INTRODUCTION TO SYSTEM ANALYSIS AND DESIGN

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Information System2

What Is An Information System?

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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.

Examples of Information Systems

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Course registration system Online order system Online banking system

Why Are Information Systems Important?

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Support business functions in modern business organizations

Make business more competitive Enhance productivity and profits

Types of Information Systems

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Customer Relationship Management (CRM) Supply Chain Management (SCM) Accounting and Financial Management (AFM) Human Resource Management (HRM) Manufacturing Management Knowledge Management (KM) Collaboration Support Systems (CSS) Business Intelligence System

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Information Systems and Component Parts

System Analysis8

What Is System Analysis About?

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Understanding the goals and strategies of the business.

Defining the information requirements that support those goals and strategies.

It is not about programming.

System Analysis Vs. System Design

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Systems analysis is a process of understanding in detail what a system should accomplish.

Systems design is a process of specifying in detail how components of an information system should be physically implemented.

System Analyst11

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

The Role of a System Analyst Investigate, analyze, design, develop,

installs, evaluate, and maintains a company’s information systems.

A business problem solver The solution to the “problem” is

generally a new information system Help translate business requirements

into IT projects.

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Typical Problems System Analyst Typically Solve

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Customers want to order product anytime of the day.

Suppliers want to minimize inventory holding costs.

Marketing want to know customer needs better.

Management want to analyzing financial information more efficiently.

The Analyst as a Business Problem Solver

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Has computer technology knowledge and programming expertise

Understands business problems Uses logical methods for solving problems Has fundamental curiosity Wants to make things better Is more of a business problem solver than

a technical programmer

What is your problem solving approach?

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Assume that you are deciding whether to buy a new laptop to replace the old one.

Analyst’s Approach to Problem Solving

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1. Research and understand the problem

2. Verify benefits of solving problem outweigh the costs

3. Define the requirements for solving the problem

4. Develop a set of possible solutions (alternatives)

5. Decide which solution is best and recommend

6. Define the details of the chosen solution

7. Implement the solution

8. Monitor to ensure desired results

Required Skills of the Systems Analyst

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1. Technical2. Business3. People

1-Technical Knowledge and Skills

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Computers / peripheral devices (hardware)

Communication networks and connectivity Database and database management

systems (DBMS) Programming languages (for example,

VB.NET or Java) Operating systems and utilities

1-Technical Knowledge and Skills – Tools

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Software productivity packages Integrated development environments

(IDEs) for programming languages CASE tools, testing, documentation

support, reverse engineering, configuration management

1- Technical Knowledge and Skills – Techniques

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Project planning, systems analysis Systems design, database design,

network design Construction, implementation, systems

support

2- Business Knowledge and Skills

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Business functions performed by organization

Strategies, plans, traditions, and values of the organization

Organizational structure

Organization management techniques

Functional work processes

3- People Knowledge and Skills

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Systems analysts need to understand how people

Think

Learn

React to change

Communicate

Work (in a variety of jobs and levels)

3- People Knowledge and Skills (continued)

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Interpersonal and communication skills are crucial to

Obtaining information

Motivating people

Getting cooperation

Understanding the complexity and workings of an organization in order to provide necessary support

Hard and Soft Skills24

Hard skills are the skills in technical areas such as database design, programming, and telecommunication.

Soft skills are the skills in nontechnical areas such as interviewing, team management, and leadership.

Integrity and Ethics25

Analyst has access to confidential information, such as salary, an organization’s planned projects, security systems, and so on.

Must keep information private

Any impropriety can ruin an analyst’s career

Analyst plans security in systems to protect confidential information

Analyst-Related Careers26

ERP software related Business Analysts in different business

functions Auditing, compliance, and security Web Development

System Development27

The Systems Development Lifecycle

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SDLC provides overall framework for managing systems development process.

Two main approaches to SDLC Predictive approach – assumes project can be

planned out in advance Adaptive approach – more flexible, assumes

project cannot be planned out in advance All projects use some variation of SDLC

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Choosing the Predictive vs. Adaptive Approach to the SDLC

Traditional Predictive Approach to the SDLC

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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

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Information System Development Phases

SDLC and Problem Solving32

Organization recognizes problem (project planning)

Project team investigates, understands problem and solution requirements (analysis)

Solution is specified in detail (design) System that solves problem is built and

installed (implementation) System used, maintained, and enhanced to

continue to provide intended benefits (support)

Waterfall Model33

Waterfall model is an SDLC approach that assumes the various phases of a project can be completed sequentially – one phase leads into the next phase.

