ISE-VII-OBJECT-ORIENTED MODELING AND DESIGN [10CS71]-NOTES - Object Oriented Modeling and Design 10CS71 OBJECT ORIENTED MODELING AND DESING Subject Code

ISE-VII-OBJECT-ORIENTED MODELING AND DESIGN [10CS71]-NOTES...

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Unformatted text preview: Object Oriented Modeling and Design 10CS71 OBJECT ORIENTED MODELING AND DESING Subject Code: 10CS71 Hours/Week : 04 Total Hours : 52 I.A. Marks : 25 Exam Hours: 03 Exam Marks: 100 PART - A UNIT - 1 7 H o ur s INTRODUCTION, MODELING CONCEPTS, CLASS MODELING: What is Object Orientation? What is OO development? OO themes; Evidence for usefulness of OO development; OO modeling history. Modeling as Design Technique: Modeling; abstraction; The three models. Class Modeling: Object and class concepts; Link and associations concepts; Generalization and inheritance; A sample class model; Navigation of class models; Practical tips. UNIT - 2 6 H o ur s ADVANCED CLASS MODELING, STATE MODELING: Advanced object and class concepts; Association ends; N-ary associations; Aggregation; Abstract classes; Multiple inheritance; Metadata; Reification; Constraints; Derived data; Packages; Practical tips. State Modeling: Events, States, Transitions and Conditions; State diagrams; State diagram behavior; Practical tips. UNIT - 3 6 H o ur s ADVANCED STATE MODELING, INTERACTION MODELING: Advanced State Modeling: Nested state diagrams; Nested states; Signal generalization; Concurrency; A sample state model; Relation of class and state models; Practical tips. Interaction Modeling: Use case models; Sequence models; Activity models. Use case relationships; Procedural sequence models; Special constructs for activity models. UNIT - 4 7 Hours PROCESS OVERVIEW, SYSTEM CONCEPTION, DOMAIN ANALYSIS: Process Overview: Development stages; Development life cycle. System Conception: Devising a system concept; Elaborating a concept; Preparing a problem statement. Domain Analysis: Overview of anal ysis; Domain class model; Domain state model; Domain interaction model; Iterating the analysis. PART - B UNIT - 5 7 H o ur s APPLICATION ANALYSIS, SYSTEM DESIGN: Application Analysis: Application interaction model; Application class model; Application state model; Adding operations. Overview of system design; Estimating performance; Making a reuse plan; Breaking a system in to sub-systems; Identifying concurrency; Allocation of sub-systems; Management of data storage; Handling global resources; Choosing a Dept. of ISE, SJBIT Pag e 1 Object Oriented Modeling and Design 10CS71 software control strategy; Handling boundary conditions; Setting the trade-off priorities; Common architectural styles; Architecture of the ATM system as the example. UNIT - 6 7 H o ur s CLASS DESIGN, IMPLEMENTATION MODELING, LEGACY SYSTEMS: Class Design: Overview of class design; Bridging the gap; Realizing use cases; Designing algorithms; Recursing downwards, Refactoring; Design optimization; Reification of behavior; Adjustment of inheritance; Organizing a class design; ATM example. Implementation Modeling: Overview of implementation; Fine-tuning classes; Fine-tuning generalizations; Realizing associations; Testing. Legacy Systems: Reverse engineering; Building the class models; Building the interaction model; Building the state model; Reverse engineering tips; Wrapping; Maintenance. UNIT - 7 6 H o ur s DESIGN PATTERNS – 1: What is a pattern and what makes a pattern? Pattern categories; Relationships between patterns; Pattern description. Communication Patterns: Forwarder-Receiver; Client-Dispatcher-Server; PublisherSubscriber. UNIT - 8 6 H o ur s DESIGN PATTERNS – 2, IDIOMS: Management Patterns: Command processor; View handler. Idioms: Introduction; What can idioms provide? Idioms and style; Where to find idioms; Counted Pointer example. TEXT BOOKS: Text Books: 1. Michael Blaha, James Rumbaugh: Object-Oriented Modeling and Design with UML, 2nd Edition, Pearson Education, 2005. (Chapters 1 to 17, 23) 2. Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, Michael Stal: Pattern-Oriented Software Architecture, A System of Patterns, Volume 1, John Wiley and Sons, 2007. (Chapters 1, 3.5, 3.6, 4) Reference Books: 1. Grady Booch et al: Object-Oriented Anal ysis and Design with Applications, 3rd Edition, Pearson Education, 2007. 2. Brahma Dathan, Sarnath Ramnath: Object-Oriented Analysis, Design, and Implementation, Universities Press, 2009. 3. Hans-Erik Eriksson, Magnus Penker, Brian Lyons, David Fado: UML 2 Toolkit, Wiley- Dreamtech India, 2004. 