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Systems Analysis and Design in a Changing World, Fifth Edition

Learn how to identify use cases and define functional requirements using techniques such as user goals, CRUD analysis, and event decomposition. Understand the importance of documenting functional requirements through the creation of models.

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Systems Analysis and Design in a Changing World, Fifth Edition

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  1. Systems Analysis and Design in a Changing World, Fifth Edition

  2. Systems Analysis and Design in a Changing World, 5th Edition Learning Objectives • Explain why identifying use cases is the key to defining functional requirements • Use three techniques for identifying use cases • Write brief, intermediate, and fully developed use case descriptions

  3. Systems Analysis and Design in a Changing World, 5th Edition Learning Objectives (continued)‏ • Explain how the concept of things in the problem domain also defines requirements • Identify and analyze data entities and domain classes needed in the system • Read, interpret, and create an entity-relationship diagram • Read, interpret, and create a domain model class diagram

  4. Systems Analysis and Design in a Changing World, 5th Edition Overview • Document functional requirements bycreatingmodels • Models created during analysis phase activity –Definesystemrequirements • Twoconcepts help identifyfunctionalrequirements in the traditional approach and object-oriented approach • Usecases and the events that trigger them • Things in the users’ work domain

  5. Systems Analysis and Design in a Changing World, 5th Edition User Goals, Events, and Use Cases • UseCase -- An activity the system performs in response to a userrequest • Techniques for identifying use cases • Usergoal technique • Each goal at the elementary business process (EBP) level is a usecase • EBP– a taskperformed by oneuser, in oneplace in response to a businessevent, that adds measurable business value, and leaves system and data in consistent state • CRUDanalysis technique (create, read, update, delete)‏ • Eventdecomposition technique

  6. Systems Analysis and Design in a Changing World, 5th Edition Identifying Use Cases Based on User Goals Figure 5-1

  7. Systems Analysis and Design in a Changing World, 5th Edition Use Case Based on CRUD Technique Figure 5-2

  8. Systems Analysis and Design in a Changing World, 5th Edition Event Decomposition Technique • Event – an occurrence at a specifictime and place and which needs to be remembered • Businesseventstrigger elementary business processes (EBPs)‏ • EBPs are at correct level of analysis for usecases • Identify business events to decomposesystem into activities/usecases

  9. Systems Analysis and Design in a Changing World, 5th Edition Types of Events • External • Outside system • Initiated by externalagent or actor • Temporal • Occur as result of reaching a point in time • Based on system deadlines • State • Something insidesystemtriggersprocessing need

  10. Systems Analysis and Design in a Changing World, 5th Edition Events Affecting a Charge Account Processing System that Lead to Use Cases Figure 5-3

  11. Systems Analysis and Design in a Changing World, 5th Edition External Event Checklist Figure 5-4

  12. Systems Analysis and Design in a Changing World, 5th Edition Temporal Event Checklist Figure 5-5

  13. Systems Analysis and Design in a Changing World, 5th Edition 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

  14. Systems Analysis and Design in a Changing World, 5th Edition Sequence of Actions that Lead Up to Only OneEvent Affecting the System Figure 5-6

  15. Systems Analysis and Design in a Changing World, 5th Edition Sequence of “Transactions” for One Specific Customer Resulting in ManyEvents Figure 5-7

  16. Systems Analysis and Design in a Changing World, 5th Edition Events Deferred Until the Design Phase Figure 5-8

  17. Systems Analysis and Design in a Changing World, 5th Edition Events in the RMO case • Important externalevents involve customers • Customer checks item availability, customer placesorder, customer changes or cancelsorder • Other externalevents involve departments • Shipping fulfillsorder, marketing sendspromotion to customer, merchandising updatescatalog • Temporalevents include periodicreports • Time to produce ordersummaryreports, Time to produce fulfillmentsummaryreports

  18. Systems Analysis and Design in a Changing World, 5th Edition RMO External Events Figure 5-9

  19. Systems Analysis and Design in a Changing World, 5th Edition RMO Temporal Events Figure 5-10

  20. Systems Analysis and Design in a Changing World, 5th Edition Events and Use Cases • EventTable – a catalog of usecaseslistedbyevent. Contains detailed information • Trigger – a signal that indicates an event has occurred • Source – an external agent that initiatesevent and suppliesdata for the event • Response – an output produced by the system • Destination – an external agent that receives the response

  21. Systems Analysis and Design in a Changing World, 5th Edition Information about Each Event in an Event Table Figure 5-11

