Object-Oriented Analysis and Design Methods.ppt

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1、TCS2411 Software Engineering,1,Object-Oriented Analysis and Design Methods,“How to create and define objects?”,TCS2411 Software Engineering,2,Lecture Objectives,To understand the process of identifying and creating objects for a system To describe a method for developing objects for an object-orient

2、ed system To describe the representations that can be used for objects and their relationships To discuss the dynamic aspects of object-oriented systems and how to model them,TCS2411 Software Engineering,3,Too Many Methodologies!,Booch Object-Oriented Design Rumbaugh Object Modeling Technique Shlaer

3、 and Mellor Analysis and Design Jacobson Objectory Wirfs-Brock Responsibility Driven Design Martin and Odell Object-Oriented Analysis and Design Others,TCS2411 Software Engineering,4,Object-Oriented Analysis,Identify the objects and classes Identify the object attributes Identify operations on objec

4、ts and classes Define object and class relationships Model dynamic concepts,TCS2411 Software Engineering,5,Identify the objects and classes,Grammatical Analysis Nouns are objects and attributes Verbs are operations or services Tangible entities (things), roles, events, interactions, etc. in applicat

5、ion domain Use behavioural approach Participants in behaviours as objects Scenario-based analysis,TCS2411 Software Engineering,6,Identify the object attributes,Specify attributes (instance variables) of objects in problem domain These are to be recorded, displayed, stored, and/or manipulated in func

6、tions of the domain,TCS2411 Software Engineering,7,Identify operations on objects and classes,Operations that are used to interact with the objects and classes Each class has a protocol that captures the messages or operations that could be handled by the class or its instances Users or “clients” of

7、 classes and objects deal primarily with the external operations of the class,TCS2411 Software Engineering,8,Example Scenario,“The Office Information Retrieval System (OIRS) can file documents under some name in one or more indexes, retrieve documents, display and maintain document indexes, archive

8、documents and destroy documents. The system is activated by a request from the user and always returns a message to the user indicating the success or failure of the request.”,TCS2411 Software Engineering,9,Objects Identified,IndexNameDisplay Delete entry Add entry,UserGet command Put message,Docume

9、ntNameFileRetrieveArchiveDestroy,Retrieval SystemUser command,TCS2411 Software Engineering,10,Define object and class relationships,Capture relationship between classes. Typical relationships: Inheritance Organisation of classes or entity types in problem domain One-to-One, One-to-Many, Many-to-Many

10、 relationships that exist between objects that reference each other,TCS2411 Software Engineering,11,Example of Inheritance,Person,Student,Employee,MarketingPerson,SalesPerson,SalesManager,TCS2411 Software Engineering,12,Example of Other Relationships,Country,City,Person,Company,File,User,Has-capital

11、,Works-for,Accessible-by,One-to-One,One-to-Many,Many-to-Many,TCS2411 Software Engineering,13,Model dynamic concepts,State transition diagrams Specify states of the objects Specify events that trigger transitions Specify actions taken due to transitions Data flow diagrams Describe flow of objects and

12、 information Timing diagrams Illustrate object interactions over time,TCS2411 Software Engineering,14,State transition diagram,Blacks turn,Whites turn,Start,Black moves,White moves,checkmate,checkmate,stalemate,stalemate,Draw,White wins,Black wins,TCS2411 Software Engineering,15,Data flow diagram,Cu

13、stomer,Update,Verify,Account,password,amount,cash,Coded password,old balance,Password ok,new balance,TCS2411 Software Engineering,16,Timing diagrams,Caller,Phone line,Callee,Caller lifts receiver,Dial tone begins,Dials number,Ringing tone,Phone rings,Answers phone,Tone stops,Ringing stops,Phones con

14、nected,Phones connected,Callee hangs up,Connection broken,Connection broken,TCS2411 Software Engineering,17,Unified Modeling Language Approach OOA,User view model system represented from the users perspective by developing use-case model Structural view model data and function is view from inside th