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“Waterfall” Approach to the SDLC

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Modified Waterfall Approachwith Overlapping Phases

Newer Adaptive Approaches to the SDLC

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Based on spiral model Project cycles through development activities over and

over until project is complete Prototype created by end of each cycle Focuses on mitigating risk

Iteration – Work activities are repeated

Each iteration refines previous result

Approach assumes no one gets it right the first time

There are a series of mini projects for each iteration

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The Spiral Life Cycle Model

Activities of Each SDLC Phase

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Predictive or adaptive approach use SDLC

Activities of each “phase” are similar Phases are not always sequential Phases can overlap

Activities of Planning Phase of SDLC

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Define business problem and scope

Produce detailed project schedule

Confirm project feasibility

Economic, organizational, technical, resource, and schedule

Staff the project (resource management)

Launch project official announcement

Activities of Analysis Phase of SDLC

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Gather information to learn problem domain

Define system requirements

Build prototypes for discovery of requirements

Prioritize requirements

Generate and evaluate alternatives

Review recommendations with management

Activities of Design Phase of SDLC

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Design and integrate the network

Design the application architecture

Design the user interfaces

Design the system interfaces

Design and integrate the database

Prototype for design details

Design and integrate system controls

Activities of Implementation Phase of SDLC

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Construct software components

Verify and test

Convert data

Train users and document the system

Install the system

Activities of Support Phase of SDLC

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Maintain system Small patches, repairs, and updates

Enhance system Small upgrades or enhancements to expand

system capabilities Larger enhancements may require separate

development project Support users

Help desk and/or support team

Approaches to System Development

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Two Approaches to System Development

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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

1- Traditional (Structured) approach

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Structured System Development

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Structure Programming Top-down Programming Structured Design Structured Analysis

Structured Programming48

Improves computer program quality Allows other programmers to easily read

and modify code Each program module has one beginning

and one ending Three programming constructs

(sequence, decision, repetition)

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Three Structured Programming Constructs

Top-Down Programming50

Divides complex programs into hierarchy of modules

The module at top controls execution by “calling” lower level modules

Modular programming

Similar to top-down programming

One program calls other programs to work together as single system

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Top-Down or Modular Programming

Structured Design52

What the set of programs should be What each program should accomplish How the programs should be organized

into a hierarchy

Main Principles of Structured Design

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Loosely coupled – module is independent of other modules

Highly cohesive – module has one clear task

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Structure Chart Created Using Structured Design Technique

Structured Analysis55

Define what system needs to do (processing requirements)

Define data system needs to store and use (data requirements)

Define inputs and outputs Define how functions work together to

accomplish tasks Data flow diagrams (DFD) and entity

relationship diagrams (ERD) show results of structured analysis

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Data Flow Diagram (DFD)

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Entity-Relationship Diagram (ERD)

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Framework of Structured Development

Information Engineering (IE)59

Refinement to structured development

Methodology with strategic planning, data modeling, automated tools focus

More rigorous and complete than SADT

Industry merged key concepts from structured development and information engineering approaches into traditional approach

2- Object Oriented Approach

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Object-Oriented Approach61

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

Object-oriented Analysis anddesign (OOAD) OOAD essential for creating well-

designed, & maintainable software system using

All Software Analysis and Design is preceded by the analysis of requirements.

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Terminologies of O-O Approach

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Object-oriented analysis (OOA) Object-oriented design (OOD) Object-oriented programming (OOP)

OOA - OOD - OOPAnalysis

Design

Implementation

“Baseball Model”

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Object-oriented analysis (OOA)

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Defines types of objects users deal with Shows use cases are required to complete tasks How to get understanding of what we want to

build investigation of the problem (rather than how a solution is defined)

During OOD, there is an emphasis on finding and describing the objects (or concepts) in the problem domain.

For example, concepts in a Library Information System include: Book, and Catalog.

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Class Diagram Created During OO Analysis

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

Can be quite formal– UML diagrams

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Use Case Summary

Create use cases from requirements– Response of system to events– Normal and errors/exceptions

Leads to tests– Map use cases to tests

Use cases are not designs– That's how you manage to satisfy the

tests derived from use cases

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Object-oriented design (OOD)

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Defines object types needed to communicate with people and devices in system

Shows how objects interact to complete tasks

Refines each type of object for implementation with specific language of environment

UML is used in this phase

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.

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Analysis vs. Design

– Discovery - Invention– What? - How?– Physical - Logical

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Object-oriented programming (OOP)

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Writing statements in programming language to define what each type of object does

OO Programming Language (e.g. C++, Java,

smalltalk, …)

OOP: Object-Oriented Programming

• During Implementation, or Object-Oriented Programming, design objects are implemented, such as a book class in Java.

• Implementation is also known as Coding or Construction.

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Objects

concepts, concrete or abstract, with meaning derived from the problem domain “the real world”

provide a basis for implementation encapsulation of state (data values) and

behavior (operations)

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Objects (cont.)

Exhibit behavior by invoking a method in response to a message

instances of classes an object-oriented program is a

collection of autonomous interacting and collaborating objects

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Classes objects sharing common

characteristics dictate the behavior of the object contain

state: attributes, fields, variables, data member

behavior: functions, methods, function member

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3 Pillars of Object-Orientation encapsulation

inheritance

polymorphism

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Encapsulation

combination of state and behavior implementation details are hidden

internally internal mechanisms can change while

public interfaces remain stable state may be retrieved using public

methods behavior consists of methods activated

by receipt of messages

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Inheritance organization of classes into a hierarchical

inheritance tree data and behavior associated with

classes higher in the tree are accessible to those classes lower in the tree

terminology ancestor/descendant superclass/subclass generalization/specialization

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Another Inheritance Diagram

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Polymorphism

polymorphism: many forms localizes responsibility for behavior object automatically uses correct

implementation for a method many objects can respond to the same

message minimizes interface parameter passing

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Polymorphism

treat many types (all derived from the same type) as if they were all one type

single piece of interface works on all these types

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Polymorphism Example83