4. Information System Development

7/30/2019 4. Information System Development

1/31

1

TOPIC 4INFORMATION SYSTEM

DEVELOPMENT


2/31

2

1.0INTRODUCTION

As in life, information system grows old and passes on. There are needs for newrequirements in an existing information system as company/ organization objectives

change. These requirements are the reasons why the company/ organization need to

create a new information system or to modify an existing information system.

What initiates the system development life cycle?i. The reasons to create or modify an information system such as:

To correct problem in an existing system. To improve an existing system. Outside group may mandate change. Competition can lead to change.

ii. A request for system services: Formal request for new or modified information system (Also called

project request)

The life cycle for improving the quality of information is called system development lifecycle.

1.1PEOPLE WHO PARTICIPATE IN THE INFORMATION SYSTEM

DEVELOPMENT


3/31

3

People who participates in the information system development are:PEOPLE DESCRIPTION

Team Leader/

Project Leader

- One member of the team whomanages and controls project budget and schedule

- Identifies elements for project:o Goal, objectives, and expectations, collectively called

scope

o Required activitieso Time estimates for each activityo Cost estimates for each activityo Order of activities


4/31

4

PEOPLE DESCRIPTION

o Activities that can take place at same timeSystem Analyst - Responsible for designing and developing information system

- Liaison between users and IT professionalsProgrammers - Converts the system design into a working system using

appropriate programming language such as C++, Java, Visual

Basic, and so on.

Users - Anyone for whom system is being built*Note: please refer to the given picture for detail information.

What is the project team?i. Formed to work on project from beginning to end

ii. Consists of users, systems analyst, and other IT professionals What is project management?

i. Process of planning, scheduling, and controlling activities during systemdevelopment cycle

ii. Project leader identifies elements for project What is a Gantt chart?

i. Popular tool used to plan and schedule large, complex projects


5/31

5

What is project management software?i. Program used by project leaders to plan, schedule, and control development

projects e.g. Microsoft Project.

Knowing the stages of the system life cycle and related software options will help user tomake better decisions regarding the development of information systems.


6/31

6

The four stages of this life cycle are:a. Birth stage

o In the birth stage of the system life cycle, someone has an idea abouthow the computer can help provide better and timelier information.

b. Development stage

o The idea becomes a reality during development stage of the system lifecycle. In this stage, IT professionals and users work together to analyze an

organizations information processing needs and design an information system.

o Then, the design specifications are translated into programs and thesystem is implemented.

c. Production stages

o Upon implementation, the information system enters the productionstage and becomes operational, serving the information needs of an organization.

o This stage normally will last from four to seven years. During this stage,an information system is continuously modified to keep up with the changing

needs of the organization.

d. End-of-life stage

o The accumulation of system modifications to a dynamic informationsystem eventually takes its toll on system efficiency.

o The end-of-life stage arrives when an information system becomes socumbersome to maintain that it is no longer economically or operationally

effective.

o At this time, it is discarded and the system life cycle is repeated.


7/31

7

2.0APPROACHES FOR SYSTEM DEVELOPMENT

2.1 SYSTEM DEVELOPMENT LIFE CYCLE (SDLC)

Figure 2(a): Phases of SDLC

2.1.1 SDLS PHASES

There are 5 phases of SDLC, or known as Waterfall Model:

PHASE 1: SYSTEM PLANNING

Begins when steering committee receives project request Steering committeedecision-making body for the company Function of committee:

Review and approve project requests Prioritize project requests Allocate resources Form project development team for each approved project

The purpose of system planning is to identify the nature scope of the businessopportunity or problem.

Recognize problems of existing system and recommends that a new system bedeveloped.

System request begins the process & describes problems or desired changes.

System

PlanningSystem

AnalysisSystem

DesignSystem

ImplementationSystem

Operation &

Support

PreliminaryInvestigation

Report SystemRequirements

Document SystemDesign

SpecificationCompleteFunctioning

InformationS stem

OperationalInformation

System


8/31

8

System planning includes preliminary investigation whose key part is a feasibilitystudy

PHASE 2: SYSTEM ANALYSIS

Conduct preliminary investigation, also called feasibility study What is the preliminary investigation?

- Determine exact nature of problem or improvement and whether it is worthpursuing

Findings are presented in feasibility report, also known as a feasibilitystudy

Perform detailed analysis: current system analysis and user requirement analysis. What is detailed analysis (Sometimes called logical design)?