15、e system, static structure (classes, objects, relationships) is modeled,TCS2411 Software Engineering,18,Use Case,Scenario based technique for requirement elicitation Use case should achieve the following objectives : Define functional and operational requirements of the system Provide clear descript

16、ion of how end user and the system will interact with one another Basis for validation testing,TCS2411 Software Engineering,19,Use Case Diagram Elements,Actor : Entities that interact with the system Person, machine, another system etc Represent roles that a user play in the system Use case Sequence

17、 of transaction performed by the system Initiated by an actor to invoke certain function in the system,TCS2411 Software Engineering,20,Use Case Diagram For The Library,TCS2411 Software Engineering,21,Identify Objects and Classes,Object Thing that can interact with Reacts when send messages concept,

18、abstraction or thing that has sharp boundaries and meaning for an application Object has State : value of property at a given time Behavior : objects action and reaction Identity : distinguishes from other objects,Class A sets of objects with an equivalent roles in the system Every object belongs to

19、 a class Example : Tangible : book, copy, course Roles : library member, student Events : arrival, leaving, request Interaction : meeting, intersection,TCS2411 Software Engineering,22,Identify Class Attributes & Operations,TCS2411 Software Engineering,23,Relationship,Why do we need Relationship All

20、system encompass many classes and objects Objects contribute to the behavior of a system by collaborating with one another Collaboration is accomplish through relationships Two important type of relationship during analysis Association Aggregation,TCS2411 Software Engineering,24,Association,Represen

21、t relationship between objects of classes Multiplicity Association Number of instance of one class related to one instance of the other class Multiplicity indicator Many - * Exactly one - 1 Zero or more - 0 * One or more - 1 * Zero or one - 0 1 Specified range - m n Eg :- 2 4,TCS2411 Software Engine

22、ering,25,Inheritance,Hierarchy abstraction where subclass inherits from one or more superclass Subclass inherits attributes, operations and relationships Subclass may have additional attributes, operations or relationship How to find inheritance? Look for common behavior and attributes in classes,TC

23、S2411 Software Engineering,26,Aggregation,Known as part-of relationship A whole class related to its parts Association or Aggregation ? If two object tightly bound by a whole part relationship : Aggregation If two object considered independent even though they are often linked : Association,TCS2411

24、Software Engineering,27,Example of Aggregation,TCS2411 Software Engineering,28,Object Interactions,To show dynamic behavior of the system Also known as Sequence Diagram Interaction between objects is modeled using interaction diagram. Show how messages passed between objects Realize use cases,TCS241

25、1 Software Engineering,29,Object Interactions(Continued),TCS2411 Software Engineering,30,Changes In System : State Diagram,State of book object may change when a copy of book is successfully book borrowable not borrowable,There is a copy available in the library,All copies are out on loan or reserve

26、d,TCS2411 Software Engineering,31,Deliverables from Unified Modeling Language Approach OOA,Use Case Diagram Sequence Diagram Class Diagram State Transition Diagram,TCS2411 Software Engineering,32,Object-Oriented Design,Detailed specifications of the following: Subsystems or class categories Partitio

27、ning the system, providing interfaces, interactions, and mapping to targeted system Class definitions structure or representation behaviour or operations implementation algorithms additional support classes for implementation,TCS2411 Software Engineering,33,Object-Oriented Design (Continued),Class r

28、elationships Containment Referencing Aggregation Inheritance Object diagrams and object relationships Descriptions of how objects interact Class interaction - what classes are used by another class,TCS2411 Software Engineering,34,Object-Oriented Design (Continued),State transition Extends state tran

29、sition diagrams in analysis Timing diagrams Extends timing diagrams in analysis Designing algorithms implementation algorithms and logic Physical compilation units Compilation modules, interface specifications,TCS2411 Software Engineering,35,UML Approach to OOD,TCS2411 Software Engineering,36,System

