Lecture 13: Analysis Modeling

Transcription

1 Lecture 13: Analysis Modeling Software Engineering ITCS 3155 Fall 2008 Dr. Jamie Payton Department of Computer Science University of North Carolina at Charlotte Oct. 16, 2008

2 Announcements Midterms graded 2

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4 Course Letter Grades Exam points = 2*exam grade Exam point cutoffs = 2*exam cutoff Why? To adhere to syllabus: exam is worth ~20% Total point cutoffs = Sum of previous point cutoffs + current point cutoffs 4

5 Lecture Overview Engineering Design Analysis Overview of design analysis Class and object modeling Conceptual modeling 5

6 Software Design Process Software Design Product Design Design Features and Capabilities Design Interactions Problem: Needs, Desires, Constraints Solution: Features and Capabilities Solution: Interactions Engineering Design Create High-Level Design Create Low-Level Design Write Code Solution: SRS Solution: High- Level Design Solution: Low- Level Design Solution: Design Document Solution: Code 6

7 Engineering Design Input: SRS Activities Analysis Design Architectural Design Detailed Design Output: Design document SRS Generic Software Engineering Design SRS : Problem Design Document : Solution Analyze SRS Generate/Improve Candidate Architectures Evaluate Candidate Architectures Select Architecture [else] Finalize Architecture [adequate architecture] Generate/Improve Detailed Design Alternatives Evaluate Detailed Design Alternatives Select Detailed Design [else] Analysis Architectural Design Detailed Design [else] [adequate detailed design] [adequate architecture] Finalize Design Design Document 7

8 Engineering Analysis Breaking down a design problem to enhance understanding SRS serves as foundation for study Aided by use of conceptual models Don t have them? Create them! Want to bring inconsistencies, discrepancies, incompleteness in SRS to light 8

9 Analysis Models An analysis model is a representation of a design problem Captures most important aspects Eliminates consideration of unimportant/impertinent details Analysis modeling approaches Structured analysis Data, operations considered separately Object-oriented analysis 9

10 Analysis Modeling Activity Analysis model elements Conceptual model Static model of important entities Data model Analysis class model (OO modeling) Behavior model Model of dynamic behavior Use cases Data flow models State machine models Sequence diagrams (OO modeling) 10

11 Conceptual Models A conceptual model is a static model Captures important entities in a problem Their responsibilities or attributes The relationships among them Their behaviors Conceptual models help understand the problem, not necessarily describe the solution Capture real-world entities in the problem domain Do not capture software pieces 11

12 Conceptual Modeling with Object-Oriented Concepts: Class Model Conceptual models are sometimes expressed using a class model Representation of classes: in a problem (analysis) in a software solution (design) Class diagrams graphical representations of class models Conceptual Modeling Identify Classes Add Attributes Add Associations Add Multiplicities 12

13 Classes Describes a group of objects with: Person Card Similar properties (attributes) Common behavior (operations Common relationships to other classes Common semantics Jamie Payton Dingxiang Liu Credit card Dingxiang s Visa credit card Drivers license Christine s driver s license 13

14 Objects An entity that makes sense in the problem domain Jamie Payton Evan s driver s license Evan s Homework Assignment 1 All objects have identity and are distinguishable NOT objects: Person Driver s license Homework assignment 14

15 Objects State of North Carolina Driver s License Jamie Payton # University City Blvd DOB: none of your business VISA Jamie Payton /

16 Attributes and Operations Person Objects Card Objects State of North Carolina Driver s License Jamie Payton # University City Blvd DOB: none of your business abstracts to VISA Jamie Payton /2008 Attributes Person Class Attributes name age height weight Operations move change-job Card Class Operations name ID-number expiration-date issue renew 16

17 Class Models Types of class models Analysis class model (conceptual model) Entities in problem Design class model Entities in design Implementation class model Entities in implementation Class models are graphically represented in class diagrams 17

18 Class Diagrams Class-Responsibility-Collaboration (CRC) cards Note cards recording: Classes Responsibilities of classes Collaborations among classes UML Class Diagrams This is what we ll use!!! 18

19 UML Class Diagrams Class Diagram Instance (Object) Diagrams Person age: integer name: String height: double weight: double SSN: integer ELiu: Person age = 25 name= Evan height = 5 8 weight = 160 SSN = BClinton: Person age = 61 name = Bill height = 6.2 weight = 230 SSN = Compartments Class name Attributes Operations Other compartments 19

20 Attribute Specification Format name : type [ multiplicity ] = initial-value Name simple name cannot be suppressed Type any string may be suppressed with the : Initial-value any string may be suppressed along with the = Multiplicity # of values stored in attribute ranges of the form n..k k may be * n..n is the same as n 0..* is the same as * 1 by default if suppressed, square brackets are omitted 20

21 Operation Specification Format Name name(parameter-list ) : return-type-list cannot be suppressed Parameter-list direction param-name : param-type = default-value Direction in, out, inout, return in when suppressed param-name (cannot be suppressed) param-type (cannot be suppressed) default-value (if suppressed, so is =) 21

22 Operation Specification Format name(parameter-list ) : return-type-list return-type-list any comma-separated list of strings if omitted (with :), indicates no return value parameter-list & return-type-list may both be suppressed 22

23 Class Notation Summary ClassName attribute-1: data-type-1 = default-value-1 attribute-2: data-type-2 = default-value-2 operation-1(argument-list-1): result-type-1 operation-2(argument-list-2): result-type-2 23

24 Class Associations Conceptual connection between classes A credit card is issued-by a bank A person works-for a company CreditCard issued-by Bank Person works-for Company Payton: Person works-for UNCC: Company Class diagrams Instance diagrams 24

25 Directional Associations (1) By default, associations are bi-directional Country name: String has-capital City name: String Person name: String is-issued DriversLicense IDNumber: integer 25

26 Directional Associations (2) Associations can be directional Country name: String has-capital City name: String Person name: String is-issued DriversLicense IDNumber: integer 26

27 Multiplicity One object can be related to many objects through the same association Person name: String holds CreditCard CardNumber: integer One person holds one credit card Person holds 0..* CreditCard name: String CardNumber: integer One person holds zero or more credit cards 27

28 Association Multiplicity Multiplicity at the target class end of an association is the number of instances of the target class that can be associated with a single instance of the source class 28

29 Class Diagram Heuristics 1 Naming Classes, attributes, and roles noun phrases Operations and associations verb phrases Other Capitalize class names only Center class and compartment names Left-justify other compartment contents. 29

30 Class Diagram Heuristics 2 Associations Use binary associations whenever possible Prefer association names to rolenames Place association names, rolenames, and multiplicities on opposite sides of the line 30

31 Summary Engineering Design Analysis Create conceptual models Use UML Class diagrams as visual representation of conceptual models UML Class Diagrams Notation Next time Conceptual models Data models Behavioral models Further ahead Good conceptual models translate nicely into design models 31