Object Oriented System Analysis and Design (OOSAD)

1 OOSAD Module Page 1 Ambo University, Woliso Campus School of Technology and Informatics Department of Information Systems Object Oriented System Analysis and Design (OOSAD) COMPILED BY: HABTAMU KENO DEPARTMENT OF INFORMATION SYSTEMS 3, June, 2O WOLISO, ETHIOPIA OOSAD Module Page 2 Contents Chapter 1: Understanding the Basics: Object Oriented concepts .. 4 A Brief History .. 4 Object - Oriented Analysis .. 4 Object - Oriented Design .. 4 INTRODUCTION .. 5 THE Object MODEL .. 5 Programming .. 5 Benefits of Object Model .. 10 3. Object - Oriented System .. 10 Object - Oriented PRINCIPLES .. 11 Analysis .. 13 Chapter Two: Object Orientation the new software paradigm .. 19 2. Structured vs. Object Orientation paradigm .. 19 The Potential Benefits of the Object Oriented paradigm .. 19 The Potential Drawbacks of OO .. 20 Object Standards .. 21 Chapter 3: Gathering user requirements .. 22 3. An Overview of Requirements Elicitation.

2 22 Requirements elicitation includes the following activities: .. 22 Requirements Elicitation Concepts In this section, we describe the main requirements elicitation concepts used in this chapter. In particular, we describe .. 23 Functional Requirements .. 23 Nonfunctional Requirements .. 24 Fundamental requirements gathering techniques .. 25 Chapter 4: Ensuring Your Requirements are Correct: Requirement validation Techniques .. 26 4. Requirements Validation .. 26 The 6 Principles of Validation .. 26 Validation Techniques .. 27 Chapter 5: Determining What to Build: OO Analysis .. 29 Overview of Analysis artefacts and their Relationships .. 29 The Unified Modeling Language (UML) .. 31 UML BASIC NOTATIONS .. 33 UML STRUCTURED DIAGRAMS .. 35 UML BEHAVIORAL DIAGRAMS .. 38 Chapter 6: Determining How to Build Your System : OO Design .. 42 System Design .. 42 Object - Oriented Decomposition .. 42 OOSAD Module Page 3 Identifying Concurrency .. 42 Identifying Patterns.

3 43 Controlling Events .. 43 Handling Boundary Conditions .. 43 Object Design .. 43 Object Identification .. 44 Object Representation .. 44 Classification of Operations .. 44 Algorithm Design .. 44 Packaging Classes .. 45 Design Optimization .. 46 IMPLEMENTATION STRATEGIES .. 47 Chapter seven : Software Testing .. 51 TESTING AND QUALITY ASSURANCE .. 51 Testing Object - Oriented Systems .. 51 Unit Testing .. 51 Subsystem Testing .. 51 Testing .. 51 Categories of System Testing .. 51 Object - Oriented Testing Techniques .. 51 Techniques for Subsystem Testing .. 52 The Full-Lifecycle Object - Oriented Testing (FLOOT) .. 52 Quality Assurance .. 53 Quality Assurance .. 54 Quality Factors .. 54 Chapter 8: Software Process .. 55 Process .. 55 Software Process .. 55 8. 3. Processes and Process Models .. 55 Component Software Processes .. 56 Approach for Process Specification .. 57 of Software Process .. 57 Software Development Process Models.

4 59 Advantages of Prototyping .. 61 Limitations of Prototyping .. 61 Project Management Process .. 63 Process Management .. 66 The Unified Process .. 67 OOSAD Module Page 4 Chapter 1: Understanding the Basics: Object Oriented concepts A Brief History The Object - Oriented paradigm took its shape from the initial concept of a new programming approach, while the interest in Design and Analysis methods came much later. The first Object Oriented language was Simula (Simulation of real systems) that was developed in 1960 by researchers at the Norwegian Computing Center. In 1970, Alan Kay and his research group at Xerox PARK created a personal computer named Dynabook and the first pure Object - Oriented programming language (OOPL)-Smalltalk, for programming the Dynabook. In the 1980s, Grady Booch published a paper titled Object Oriented Design that mainly presented a Design for the programming language, Ada. In the ensuing editions, he extended his ideas to a complete Object Oriented Design method.