1. Study how current system works2. Determine users wants, needs, and requirements3. Recommend solution

Conceptual design.- Purpose is to build a logical model of the new system- First step is requirements modeling where you investigate business processes and

document what the new system must do.

There are two type of system model: process modeling and object modeling. What is process modeling?

- Technique that describes processes that transform inputs into outputs- Also called structured analysis and design- Three tools used for process modeling

Entity-relationship diagrams Data flow diagrams Project dictionary

Contains all the documentation and deliverables of project Helps keep track of huge amount of details in system Variety of techniques to enter items in project dictionary

(Structured English, Decision tables, Decision trees, Data

dictionary)


9/31

9

What is Structured English? Used to explain details of process

Figure 2(b): Structured English

What is a decision table? Lists variety of conditions and actions that correspond to each

condition

Figure 2(c): Decision Table

What is a decision tree? Shows conditions and actions graphically


10/31

10

Figure 2(d): Decision Tree

What is a data dictionary? Stores name, description, and other details about each data item

Figure 2(e): Data dictionary

What is object modeling?- Combines data with the processes that act on data into single unit called an object

(Objectan item that can contain both data and procedures that read or

manipulate the data)

- Sometimes called object-oriented (OO) analysis and design- Uses Unified Modeling Language (UML)graphical tool for documenting

system

Alternative identification and evaluation (Hardware and Software Alternatives) End product is the System requirements document


11/31

11

PHASE 3: SYSTEM DESIGN

Purpose is to create a blueprint that will satisfy all documented requirement Identify all outputs, inputs and processes Avoid misunderstanding through manager and user involvement End product is system design specification

- Input and output design- File or database design- Program design- Procedure design

PHASE 4: SYSTEMS IMPLEMENTATION

New system is constructed. Specifications of design details:- Layout of all screens, reports and forms- Organization of all records, files and database.- Descriptions of all programs.- Descriptions of all manual procedures.- Specification for all hardware.- Description of all personnel.

Acquire the 5 components of the new system (hardware, software, stored data,personnel and procedures).

Write, test (system test) & document programs What are the four types of tests performed by system developers?

- Unit Test - Verifies each individual program works by itself- Systems test - Verifies all programs in application work together- Integration Test - Verifies application works with other applications- Acceptance Test - Verifies the new system works with actual data

File conversion and system installation occurs What are conversion strategies?

- Used to change from old system to new system


12/31

12

Figure 2(f): Conversion Types

Users, managers, IT staff trained to operate and support the system What is training?

- Showing users exactly how they will use new hardware and software in system

Figure 2(g): Training session

System evaluation performed


13/31

13

PHASE 5: SYSTEMS OPERATION AND SUPPORT

New system supports operations Maintenance changes correct errors or meet requirements Enhancements increase system capability After several years of operation, systems need extensive changes. SDLC ends with system replacement

2.1.2 USER INVOLVEMENT IN EACH SDLC PHASES

System development steps User involvement

System Planning

Problem recognition and definition High

Feasibility analysis Low

System Analysis

Current system analysis High

User requirement analysis Very high

Conceptual design Low

Alternative identification and evaluation Low

System design

Input and output design High

File or database design None

Program design None

Procedure design High

System implementation

System acquisition Low

System testing Moderate

System installation Very high

System maintenance Varies

Table 2(a): User involvement in each SDLC phases


14/31

14

2.1.3 OVERVIEW OF FEASIBILITY

What is feasibility?- Involved in System Planning phase.- Measure of how suitable system development will be to the company- Feasibility study is a series of test to see whether it is worthwhile to proceed

further (whether it is feasible to develop the system).

- It is a vital part of every systems project.

A feasibility study includes four feasibility tests:- Technical feasibility- Operational feasibility- Economic feasibility (also called cost/benefit feasibility)- Schedule feasibility

a. Technical Feasibility

-Determine whether the system can be developed using existing technology.-The technical resources needed to be developed, purchase, install or operate

the system.

-Examples of Important Questions/ Tasks: Does the company have the necessary hardware, software and network

resources? If not, can those resources be acquired without difficulties?

Will the hardware and software environment be reliable? Will itintegrate with other company information system, both now and

future?

Does the proposed platform have sufficient capacity for future needs?If not, can it be expended?

b. Operational Feasibility

- Decide whether the people in the organization will use the system.

