The document discusses various techniques for modeling software requirements including: 1) Entity-relationship diagrams (ERDs) which model data objects and their relationships to understand the data domain. 2) Use case modeling which describes scenarios of how external actors will use the system through use cases and diagrams. 3) Flow-oriented modeling using data flow diagrams (DFDs) which represent how data objects are transformed as they move through the system.

1. Software Engineering: A Practitioner’s Approach, 6/e Chapter 8 Analysis Modeling copyright © 1996, 2001, 2005 R.S. Pressman & Associates, Inc. For University Use Only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioner's Approach. Any other reproduction or use is expressly prohibited.

3. Fig8.1 Analysis model as A Bridge 需求 分析 設計

9. 8.3.1 What is a Data Object? each instance of an object (e.g., a book) can be identified uniquely (e.g., ISBN #) each plays a necessary role in the system i.e., the system could not function without access to instances of the object each is described by attributes that are themselves data items Object — something that is described by a set of attributes (data items) and that will be manipulated within the software (system)

10. Typical Objects external entities (printer, user, sensor) things (e.g, reports, displays, signals) occurrences or events (e.g., interrupt, alarm) roles (e.g., manager, engineer, salesperson) organizational units (e.g., division, team) places (e.g., manufacturing floor) structures (e.g., employee record)

11. 8.3.2 Data Objects and Attributes A data object contains a set of attributes that act as an aspect, quality, characteristic, or descriptor of the object object: automobile attributes: make model body type price options code

13. 8.3.3 ERD (Entity Relational Diagram) Notation (0, m) (1, 1) object object relationship 1 2 One common form: (0, m) (1, 1) object 1 object 2 relationship Another common form: attribute

15. The ERD: An Example (1,1) (1,m) places Customer request for service generates (1,n) (1,1) work order work tasks materials consists of lists (1,1) (1,w) (1,1) (1,i) selected from standard task table (1,w) (1,1)

18. Building a Class

19. What is a Class? external entities things occurrences roles organizational units places structures class name attributes: operations:

20. Encapsulation/Hiding The object encapsulates both data and the logical procedures required to manipulate the data Achieves “information hiding” method # 1 data method # 2 method # 4 method # 5 method # 6 method # 3

21. Class Hierarchy Chair Table Desk ” Chable" instances of Chair PieceOfFurniture (superclass) subclasses of the

22. Methods (a.k.a. Operations, Services) An executable procedure that is encapsulated in a class and is designed to operate on one or more data attributes that are defined as part of the class. A method is invoked via message passing.

26. Fig 8.6 Use-Case Diagram

27. Fig 8.7 Activity Diagram Supplements the use-case by providing a diagrammatic representation of procedural flow

28. Fig 8.8 Swimlane Diagrams Allows the modeler to represent the flow of activities described by the use-case and at the same time indicate which actor (if there are multiple actors involved in a specific use-case) or analysis class has responsibility for the action described by an activity rectangle

29. 8.6 Flow-Oriented Modeling Represents how data objects are transformed at they move through the system A data flow diagram (DFD) is the diagrammatic form that is used Considered by many to be an ‘old school’ approach, flow-oriented modeling continues to provide a view of the system that is unique—it should be used to supplement other analysis model elements

30. The Flow Model Every computer-based system is an information transform .... computer based system input output

31. Flow Modeling Notation external entity process data flow data store

32. External Entity A producer or consumer of data Examples: a person, a device, a sensor Another example: computer-based system Data must always originate somewhere and must always be sent to something

33. Process A data transformer (changes input to output) Examples: compute taxes, determine area, format report, display graph Data must always be processed in some way to achieve system function

34. Data Flow Data flows through a system, beginning as input and be transformed into output. compute triangle area base height area

35. Data Stores Data is often stored for later use. look-up sensor data sensor # report required sensor #, type, location, age sensor data sensor number type, location, age

38. Level 0 DFD Example user processing request video source NTSC video signal digital video processor requested video signal monitor

40. The Data Flow Hierarchy P a b x y p1 p2 p3 p4 5 a b c d e f g level 0 level 1

42. 8.6.4 Process Specification (PSPEC) PSPEC narrative pseudocode (PDL) equations tables diagrams and/or charts bubble

43. DFDs: A Look Ahead Maps into analysis model design model

45. The Control Model the control flow diagram is "superimposed" on the DFD and shows events that control the processes noted in the DFD control flows—events and control items—are noted by dashed arrows a vertical bar implies an input to or output from a control spec (CSPEC) — a separate specification that describes how control is handled a dashed arrow entering a vertical bar is an input to the CSPEC a dashed arrow leaving a process implies a data condition a dashed arrow entering a process implies a control input read directly by the process control flows do not physically activate/deactivate the processes—this is done via the CSPEC

46. Control Specification (CSPEC) The CSPEC can be: state diagram (sequential spec) state transition table decision tables activation tables combinatorial spec

47. Guidelines for Building a CSPEC list all sensors that are "read" by the software list all interrupt conditions list all "switches" that are actuated by the operator list all data conditions recalling the noun-verb parse that was applied to the software statement of scope, review all "control items" as possible CSPEC inputs/outputs describe the behavior of a system by identifying its states; identify how each state is reach and defines the transitions between states focus on possible omissions ... a very common error in specifying control, e.g., ask: "Is there any other way I can get to this state or exit from it?"

50. Selecting Classes—Criteria needed services multiple attributes common attributes common operations essential requirements retained information

51. Fig 8.13 Class Diagram Class name attributes operations

52. Fig 8.14 Class Diagram (UML)

54. Fig 8.15 CRC Modeling

58. fig 8.16 Composite Aggregate Class

61. Multiplicity

62. Dependencies (Ex. SJSMIT 校園即時景觀 )

64. 8.19 Analysis Packages

67. Fig 8.20 State Diagram for the ControlPanel Class

70. Fig 8.21 Sequence Diagram

71. Writing the Software Specification Everyone knew exactly what had to be done until someone wrote it down!

72. Specification Guidelines

73. Specification Guidelines

74. Specification Guidelines