4. Simon Bennett, Steve McRobb and Ray Farmer: Object-Oriented Systems Analysis and Design Using UML, 2nd Edition, Tata McGraw-Hill, 2002. Dept. of ISE, SJBIT Pag e 2 Object Oriented Modeling and Design 10CS71 INDEX SHEET P A RT A : UNIT 1: INTRODUCTION, MODELING Page no. 4 -31 CONCEPTS, CLASS MODELING: UNIT 2: ADVANCED CLASS MODELING, 32 – 49 STATE MODELING UNIT 3: ADVANCED STATE MODELING, 50 – 79 INTERACTION MODELING UNIT 4: PROCESS OVERVIEW, SYSTEM 80 – 83 CONCEPTION, DOMAIN ANALYSIS PART – B UNIT 5: APPLICATION ANALYSIS, SYSTEM Page no. 84 – 112 DESIGN UNIT 6: CLASS DESIGN, IMPLEMENTATION 113 – 127 MODELING, LEGACY SYSTEMS UNIT 7: DESIGN PATTERNS – 1 128 – 145 UNIT 8: DESIGN PATTERNS – 2, IDIOMS 146 - 162 Dept. of ISE, SJBIT Pag e 3 Object Oriented Modeling and Design 10CS71 Unit1: INTRODUCTION, MODELING CONCEPTS, CLASS MODELING: Syllabus • • • • • • • • • • • • • • --- 7 h r W hat is object orientation? W hat is oo development? Oo themes Evidence for usefulness of oo development Oo modeling history Modeling Abstraction The tree models Objects and class concepts Link and association concepts Generalization and inheritance A sample class model Navigation of class models Practical tips INTRODUCTION Note 1: Intention of this subject (object oriented modeling and design) is to learn how to apply object -oriented concepts to all the stages of the software development life cycle. Note 2: Object-oriented modeling and design is a way of thinking about problems using models organized around real world concepts. The fundamental construct is the object, which combines both data structure and behavior. WHAT IS OBJECT ORIENTATION? �D efinition: OO means that we organize software as a collection of discrete objects (that incorporate both data structure and behavior). �There are four aspects (characteristics) required by an OO approacho Identity. • Classification. • Inheritance. • Polymorphism. �I dentity: • Identity means that data is quantized into discrete, distinguishable entities called objects. • E.g. for objects: personal computer, bicycle, queen in chess etc. Dept. of ISE, SJBIT Pag e 4 Object Oriented Modeling and Design 10CS71 • Objects can be concrete (such as a file in a file system) or conceptual (such as scheduling policy in a multiprocessing OS). Each object has its own inherent identity. (i.e two objects are distinct even if all their attribute values are identical). • In programming languages, an object is referenced by a unique handle. �C lassification: • Classification means that objects with the same data structure (attribute) and behavior (operations) are grouped into a class. • E.g. paragraph, monitor, chess piece. • Each object is said to be an instance of its class. • Fig below shows objects and classes: Each class describes a possibly infinite set of individual objects. Inheritance: • It is the sharing of attributes and operations (features) among classes based on a hierarchical relationship. A super class has general information that sub classes refine and elaborate. • E.g. Scrolling window and fixed window are sub classes of window. �P olymorphism: • Polymorphism means that the same operation may behave differently for different classes. • For E.g. move operation behaves differently for a pawn than for the queen in a chess game. Dept. of ISE, SJBIT Pag e 5 Object Oriented Modeling and Design 10CS71 Note: An operation is a procedure/transformation that an object performs or is subjected to. An implementation of an operation by a specific class is called a method. WHAT IS OO DEVELOPMENT? �D evelopment refers to the software life cycle: Analysis, Design and Implementation. The essence of OO Development is the identification and organization of application concepts, rather than their final representation in a programming language. It’s a conceptual process independent of programming languages. OO development is fundamentally a way of thinking and not a programming technique. OO methodology �Here we present a process for OO development and a graphical notation for representing OO concepts. The process consists of building a model of an application and then adding details to it during design. he methodology has the following stages �T • System conception: Software development begins with business analysis or users conceiving an application and formulating tentative requirements. • Analysis: The analyst scrutinizes and rigorously restates the requirements from the system conception by constructing models. The analysis model is a concise, precise abstraction of what the desired system must do, not how it will be done. • The analysis model has two parts- Dept. of ISE, SJBIT Pag e 6 Object Oriented Modeling and Design 10CS71 • � Domain Model- a description of real world objects reflected within the system. • � Application Model- a description of parts of the application system itself that are visible to the user. • E.g. In case of stock broker application• Domain objects may include- stock, bond, trade & commission. • Application objects might control the execution of trades and present the results. • System Design: The development teams devise a high-level strategy- The System Architecture- for solving the application problem. The system designer should decide what performance characteristics to optimize, chose a strategy of attacking the problem, and make tentative resource allocations. • Class Design: The class designer adds details to the analysis model in accordance with the system design strategy. His focus is the data structures and algorithms needed to implement each class. • Implementation: Implementers translate the classes and relationships developed during class design into a particular programming language, database or hardware. During implementation, it is important to follow good software engineering practice. Three models �We use three kinds of models to describe a system from different view points. 