1. Engineering Quality Software
SYST Engineering Quality Software
Engineering Quality Software
J.N.Kotuba
Week02

2. Agenda Develop the requirements model Use cases Use case diagrams
Schedule
Recap last lesson
Learning outcomes for today
Develop the requirements model
Use cases
Use case diagrams
Use case narratives
Activity Diagrams
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3. Last Class
Introduced Unified Process (UP) and Unified Modeling Language (UML)
Discussed
Models
Tools
Techniques
Introduced Event Tables
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4. The Unified Process Four key stages. Inception. Elaboration
Construction
Transition
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5. Unified Process:Inception
Go ahead on project.
Scope determined.
Business case developed for project.
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6. Unified Process: Elaboration
Basic architecture of the system developed.
Construction plan is approved.
Risks are identified.
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7. Unified Process: Construction.
Iterative approach to developing software.
Product will be a beta.
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8. Unified Process:Transition
Beta product is introduced to users and information is collected from users during roll-out.
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9. SYST30009 - Engineering Quality Software
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10. Modeling
Software development is the production of ‘executable models’.
These models often are abstractions of the original problem with classes added to solve the user’s problems.
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11. Different Types of Models
Use Case Model. The system from the users point of view.
Static Model. The elements of the system and how they relate to one another.
Dynamic Model. Outlines the behaviour of the system in the context of Object interactions.
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12. UML
The Unified Modeling language is (UML) a language for development object-oriented models and system designs.
It provides a complete set of graphical diagrams to specify use cases, class diagrams and the dynamic model (object interactions) of a system.
Can be used with different programming languages.
SYST Engineering Quality Software
J.N.Kotuba

13. Objectives for today
Learn how to construct a use case diagram from an event table
Learn how to build a use case narrative for each use case and why the narratives are important.
Learn how to draw an activity diagram
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14. The Pharmacy System Finalize the Event Table Identify the Actors
Build the Use Case Diagram
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15. Event table “Process”  Use Case
Event Table is a tool which helps the developer/analyst determine what an information system should do.
There are three type of events of interest to the developer.
External events
Usually initiated by an external agent or the user
Temporal events
When a point in time is reached
State events
Something changes within the system
“Process”  Use Case

16. Using System Architect
Create the UC for Pharmacy System
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17. Identifying the Actors
Where do you look?
Context Diagram
Existing system documentation (our case)
Ask the following questions
Who or what provides inputs,such as forms, voice commands, fields on input screens, etc to the system?
Who or what receives outputs, such as notifications, reports, voice messages , etc from the system?
Are interfaces required to other systems?
Are there any events that are automatically triggered at a predetermined time?
Who (User) will maintain the information system?
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18. Use Case - Actors
An actor is always outside the automation boundary of the system but may be part of the manual portion of the system
an actor is not always the same as the source of the event in the event table.
A source of an event is the initiating person, such as a customer, and is always external to the system, including the manual system.
an actor in use case analysis is the person who is actually interacting (hands-on) with the computer system itself.
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19. Your Turn… See SLATE I-C-E-01 Develop System Architect Context Diagram
Event table
Use Case Diagram
System Architect
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20. Use Case Identifies What Users Want
Use cases focus on usage of the system
Services
Behaviors
Responses
No internal structural details of the system
Can be considered as the “responsibilities” of the system
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21. Use Case Identifies What Users Want
Next
Validate use case names
Write narrative descriptions for each use case
Refining the name
May “discover” more than one use case
E.g register member
Register new member
Renew existing member
Purchase
Retail
Trade
Dealer
staff
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22. Use Case Identifies What Users Want
Refining the name
Does it tell the whole story?
Any exceptions?
Special cases?
Possible errors?
Occasional variations?
Does the name cover several related or similar processes?
Is there a more informative or enlightening name?
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23. Use Case Identifies What Users Want
Write a narrative description
Sequence of events or steps user goes through.
Focus on mainline
Straight-line sequence
Then consider exceptions, options errors
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24. Use Cases Analysts define use cases at three levels Brief Intermediate
Fully developed
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25. Use Case Narrative: Fill Prescription
Step 1.Pharmacist inputs Patient ID
Step 2.System displays patient medical record
Step 3.Pharmacist verifies dosage, potential allergic reactions and/or interaction with other medications.
Step 4.The Pharmacist fills the prescription and updates the patient’s medical record on the system with details of the new prescription.
Step 5. The system prints a label which is sent to the nurses station and the Billing Dept is given Patient and Prescription details.
Alt Step 3. If the pharmacist determines a possible negative condition exists, then the Doctor is contacted
Alt Step 4. The prescription is held for disposition.
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26. Brief Description of Create New Order Use Case
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27. Intermediate Description of Telephone Order Scenario for Create New Order Use Case
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28. Fully Developed Description of Telephone Order Scenario for Create New Order Use Case
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29. Use Case Narrative: Do’s Don’ts Use complete sentences
How is the use case initiated and how does it end
What the initial and final actions and state of the system look like
Don’ts
Use abbreviations or sentence fragments
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30. SYST30009 - Engineering Quality Software
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31. Components of the Use Case Diagram
Actor
Automation Boundary
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32. Use Case Guidelines Names Noun + Verb
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33. Use Case Guidelines Nouns SYST30009 - Engineering Quality Software
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34. Use Case Guidelines
Avoid using implementation system specific language when writing use case narratives
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35. .Summary Developing the Requirements Model: The Use Case Model
Use Cases are an informal description of the system;
They do not give information about how the system does things
Or any other details internal to the system.
They just tell us what the system will do for the users.
Concentrating on what rather than how makes them more a tool for analysis than design, but. . .
They do give us a good starting point for both
Testing the system, and
Prototyping the user interface.
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37. Activity Diagram
A type of workflow diagram that describes the user activities and their sequential flow.
Illustration:
The following slide summarizes the workflow of how a customer request for a quotation to modify a computer system is handled.
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38. SYST30009 - Engineering Quality Software
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39. Notation

41. Design Quality
A key factor in the quality of a system is how well the full effects of the individual components the system can be understood.
It is difficult to change individual components in a system unless their function is understood.
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42. Recap Lesson Learning outcomes for today
Develop the requirements model
Use cases
Use case diagrams
Use case narratives
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43. What comes next? Next Class Read Chapter 2 & Chapter 3 P27-34
Use Cases Class Diagrams
Read Chapter 2 & Chapter 3 P27-34
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J.N.Kotuba