Session 1 Introduction to OOAD and UML Objectives

Session 1 Introduction to OOAD and UML

Objectives n n n Discuss the basic concepts of OOA and UML Discuss the concept and use of UML Give a whole preview of the elements of UML, and use simple examples to explain the function of UML OOAD with UML / Session 1 / 2 of 27

Object Oriented Analysis and Design (OOA&D) n n Object oriented Analysis and Design refers to the analysis and design of a system based on the concepts of object orientation. UML is a diagrammatic approach to model the software to be developed. OOAD with UML / Session 1 / 3 of 27

SDLC n n Software Development Life Cycle (SDLC) is a sequence of activities carried out by analyst, designers, and users to develop and implement an information system. Analyst – Studies requirements Designer – Designs the system User – An entity OOAD with UML / Session 1 / 4 of 27

Object Oriented Analysis (OOA) n n n Phase of the project during which a precise and concise model of the problem in terms of real world objects and concepts as understood by the user is developed. The analysis must also identify the relevant characteristics, interactions and relations between the entities. This kind of real life mapping to computer analysis is the advantage offered by the Object Oriented Analysis. OOAD with UML / Session 1 / 5 of 27

Object Oriented Design (OOD) n n n Programs are organized as co-operative collections of objects. The purpose of Object Oriented Design is to adapt the results of OOA phase. Designer defines the responsibilities, operations attributes and relationships of one or several classes. Designer also designs the database and applies normalization techniques. Diagrams can be classified into static or dynamic. OOAD with UML / Session 1 / 6 of 27

Advantages of OOA&D over Traditional Analysis and Design n n n Close match between what is being implemented and the actual problem. Promotes reuse of objects Since reuse of objects is possible, it reduces errors and maintenance problems. Reuse of objects also speeds up the process of design and development. Appeals to the working of human cognition, as it is our natural way of thinking. Propagates data encapsulation Helps to handle the complexity of software development and aids generation of adaptable and resilient software systems. OOAD with UML / Session 1 / 7 of 27

Modeling n n n n A model is a simplification of reality Provides the blueprints of a system Models may encompass detailed plans A good model includes those elements that have broad abstraction. Helps to visualize a system as it is or according to the need. Models permit to specify the structure or behavior of a system. Models give a template that guides in constructing a system. Models document the decisions that have been made OOAD with UML / Session 1 / 8 of 27

SDLC Phases-1 OOAD with UML / Session 1 / 9 of 27

SDLC Phases-2 n Preliminary Investigation (Feasibility Study) n An important outcome of the preliminary investigation is determining whether the system to be developed is feasible or not. n Requirement Analysis (Analysis) n Involves study of the current business system in detail and to find out how it works and where the improvements have to be made. OOAD with UML / Session 1 / 10 of 27

SDLC Phases-4 n Design of the System n n The design phase states how a system will meet the requirements identified during the systems analysis phase as mentioned in the Requirements Specifications. Identification of data entry forms, data elements, reports, outputs the new system should produce, data elements and tables for database. Sketch the form or display as expected to appear at the end of completion of the system. Computation procedures explaining the process of deriving the output from given input. OOAD with UML / Session 1 / 11 of 27

SDLC Phases-6 § Software Construction n n Actual construction (coding) of the programs System Testing n n n Actual software code construction Unit Testing: White Box testing Independent Unit Testing OOAD with UML / Session 1 / 12 of 27

SDLC Phases-8 n System Testing n n n After the programs are tested individually, the system as a whole needs to be tested. All the software modules are integrated and tested to ensure that they do not fail i. e. it will run according to specifications as mentioned in requirement specification document and in the way the users expected it to. Special test data is prepared as input for processing and the results are examined to find out any deviations from the desired results. OOAD with UML / Session 1 / 13 of 27

SDLC Phases-9 n System Implementation n n Developed system is deployed at the user’s site for use User personnel are trained The data files needed by the system are constructed System Maintenance n n Due to environmental changes, the software may turn obsolete and it may call for modifications and enhancements for its effective use. The activity of system maintenance may vary depending on the scale of modifications and enhancements. OOAD with UML / Session 1 / 14 of 27

Model The language used to represent a model is called a Modeling Language. Object Model can be explained as a model to represent objects of a system. n n Principle of Model Creation n The choice of what models to create has a profound influence on how a problem is attacked and how a solution is shaped. No single model is sufficient. Every nontrivial system is best approached through a small set of nearly independent models. OOAD with UML / Session 1 / 15 of 27

Object Oriented Model Creation n The contemporary view of software development is an object-oriented perspective. In this approach the main building block of all software systems is the object or class. OOAD with UML / Session 1 / 16 of 27

UML in Brief n n n n Use-Case diagrams to illustrate user interactions with the system. Class diagrams to illustrate logical structure Object diagrams to illustrate objects and links State diagrams to illustrate behavior Component diagrams to illustrate physical structure of the software. Deployment diagrams to show the mapping of software to hardware configuration Interaction diagram (i. e. , collaboration and sequence diagrams) to illustrate behavior. Activity diagrams to illustrate the flow of events in a Use. Case. OOAD with UML / Session 1 / 17 of 27

Introduction to UML n n n Some of the leading companies that have contributed towards and promoted the development of UML are Hewlett – Packard Microsoft Oracle IBM Unisys OOAD with UML / Session 1 / 18 of 27

History of UML OOAD with UML / Session 1 / 19 of 27

Application in different systems OOAD with UML / Session 1 / 20 of 27

Application in Software Development Life Cycle n n n Preliminary Investigation: Use Cases to capture the requirements of a customer. Analysis: Class diagrams are made at real world abstract level to depict their existence and relationship. Design: Classes are modeled Development: Programmers refer to the various UML diagrams prepared in the design stage to understand develop code. Testing: UML has different diagrams to support testing of software. OOAD with UML / Session 1 / 21 of 27

UML Overview n n Views- would mean ‘to observe’ or ‘to examine’ Diagrams- is a part of a specific view and when it is drawn it is allocated to a view. Relationships-provide a pathway for communication between objects. Modeling Elements-consist of symbols that help in preparing diagrams and views. OOAD with UML / Session 1 / 22 of 27

Model Elements Use case name Component Name Class Attributes Operations Dependency Generalization Association Aggregation (a form of Association) OOAD with UML / Session 1 / 23 of 27

“ 4+1” view OOAD with UML / Session 1 / 24 of 27

UML Hello World OOAD with UML / Session 1 / 25 of 27

Component n n Source code components (e. g. , . h, . cpp files, shell scripts, data files) Binary code components. Examples include: java Beans, Active. X controls, COM objects (DLL’s and OCX’s from VB), CORBA objects) Executable components (. exe’s) Stereotypes (with alternatives icons) may be used to define these specific kinds of components. OOAD with UML / Session 1 / 26 of 27

Summary n n n UML is a modeling tool Various Diagrams of UML are used to model a system UML is used many areas of applications UML is used in all the phases of SDLC The “ 4+1 view” architectural model is a simplified description (an abstraction) of a system from a particular perspective or vantage point, covering particular concerns, and omitting entities that are not relevant to this perspective. Different parts of UML are § § Views Diagrams Relationships Model Elements OOAD with UML / Session 1 / 27 of 27