1. Class Model—for the objects in the system & their relationships. It describes the static structure of the objects in the system and their relationships. Class model contains class diagrams- a graph whose nodes are classes and arcs are relationships among the classes. 2. State model—for the life history of objects. It describes the aspects of an object that change over time. It specifies and implements control with state diagrams-a graph whose nodes are states and whose arcs are transition between states caused by events. 3. Interaction Model—for the interaction among objects. It describes how the objects in the system co-operate to achieve broader results. This model starts with use cases that are then elaborated with sequence and activity diagrams. Use case – focuses on functionality of a system – i.e what a system does for users. Sequence diagrams – shows the object that interact and the time sequence of their interactions. Activity diagrams – elaborates important processing steps. OO THE M ES Dept. of ISE, SJBIT Pag e 7 Object Oriented Modeling and Design 10CS71 Several themes pervade OO technology. Few are – 1. Abstraction Abstraction lets you focus on essential aspects of an application while ignoring details i.e focusing on what an object is and does, before deciding how to implement it. It’s the most important skill required for OO development. 2. Encapsulation (information hiding) It separates the external aspects of an object (that are accessible to other objects) from the internal implementation details (that are hidden from other objects) Encapsulation prevents portions of a program from becoming so interdependent that a small change has massive ripple effects. 3. Combining data and behavior Caller of an operation need not consider how many implementations exist. In OO system the data structure hierarchy matches the operation inheritance hierarchy (fig). 4. Sharing • OO techniques provide sharing at different levels. • Inheritance of both data structure and behavior lets sub classes share common code. • OO development not only lets you share information within an application, but also offers the prospect of reusing designs and code on future projects. 5. Emphasis on the essence of an object • OO development places a greater emphasis on data structure and a lesser emphasis on procedure structure than functional-decomposition methodologies. 6. Synergy • Identity, classification, polymorphism and inheritance characterize OO languages. Dept. of ISE, SJBIT Pag e 8 Object Oriented Modeling and Design 10CS71 • Each of these concepts can be used in isolation, but together they complement each other synergistically. MODELLING AS A DESIGN TECHNIQUE Note: A model is an abstraction of something for the purpose of understanding it before building it. MO D E L L I N G �Designers build many kinds of models for various purposes before constructing things. �Models serve several purposes – Testing a physical entity before building it: Medieval built scale models of Gothic Cathedrals to test the forces on the structures. Engineers test scale models of airplanes, cars and boats to improve their dynamics. Communication with customers: Architects and product designers build models to show their customers (note: mock-ups are demonstration products that imitate some of the external behavior of a system). Visualization: Storyboards of movies, TV shows and advertisements let writers see how their ideas flow. Reduction of complexity: Models reduce complexity to understand directly by separating out a small number of important things to do with at a time. ABSTRACTION �A bstraction is the selective examination of certain aspects of a problem. �T he goal of abstraction is to isolate those aspects that are important for some purpose and suppress those aspects that are unimportant. THE THREE MODELS 1. Class Model: represents the static, structural, “data” aspects of a system. • It describes the structure of objects in a system- their identity, their relationships to other objects, their attributes, and their operations. • Goal in constructing class model is to capture those concepts from the real world that are important to an application. • Class diagrams express the class model. 2. State Model: represents the temporal, behavioral, “control” aspects of a system. • State model describes those aspects of objects concerned with time and the sequencing of operations – events that mark changes, states that define the context for events, and the organization of events and states. • State diagram express the state model. • Each state diagram shows the state and event sequences permitted in a system for one class of objects. • State diagram refer to the other models. Dept. of ISE, SJBIT Pag e 9 Object Oriented Modeling and Design 10CS71 • Actions and events in a state diagram become operations on objects in the class model. References between state diagrams become interactions in the interaction model. 