- The system will used effectively after it has been developed

- No difficulties with the new system, it will produce expected benefits

-Examples of Important Questions/ Tasks: Does management support the project?


15/31

15

Do users support the project? Is the current system well liked and effectively used? Do users need for change? Will the new system result in a workforce reduction? Will the new system place any new demands on user or require any

operating changes?

c. Economic Feasibility

-Evaluate the costs and benefits of the system and determine whether thetotal benefits are greater than the total costs over the life of the system.

-The projected benefits of the proposed system outweigh the estimated costsusually considered the total cost of ownership (TCO), which includes

ongoing support & maintenance costs, as well as acquisition costs

-To determine TCO, cost estimation on:i. People, including IT staff and usersii.Hardware & equipmentiii.Software, including in-house development as well as purchases from

Vendors

iv.Formal & informal trainingv.Licenses & feesvi.Consulting costsvii. The estimated cost of not developing the system or postponing

the Project.

-To evaluate the economic feasibility of the system, the expected cost ofdeveloping and operating the system are compared with the expected

benefit, in a process called cost/ benefit analysis:

i. Tangible benefits:

Benefits that can be measured in dollars (decrease of expenses,increase in revenue)

Scheduling system that reduces overtime Online tracking system that improves service & decrease need for

clerical staff.

Cuts excess inventory & eliminates delays.


16/31

16

ii. Intangible benefits:

Benefits that cannot be measured in dollars User-friendly, improve user satisfaction Better information for making decision Enhance companys image. Raising employee morale Improve customer service

d. Schedule Feasibility

- The project can be implemented in an acceptable timeframe.- System Analyst must consider the interaction between time and costs- Examples of Important Questions/ Tasks:

i. Can the company or IT team control the factors that affectschedule feasibility?

ii. Has management established a firm timetable for the project?

2.2 PROTOTYPING

The CASE tool kit enables the system development project team to work with users todevelop a prototype system, a model of a full-scale system.

Prototype of a system is a partial version of the system that acts like the real system butdoes not perform all the required function of the system.

A prototype system permits users a sneak preview of the completed system. A typicalprototype system:

a. Handles the main transaction-oriented proceduresb. Produces common reportsc. Permits typical interactions (data entry and inquiries) to the database

User becomes an integral part of an interactive computer-assisted process that results inan information system.

The three objectives of prototyping are:a. To analyze the current situation

b. To identify information needs

c. To develop a model of the proposed system, often called the target system


17/31

17

The CASE tool kit enables the system development project team to work with users todevelop a prototype system, a model of a full-scale system.

The prototyping process:a.Phase I Define system specificationsb.Phase II Create prototyping systemc.Phase III Refine prototyping systemd.Phase IV Develop operational system

Prototype includes sample screens and reports. It can be developed quickly using specialprototyping software.

User then has chance to change their requirements, and the system analyst modifies theprototype to reflect the changes.

After several such modifications, the prototype reaches a point at which the user issatisfied with it.

Prototyping replaces the user requirement analysis and conceptual design steps of thesystem analysis phase of the information system development process.

2.3 RAPID APPLICATION DEVELOPMENT (RAD)

Figure 2(h): RAD phases

RAD is a team-based technique that speeds up information system development andproduces a functioning system.

The development of the system is done in a short time. It requires significant user involvement in the development process. This approach uses some of the techniques already discussed:

a. Prototype: used to determine user requirementsb. CASE tools: used to speed up the analysis and design process

Requirements

Planning

User DesignConstruction

Cutover


18/31

18

There are 4 phases of RAD:

Phase 1: Requirements Planning

High-level managers, executives, and knowledgeable end users determine systemrequirements.

Outcome:- An outline system area model (entity and process models)

- A definition of the system's scope.

Phase 2: User Design

End users and Information System professionals participate in JAD workshop, to developprototype of system design by using CASE tools.

Outcome:- Diagrams defining the interactions between processes and data

- Preliminary layouts of screen

- Prototypes of critical procedures

Phase 3: Construction

A small team of developers, working directly with users, finalizes the design and buildthe system by using the CASE tools code generator.

Outcome: Product

Phase 4: Cutover

Implementing the new system and managing the change from the old system environmentto the new one.