5 In the 1990s, Coad incorporated behavioral ideas to Object - Oriented methods. The other significant innovations were Object Modelling Techniques (OMT) by James Rumbaugh and Object - Oriented Software Engineering (OOSE) by Ivar Jacobson. Object - Oriented Analysis Object Oriented Analysis (OOA) is the procedure of identifying software engineering requirements and developing software specifications in terms of a software System s Object model, which comprises of interacting objects. The main difference between Object - Oriented Analysis and other forms of Analysis is that in Object - Oriented approach, requirements are organized around objects, which integrate both data and functions. They are modelled after real-world objects that the System interacts with. In traditional Analysis methodologies, the two aspects - functions and data - are considered separately. Grady Booch has defined OOA as, Object - Oriented Analysis is a method of Analysis that examines requirements from the perspective of the classes and objects found in the vocabulary of the problem domain.

6 The primary tasks in Object - Oriented Analysis (OOA) are: Identifying objects Organizing the objects by creating Object model diagram Defining the internals of the objects, or Object attributes Defining the behavior of the objects, , Object actions Describing how the objects interact The common models used in OOA are use cases and Object models. Object - Oriented Design Object Oriented Design (OOD) involves implementation of the conceptual model produced during Object - Oriented Analysis . In OOD, concepts in the Analysis model,which are technology independent,are mapped onto implementing classes, constraints are identified and OOSAD Module Page 5 interfaces are designed, resulting in a model for the solution domain, , a detailed description of how the System is to be built on concrete technologies. The implementation details generally include: Restructuring the class data (if necessary), Implementation of methods, , internal data structures and algorithms, Implementation of control, and Implementation of associations.

7 Grady Booch has defined Object - Oriented Design as a method of Design encompassing the process of Object - Oriented decomposition and a notation for depicting both logical and physical as well as static and dynamic models of the System under Design . Introduction Object - Oriented Analysis and Design (OOAD) is a software engineering approach that models a System as a group of interacting objects. Each Object represents some entity of interest in the System being modeled, and is characterised by its class, its state (data elements), and its behavior. Various models can be created to show the static structure, dynamic behavior, and run-time deployment of these collaborating objects. There are a number of different notations for representing these models, one such model is Unified Modeling Language (UML). THE Object MODEL Object Oriented development offers a different model from the traditional software development approach, which is based on functions and procedures. An Object - Oriented environment, software is a collection of discrete objects that encapsulate their data and the functionality to model real world Objects.

8 Object are defined, it will perform their desired functions and seal them off in our mind like black boxes. The Object - Oriented life cycle encourages a view of the world as a System of cooperative and collaborating agents. An objective orientation producers System that are easier evolve, move flexible more robust, and more reusable than a top-down structure approach. An Object orientation allows working at a higher level of abstraction. It provides a seamless transition among different phases of software development. It encourages good development practices. It promotes reusability. The unified Approach (UA) is the methodology for software development proposed and used and the following concepts consist of Unified Approach Programming Object - Oriented programming (OOP) is a programming paradigm based upon objects (having both data and methods) that aims to incorporate the advantages of modularity and reusability. Objects, which are usually instances of classes, are used to interact with one another to Design applications and computer programs.

9 The important features of Object Oriented programming are: Bottom up approach in program Design Programs organized around objects, grouped in classes OOSAD Module Page 6 Focus on data with methods to operate upon Object s data Interaction between objects through functions Reusability of Design through creation of new classes by adding features to existing classes Some examples of Object - Oriented programming languages are C++, Java, Smalltalk, Delphi, C#, Perl, Python, Ruby, and PHP. Grady Booch has defined Object Oriented programming as a method of implementation in which programs are organized as cooperative collections of objects, each of which represents an instance of some class, and whose classes are all members of a hierarchy of classes united via inheritance relationships . Object MODEL The Object model visualizes the elements in a software application in terms of objects. In this chapter, we will look into the basic concepts and terminologies of Object Oriented systems.

10 Objects and Classes The concepts of objects and classes are intrinsically linked with each other and form the foundation of Object Oriented paradigm. Object An Object is a real-world element in an Object Oriented environment that may have a physical or a conceptual existence. Each Object has: Identity that distinguishes it from other objects in the System . State that determines the characteristic properties of an Object as well as the values of the properties that the Object holds. Behavior that represents externally visible activities performed by an Object in terms of changes in its state. Objects can be modeled according to the needs of the application. An Object may have a physical existence, like a customer, a car, etc.; or an intangible conceptual existence, like a project, a process, etc. Class A class represents a collection of objects having same characteristic properties that exhibit common behavior. It gives the blueprint or description of the objects that can be created from it.