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Software Engineering

Learn how object-oriented analysis can be used to describe an information system. Understand object modeling terms and concepts, such as objects, instances, attributes, methods, messages, and classes. Explore the use of Unified Modeling Language (UML) for visualizing, specifying, constructing, and documenting software systems.

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Software Engineering

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  1. Software Engineering - Mr. Ahmad Al-Ghoul

  2. Chapter Objectives • Explain how object-oriented analysis can be used to describe an information system • Define object modeling terms and concepts, including objects, instances, attributes, methods, messages, and classes

  3. Introduction • Object-oriented (O-O) analysis describes an information system by identifying things called objects. Object-oriented analysis is a popular approach that sees a system from the viewpoint of the objects themselves as they function and interact with the system. • Although traditional structured analysis is the most popular approach, the use of object-oriented analysis and design is growing rapidly

  4. Object-Oriented analysis and design using UML • The Unified Modeling Language (UML) is used to describe the system concept as a collection of objects incorporating both data and processes • UML is just a standard diagramming notation. It is just a tool, not a skill that is valuable in itself.

  5. Object-Oriented analysis and design using UML • The UML combines the best of the best from • Data Modelling concepts (Entity Relationship Diagrams) • Business Modelling (work flow) • Object Modelling • Component Modelling • The UML is the standard language for visualizing, specifying, constructing, and documenting the artefacts of a software-intensive system • It can be used with all processes, throughout the development life cycle, and across different implementation technologies

  6. Object-Oriented analysis and design using UML • The UML may be used to: • Display the boundary of a system & its major functions using use cases and actors • Illustrate use case realizations with interaction diagrams • Represent a static structure of a system using class diagrams • Model the behaviour of objects with state transition diagrams • Reveal the physical implementation architecture with component & deployment diagrams

  7. Object-Oriented analysis and design using UML • Object-Oriented Terms and Concepts • Object model • An object model describes objects, which combine data and processes. Object models are the end product of object-oriented analysis.

  8. Object-Oriented analysis and design using UML • Object-Oriented Terms and Concepts • Objects • Instances • Attributes • Methods • Messages • Classes

  9. Object-Oriented analysis and design using UML • Objects and Instances • An object represents a real person, place, event, or transaction that are relevant to the system we are analyzing. • An object includes data and the processes that affect that data • An object has certain attributes, which are characteristics that describe the object. • An object has methods, which are tasks or functions that the object performs when it receives a message, or command. • A group of similar objects are called class • The UML represents an object as a rectangle with the object name at top, followed by the object’s attributes and methods • An instance is a specific member of an object or a class

  10. Object-Oriented analysis and design using UML • Attributes • If objects are similar to nouns, attributes are similar to adjectives that describe the characteristics of an object • Number of attributes depends on the business requirements of the information system and its users • Systems analysts define an object’s attributes during the system design process

  11. Object-Oriented analysis and design using UML • Methods • A method defines specific tasks that an object can perform • Just as objects are similar to nouns and attributes are similar to adjectives, methods resemble verbs that describe what and how an object does something

  12. Object-Oriented analysis and design using UML [1] The PARENT object includes five attributes and three methods. The CHILD object includes four attributes and five methods The DOG object includes six attributes and four methods.

  13. Object-Oriented analysis and design using UML • Messages • A message is a command that tells an object or class to perform a creation method • Polymorphism: The concept that a message gives different meanings to different objects depend on the methods

  14. Object-Oriented analysis and design using UML [1] The message ADD STUDENT signals the STUDENT class to perform the ADD STUDENT method the ADD STUDENT method requires the STUDENT object to perform nine specific steps.

  15. Object-Oriented analysis and design using UML [1] An example of polymorphism, the message GOOD NIGHT produces different results, depending on which object receives it.

  16. Object-Oriented analysis and design using UML • You can view an object as a black box, because a message to the object triggers changes within the object without specifying how the changes must be carried out. The black box concept is an example of encapsulation. • Encapsulation means that all data and methods are self-contained • By limiting access to internal processes, an object prevents its internal code from being altered by anther object or process • Encapsulation allows objects to be used as modular components anywhere in the system, because objects send and receive messages but do not alter the internal methods of other objects

  17. Object-Oriented analysis and design using UML • Classes • An object belongs to a group or category called a class that is optimal for reuse and maintainability • All objects within a class share common attributes and methods • Objects within a class can grouped into subclass , which are more specific categories within a class • A class can belong to a more general category called a superclass

  18. Object-Oriented analysis and design using UML [1] the PERSON superclass includes common attributes and methods. EMPLOYEE is a class within the PERSON superclass. INSTRUCTOR is a subclass within the EMPLOYEE class.

  19. Sequence Summary • The unified modeling language (UML) is a widely used method of visualizing and documenting an information system • UML is just a standard diagramming notation. It is just a tool, not a skill that is valuable in itself. • An object represents a real person, place, event, or transaction that are relevant to the system we are analyzing. • An object includes data and the processes that affect that data • Object oriented terms include classes, attributes, instance, messages, and methods • Classes include objects that have similar attributes, or characteristics • Individual members of a class are called object instances • Objects can send massages, or commands, that require other objects to perform certain methods • A method defines specific tasks that an object can perform

  20. Sequence Summary • In this Sequence we have • Defined and explained object oriented analysis • Defined and explained the unified modeling language (UML) • Defined and explained object oriented terms includes objects, classes, attributes, instance, messages, and methods

  21. Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt Publisher: SHELLY CASHMAN SEWIES. [2] system analysis and design, sixth edition Authors: Kenneth E. Kendall and Julie E. Kendall Publisher: Prentice Hall [3] Modern Systems Analysis and Design Third Edition Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich Publisher: prentice hall

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