Object Oriented Methodologies

1. SYST39409 - Object Oriented Methodologies Object Oriented Methodologies Week02

2. Agenda • Assignment No 1 posted • Review details • SLATE-Weekly Topical Outline and Schedule modified • Recap last lesson • Learning outcomes for today • Develop the requirements model & the Unified Process • Use cases • Use case diagrams • Use case narratives SYST39409 - Object Oriented Methodologies

3. Last Class • Introduced Unified Modeling Language (UML) • Discussed • Models • Tools • Techniques SYST39409 - Object Oriented Methodologies

4. Context Diagram –Pharmacy System SYST39409 - Object Oriented Methodologies

5. Objectives for today • Explain the difference between the Waterfall SDLC and the unified process • Learn how to use the Event Table Technique to identify use cases • Learn how to construct a use case diagram • Learn how to build a use case narrative for each use case and why the narratives are important • Be able to explain the difference between the system boundary and the automation boundary SYST39409 - Object Oriented Methodologies

6. The Unified Process • Four key stages. • Inception. • Elaboration • Construction • Transition SYST39409 - Object Oriented Methodologies

7. Unified Process:Inception • Go ahead on project. • Scope determined. • Business case developed for project. SYST39409 - Object Oriented Methodologies

8. Unified Process: Elaboration • Basic architecture of the system developed. • Construction plan is approved. • Risks are identified. SYST39409 - Object Oriented Methodologies

9. Unified Process: Construction. • Iterative approach to developing software. • Product will be a beta. SYST39409 - Object Oriented Methodologies

10. Unified Process:Transition • Beta product is introduced to users and information is collected from users during roll-out. SYST39409 - Object Oriented Methodologies

11. Iterative Development Planning Analysis Analysis Analysis Use Cases Design Design Design Test Test Test Implement Implement Implement SYST39409 - Object Oriented Methodologies

12. 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. SYST39409 - Object Oriented Methodologies

13. 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. SYST39409 - Object Oriented Methodologies

14. 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. SYST39409 - Object Oriented Methodologies

15. System Boundary vs Automation Boundary SYST39409 - Object Oriented Methodologies

16. System Boundary vs Automation Boundary SYST39409 - Object Oriented Methodologies

17. Use Case Model • A use case is a script: • A step-by-step description of how a user might make use of the system to do a task • It is a “case of the usage of the system.”

18. User Goals, Events, and Use Cases • Use Case -- An activity the system performs in response to a user request • Techniques for identifying use cases • User goal technique • Each goal at the elementary business process (EBP) level is a use case • EBP – a task performed by one user, in one place in response to a business event, that adds measurable business value, and leaves system and data in consistent state

19. User Goals, Events, and Use Cases (continued) • CRUD analysis technique (create, read, update, delete)‏ • Event decomposition technique

20. Identifying Use Cases Based on User Goals

21. Use Case Based on CRUD Technique

22. CRUD Matrix Example SYST39409-Object Oriented Methodologies

23. Discovering Use Cases • Event – in the real worldEvent occurs when something happens • Events drive or trigger all processing that a system does. • What events occur that will affect the system being studied? • What events occur that will require the system to respond in some way? • Black Box view – focus on “what” not “how” SYST39409-Object Oriented Methodologies

24. Event Decomposition Technique • Event – an occurrence at a specific time and place and which needs to be remembered • Business events trigger elementary business processes (EBPs)‏ • EBPs are at correct level of analysis for use cases • Identify business events to decompose system into activities/use cases

25. Types of Events • External • Outside system • Initiated by external agent or actor • Temporal • Occur as result of reaching a point in time • Based on system deadlines • State • Something inside system triggers processing need

26. Events – (affecting a system)

27. External event checklist SYST39409-Object Oriented Methodologies

28. Temporal Event Checklist SYST39409-Object Oriented Methodologies

29. Listing events • When analyzing a system we must list all events • Identify other information about each of them SYST39409-Object Oriented Methodologies

30. Identifying Events • Can be difficult to determine • Often confused with conditions and responses • May be useful to trace a transaction’s life cycle • Certain events left to design phase • System controls to protect system integrity • Perfect technology assumption defers events

31. Sequence of Actions that Lead Up to Only One Event Affecting the System

32. Sequence of “Transactions” for One Specific Customer Resulting in Many Events

33. Events Deferred Until the Design Phase

34. Event table “Process” Use Case SYST39409-Object Oriented Methodologies

35. Event Table Exercise- Pharmacy System SYST39409 - Object Oriented Methodologies

36. 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 email 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? SYST39409 - Object Oriented Methodologies

37. Use Case - Actors • An actor is always outside the automation boundary of the system but may be partof the manual portion of the system • an actor is not always the same asthe 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. SYST39409 - Object Oriented Methodologies

38. 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 SYST39409 - Object Oriented Methodologies

39. 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 SYST39409 - Object Oriented Methodologies

40. 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? SYST39409 - Object Oriented Methodologies

41. 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 SYST39409 - Object Oriented Methodologies

42. Use Cases • Analysts define use cases at three levels • Brief • Intermediate • Fully developed SYST39409 - Object Oriented Methodologies

43. 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 dispositionand the process terminates with the pharmacist proceeding to the next prescription in the queue. SYST39409 - Object Oriented Methodologies

44. Brief Description of Create New Order Use Case SYST39409 - Object Oriented Methodologies

45. Intermediate Description of Telephone Order Scenario for Create New Order Use Case SYST39409 - Object Oriented Methodologies

46. Fully Developed Description of Telephone Order Scenario for Create New Order Use Case SYST39409 - Object Oriented Methodologies

47. Use Case Narratives- Preconditions & Post Conditions • Hospital Pharmacy Case Study SYST39409-Object Oriented Methodologies

48. Example “Review Prescription” Use Case Fully Developed SYST39409 - Object Oriented Methodologies

49. Use Case Narrative: • Do’s • 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 SYST39409 - Object Oriented Methodologies

50. SYST39409 - Object Oriented Methodologies