3. Interaction model – represents the collaboration of individual objects, the “interaction” aspects of a system. • Interaction model describes interactions between objects – how individual objects collaborate to achieve the behavior of the system as a whole. • The state and interaction models describe different aspects of behavior, and you need both to describe behavior fully. • Use cases, sequence diagrams and activity diagrams document the interaction model. CLASS MODELLING Note: A class model captures the static structure of a system by characterizing the objects in the system, the relationships between the objects, and the attributes and operations for each class of objects. OBJECT AND CLASS CONCEPT O bje c ts �Purpose of class modeling is to describe objects. �An object is a concept, abstraction or thing with identity that has meaning for an application. Ex: Joe Smith, Infosys Company, process number 7648 and top window are objects. Classes �An object is an instance or occurrence of a class. �A class describes a group of objects with the same properties (attributes), behavior (operations), kinds of relationships and semantics. Ex: Person, company, process and window are classes. Note: All objects have identity and are distinguishable. Two apples with same color, shape and texture are still individual apples: a person can eat one and then the other. The term identity means that the objects are distinguished by their inherent existence and not by descriptive properties that they may have. Dept. of ISE, SJBIT Pag e 1 0 Object Oriented Modeling and Design 10CS71 CL AS S M O D E LLI N G • OBJECT AND CLASS CONCEPT • An object has three characteristics: state, behavior and a unique identification. or • An object is a concept, abstraction or thing with identity that has meaning for an application. Eg: • Note: The term id e n t it y m e a n s t h a t t h e o b je c t s a r e d is t in g u i s h e d b y t h e ir in h e r e n t e x i s t e n c e a n d n o t b y d e s c r ip t iv e p r o p e r t ie s t h a t t h e y may have. Class diagrams �C lass diagrams provide a graphic notation for modeling classes and their relationships, thereby describing possible objects. Note: An object diagram shows individual objects and their relationships. Useful for documenting test cases and discussing examples. �Class diagrams are useful both for abstract modeling and for designing actual programs. Note: A class diagram corresponds to infinite set of object diagrams. �F igure below shows a class (left) and instances (right) described by it. �C onventions used (UML): • UML symbol for both classes and objects is box. • Objects are modeled using box with object name followed by colon followed by class name. • Use boldface to list class name, center the name in the box and capitalize the first letter. Use singular nouns for names of classes. • To run together multiword names (such as JoeSmith), separate the words with • intervening capital letter. Values and Attributes: �V alue is a piece of data. Dept. of ISE, SJBIT Pag e 1 1 Object Oriented Modeling and Design 10CS71 Attribute is a named property of a class that describes a value held by each object of the class. � F o l l o w i n g a n a l o g y h o l d s : Object is to class as value is to attribute. �E.g. Attributes: Name, bdate, weight. Values: JoeSmith, 21 October 1983, 64. (Of person object). �Fig shows modeling notation �C onventions used (UML): • List attributes in the 2nd compartment of the class box. Optional details (like default value) may follow each attribute. • A colon precedes the type, an equal sign precedes default value. • Show attribute name in regular face, left align the name in the box and use small case for the first letter. �S imilarly we may also include attribute values in the 2nd compartment of object boxes with same conventions. Note: Do not list object identifiers; they are implicit in models. E.g. An operation is a function or procedure that maybe applied to or by objects in a class. E.g. Hire, fire and pay dividend are operations on Class Company. Open, close, hide and redisplay are operations on class window. �A method is the implementation of an operation for a class. E.g. In class file, print is an operation you could implement different methods to print files. �N ote: Same operation may apply to many different classes. Such an operation is polymorphic. �Fig shows modeling notation. Dept. of ISE, SJBIT Pag e 1 2 Object Oriented Modeling and Design 10CS71 �U ML conventions used – • List operations in 3rd compartment of class box. • List operation name in regular face, left align and use lower case for first letter. • Optional details like argument list and return type may follow each operation name. • Parenthesis enclose an argument list, commas separate the arguments. A colon precedes the resul...
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