1. Introduction To System Analysis and Design

2. What Is An Information System?
An information system is a collection of interrelated components that collect, process, store, and provide as output the information needed to complete a business task.

3. Examples of Information Systems
Course registration system
Online order system
Online banking system

4. What Is System Analysis About?
Understanding the goals and strategies of the business.
Defining the information requirements that support those goals and strategies.
It is not about programming.

5. System Analysis vs. System Design
Investigation of the problem and requirement rather than solution.
System Design:
A conceptual solution that fulfills the requirements, rather than implementation.

6. System Analyst
A business professional who uses analysis and design techniques to solve business problems using information technology.

7. The Role of a System Analyst
Investigate, analyze, design, develop, install, evaluate, and maintain a company’s information systems.
Business knowledge.
Business problem solver.
Help translate business requirements into IT projects.

8. Traditional System Development Life Cycle (SDLC)

9. Traditional System Development life Cycle (SDLC)
Project planning – initiate, ensure feasibility, plan schedule, obtain approval for project
Analysis – understand business needs and processing requirements
Design – define solution system based on requirements and analysis decisions
Implementation – construct, test, train users, and install new system
Support – keep system running and improve it

10. Two Approaches to System Development
Traditional (Structured) approach
Also called structured system development
Structured analysis and design technique (SADT)
Includes information engineering (IE)
Object-oriented approach
Also called OOA, OOD, and OOP
Views information system as collection of interacting objects that work together to accomplish tasks

11. Structured System Development
Structure Programming
Top-down Programming
Structured Design
Structured Analysis

12. Object-Oriented Approach
Completely different approach to information systems
Views information system as collection of interacting objects that work together to accomplish tasks
Objects – things in computer system that can respond to messages
Conceptually, no processes, programs, data entities, or files are defined – just objects
OO languages: Java, C++, C# .NET, VB .NET

13. Object-oriented Analysis and design (OOAD)
OOAD essential for creating well-designed,
& maintainable software system
All Software Analysis and Design is preceded by the analysis of requirements.
Analysis models the “real-world” requirements, independent of the implementation environment.
Design applies object-oriented concepts to develop and communicate the architecture and details of how to meet requirements.

14. Unified Modeling Language (UML)
UML (Unified Modeling Language) is a graphical language that is suit-able to express software or system requirements, architecture, and design.
UML used for both database and software modeling
UML modeling also supports multiple views of the same system.
use case diagram shows the purposes of the system (use cases) and the users (actors).

15. UML diagrams Can be categorized as the fallowing: Structural diagrams:
to show the building blocks of your system—features that don’t change with time.
Ex: Class diagram
Behavioral diagrams:
to show how your system responds to requests or otherwise evolves over time.
Ex: Use case diagram
Interaction diagrams:
Is a type of behavioral diagram.
To depict the exchange of messages within a collaboration (a group of cooperating objects).
Ex: Sequence diagram & Collaboration diagram

16. UML Diagrams Another way of categorizing UML diagram: Static diagrams
to show the static features of the system. (no change)
Dynamic diagrams
to show how your system evolves over time.
Functional diagrams:
to show the details of behaviors and algorithms.

17. Object-oriented analysis (OOA)
Trying to figure out what the users and customers of a software effort want the System to do.
Builds a “real-world” model from requirements
client interviews, domain knowledge, real-world experience collected in use cases and other simple notations
OOA models address three aspects of the system (its objects)
class structure and relationships
sequencing of interactions and events
data transformations and computations

18. Models of Object-Oriented Analysis (UML)
Structural Model (Data-Oriented)
static features
what objects are in the system?
how are they related?
Dynamic Model (Action-Oriented)
behavioral aspects
what events occur in the system
when do they occur and in what order?
Functional Model (Both Data and Actions)
data transformations
“what” does the system do

19. Class Diagram Created During OO Analysis

20. Ex: Use Case (Analysis)
Start from requirements
Describe response of system to events
Normal flow of action
Error and exception handling
Can implement tests to check use cases

21. OOD: Object Oriented Design
Emphasizes a conceptual solution that fulfils the requirements specified in the analysis.
Need to define software objects and how they collaborate to fulfill the requirements.
For example, in the Library Information System, a Book object may have a title attribute and a display() method.
Designs are implemented in a programming language.
In the example, we will have a Book class in Java.

22. Objects
In an OO approach, a system consist of a collection of interacting objects.
An object is a computational entity which Provide services with which other entities may
interact
○Typically, the services consumer sends a message
( requesting the service) to the provides object
○Possesses
Sate
-Information that the object holds , called (attributes)
Behaviour
-Operation it can perform , called (method)

23. Messages
Interaction is achieved by one object sending a message to another
Message has
A sender
A receiver
Message contents :
A reference to an operation of the receiver
Possible additional information (parameters)
Some messages return information to the sender

24. Why Objects? Encapsulation Message-based Invocation Data Hiding
Helps to organize data & behavior into meaningful associations.
Message-based Invocation
Helps to make code adaptable and reusable
Data Hiding
Helps to manage complexity, since programmer can control the data that objects are allowed to do manipulate

25. Classes A Class Describes a set of equivalent objects
○Hence, operates like a data type of objects
○Typically, every object in a system belongs to a class
Provides a useful way of representing and implementing the shared state and behavior of the objects that it describes

26. Why Class Inheritance Polymorphism a form of reuse
means same operation may behave differently on different classes.

27. Inheritance Example