  22. Systems Analysis and Design in a Changing World, 5th Edition RMO Event Table‏ Figure 5-12

  23. Systems Analysis and Design in a Changing World, 5th Edition DFD Integrates Event Table and ERD Figure 6-5

  24. Systems Analysis and Design in a Changing World, 5th Edition Use Case Descriptions • Use case description – a description of the processing steps for a use case • Actor – a person or thing that uses the system. Actors have contact with the system • Scenario or Instance – a particular set of internal steps that represent a unique path of the use case • Three types of descriptions • Brief description • Intermediate description • Fully developed description

  25. Systems Analysis and Design in a Changing World, 5th Edition Brief Description Figure 5-13

  26. Systems Analysis and Design in a Changing World, 5th Edition Intermediate Description Figure 5-14

  27. Systems Analysis and Design in a Changing World, 5th Edition Fully Developed Description Figure 5-16

  28. Systems Analysis and Design in a Changing World, 5th Edition “Things” in the Problem Domain • Define system requirements by understanding system information that needs to be stored • Store information about things in the problem domain that people deal with when they do their work

  29. Systems Analysis and Design in a Changing World, 5th Edition Types of Things Figure 5-18

  30. Systems Analysis and Design in a Changing World, 5th Edition Procedure for Developing an Initial List of Things • Step 1: Using the event table and information about each use case, identify all nouns • Step 2: Using other information from existing systems, current procedures, and current reports or forms, add items or categories of information needed • Step 3: Refine list and record assumptions or issues to explore • Questions to include it, exclude it, or research it

  31. Systems Analysis and Design in a Changing World, 5th Edition RMO Example “Things” Figure 5-19

  32. Systems Analysis and Design in a Changing World, 5th Edition Characteristics of Things • Relationship • Naturally occurring association among specific things • Occur in two directions • Number of associations is cardinality or multiplicity • Binary, unary, ternary, n-ary • Attribute • One specific piece of information about a thing

  33. Systems Analysis and Design in a Changing World, 5th Edition Relationships Naturally Occur Between Things Figure 5-20

  34. Systems Analysis and Design in a Changing World, 5th Edition Cardinality/Multiplicity of Relationships Figure 5-21

  35. Systems Analysis and Design in a Changing World, 5th Edition Attributes and Values‏ Figure 5-22

  36. Systems Analysis and Design in a Changing World, 5th Edition Data Entities • Things system needs to store data about in traditional IS approach • Modeled with entity-relationship diagram (ERD)‏ • Requirements model used to create the database design model for relational database

  37. Systems Analysis and Design in a Changing World, 5th Edition The Entity-Relationship Diagram (ERD)‏ Figure 5-23

  38. Systems Analysis and Design in a Changing World, 5th Edition Cardinality Symbols of Relationships for ERD Figure 5-24

  39. Systems Analysis and Design in a Changing World, 5th Edition Expanded ERD with Attributes Shown Figure 5-25

  40. Systems Analysis and Design in a Changing World, 5th Edition Customers, Orders, and Order Items Figure 5-26

  41. Systems Analysis and Design in a Changing World, 5th Edition ERD with Many-to-Many Relationship Figure 5-27

  42. Systems Analysis and Design in a Changing World, 5th Edition Many-to-Many Relationship Converted to Associative Entity to Store Grade Attribute Figure 5-28

  43. Systems Analysis and Design in a Changing World, 5th Edition RMO Customer Support System ERD Figure 5-29

  44. Systems Analysis and Design in a Changing World, 5th Edition The Domain Model Class Diagram • Unified Modeling Language (UML) diagram • Domain model class diagram • Models things in the users’ work domain • Used to define requirements for OO (very similar to entities in ERD)‏

  45. Systems Analysis and Design in a Changing World, 5th Edition UML Class Symbol Figure 5-30

  46. Systems Analysis and Design in a Changing World, 5th Edition Simple Domain Model Class Diagram Figure 5-31

  47. Systems Analysis and Design in a Changing World, 5th Edition Simple Domain Model Class Diagram (continued) • No methods shown in domain model • Domain classes are not software classes • Very similar to ERD • UML and domain model can be used in place of ERD in traditional approach

  48. Systems Analysis and Design in a Changing World, 5th Edition Multiplicity of Associations Figure 5-32

  49. Systems Analysis and Design in a Changing World, 5th Edition University Course Enrollment Domain Model Class Diagram Figure 5-33

  50. Systems Analysis and Design in a Changing World, 5th Edition Refined Model with Association Class and Grade Attribute Figure 5-34

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