> generalization that can only occur at a declared extension point Use Case Extension points <<include>> Read & Validate Actor <<extend>> (extension points) At step n Purchase Car Wash Generalization Put card in Reader Incorrectly (one or more times)

14 Step 8 Record Additional Information Other information that should be captured for each use case: Use case identifier & use case name Created by & date Modification history (modifiers & dates) Use case description Priority Frequency of use Related business rules Assumptions 8 Steps to Effective Use Cases Use cases identify how the system will be used. 1. Define the system boundaries 2. Identify the actors 3. Determine interactions 4. Establish pre & post conditions 5. Document the main success scenario 6. Branch to alternatives & exceptions 7. Merge or create sub-use cases as appropriate 8. Record additional information

15 Reminders Slides & a recording of this presentation will be available online Certificates are available for RUs, PUs, etc. You will receive an tomorrow telling you: How to request a certificate of attendance How to access slides & recording