30、 Design,Partition the Analysis Model Refine analysis objects using inheritance, pattern and encapsulation Package into subsystem or modules Can be characterized by responsibility Design artifact may include Refined class diagram Interaction, activity component & deployment diagram State models Compo

31、sed classes into packages. Composition can be done base on Use cases Unit of physical realization Processing,TCS2411 Software Engineering,37,System Design (continued),Concurrency and Subsystem AllocationAssign concurrency if classes are active at the same time Implement on the same processor hardwar

32、e Concurrent is defined by examining the state diagram Establish thread for active object Thread control continues when it sends message to another object and wait for responses Isolate these thread controls Consider performance, cost and overhead by processor when allocates the object to the proces

33、sor,TCS2411 Software Engineering,38,System Design (Continued),Task Management Component How the task initiated Common Event driven Interrupt from outside source (Processor, sensor etc) Clock driven Interrupt from system clock Determine the task priority and criticality High priority task must have i

34、mmediate access to the resources High critical task must operate continually even if resources availability is reduced or system operates in degrade state.,TCS2411 Software Engineering,39,System Design (continued),User Interface Component Define system menu and sub functions available for the menu D

35、ata Management Component Data management for critical application Layered design Creation of infrastructure for storage and retrieval Use database, files, shared memory Design the attribute and operation to manage data Resource Management Component Subsystem may compete to use the same resources at

36、the same time,TCS2411 Software Engineering,40,System Design (continued),User Interface Component Define system menu and sub functions available for the menu Data Management Component Data management for critical application Layered design Creation of infrastructure for storage and retrieval Use data

37、base, files, shared memory Design the attribute and operation to manage data Resource Management Component Subsystem may compete to use the same resources at the same time,TCS2411 Software Engineering,41,Activity Diagram,Activity diagram Activities coordination To show how an operation can be implem

38、ented Useful when an operation has to achieve a number of different things Record dependencies between activities Which thing can happen in parallel What must finished first before something else can start,TCS2411 Software Engineering,42,Activity Diagram,TCS2411 Software Engineering,43,Object Design

39、,Object Description Establish object interface Define message the object can receive Operation the object can perform when it receives the message Implementation details Objects private parts Internal details about data structure Details about the operation Algorithms and Data Structure Algorithm cr

40、eated to implements operation specification,TCS2411 Software Engineering,44,Component Model,Component Standard building unit that is used to develop an application Types of component Source code (e.g: file containing code of the class) Has to be available when compiled Binary object code (e.g: class

41、 library) Depends on any object code Must be linked to form an executable program Executable application (e.g: the client/server, database manager) May depend on other executable programs to interact at runtime,TCS2411 Software Engineering,45,A component diagram showing compile time dependencies,TCS

42、2411 Software Engineering,46,Deployment Model,Deployment diagram shows Physical communication links between hardware items Machines, printers and other resources Relationship between physical machines and processes What runs where,TCS2411 Software Engineering,47,Deliverables from UML Approach to OOD

43、,Class Diagram (Refined) State Transition Diagram (Refined) Component Diagram Deployment Diagram,TCS2411 Software Engineering,48,References,“Software Engineering: A Practitioners Approach” 5th Ed. by Roger S. Pressman, Mc-Graw-Hill, 2001 “Object-Oriented Modeling and Design” by James Rumbaugh et al,

44、 Prentice Hall, 1991 “Object Orientation” by Setrag Khoshafian & Razmik Abnous, John Wiley & Sons, 1995 “Teach Your Self UML in 24 hours” by Joseph Schmuller, Sams Publication, 2001 “Mastering UML with Rational Rose” by Wendy Boggs and Michael Boggs, Sybex Inc, 2000 “Using UML Software Engineering With Objects and Components” by Perdita Stevens, Rob Pooley, Addison Wesley, 2000,