2.4 OBJECT-ORIENTED ANALYSIS (OOA)

O-O analysis combines data & processes into objects Data and instructions for processing the data are combined to form an object. Object oriented analysis and design involves analyzing the objects that are important in

the system and designing the system based on these objects.

Object is a member of a class Class is a collection of similar objects


19/31

19

Objects possess properties Methods change an objects properties The system is usually implemented by using an object-oriented programming language. Object-oriented analysis and design replaces much of the system development process. System planning, current system analysis and user requirements analysis are still needed. It replaces the remainder of the system analysis phase and the system design phase.

Objects

Class Name

2.5 SPIRAL

The spiral model focuses on reducing risk. It blends the best features of the waterfall and other models. It defines four major activities:

Phase 1: Objective settingDetermine objectives, alternatives, and constraints.

Phase 2: Risk analysisIdentify risks and develop plans to reduce them.

Phase 3: Development and validation Phase 4: Plan next cycle

Figure 2(i): Object-Oriented approach example for System development method


20/31

20

Figure 2(j): Phases of Spiral Model

2.6 EXTREME PROGRAMMING (XP)

Perhaps the best-known and most widely used agile method. Extreme Programming (XP) takes an extreme approach to iterative development.

- New versions may be built several times per day;- Increments are delivered to customers every 2 weeks;- All tests must be run for every build and the build is only accepted if tests run

successfully.

In XP, user requirements are expressed as scenarios or user stories. These are written on cards and the development team break them down into

implementation tasks. These tasks are the basis of schedule and cost estimates.

The customer chooses the stories for inclusion in the next release based on their prioritiesand the schedule estimates.


21/31

21

Figure 2(j): The XP release cycle


22/31


23/31

23

Symbols Name Function

Process Any steps that involves

manipulating data

External entity A person, organization or another

system that sends input (data

source) or receives output data (data

destination).

Data store A collection of data kept by the

system in any form, such as in a file

or database.

Data flow Direction of the data flow

Table 2(b): Symbols used in DFD

Table 2(k): An example of a DFD for Vendor Web System


24/31

24

3.2 Entity-Relations Diagrams (ERD)

System Analyst uses ERD to show the design of a database; it is basically about therelationship between entities in a database.

An entity is something about which data is stored in a database, such as a customer, anitem in inventory, or an order.

A relationship is an association between entities. Below are the symbols used in ERD:

Symbol Name

Entity

1 1 One-to-one relationship

1 N One-to-many relationship

M N Many-to-many relationship

Table 2(c): Symbols used in ERD


25/31

25

Table 2(l): An example of a ERD for Vendor Web System

Other system development tools for Object Modeling include Use Case Diagram andClass Diagram.

What is a use case diagram?o Graphically shows how actors interact with information system

Actoruser or other entity Use casefunction that actor can perform

Figure 2(m): Use Case diagram


26/31

26

What is a class diagram?o Graphically shows classes and subclasses in system

Class is group of objectsCan have lower levels called subclasses

Figure 2(n): Class Diagram

3.3 COMPUTER-AIDED SOFTWARE ENGINEERING (CASE) TOOLS

Computer-aided software engineering (CASE) is the scientific application of a set oftools and methods to a software system which is meant to result in high-quality, defect-

free, and maintainable software products.

It also refers to methods for the development of information systems together withautomated tools that can be used in the software development process.

There are 3 categories of CASE tools:Category Tools

Workbenches

Environment

Definition CASE tools are a class

of software that

automates many of the

activities involved in

various life

cycle phases.

Workbenches integrate

several CASE tools into

one application to support

specific software-process

activities.

An environment is a

collection of CASE

tools and workbenches

that supports the

software process.


27/31

27

Functions a. To develop graphic

models of application

screens to assist end

users to visualize how

an application will

look after

development.

b. To transform the

prototyped functional

requirements into

detailed design

documents.

c. Programmers can

then use automated

code generators to

convert the design

documents into code.

CASE workbenches can

be further classified into

following 8 classes:

1. Business planningand modeling

2. Analysis anddesign

3. User-interfacedevelopment

4. Programming5. Verification and

validation

6. Maintenance andreverse

engineering

7. Configurationmanagement

8. Projectmanagement

CASE environments

are classified based on

the focus/basis of

integration

1. Toolkits2. Language-

centered

3. Integrated4. Fourth

generation

5. Process-centered

What is documentation?i. Collection and summarization of data and information

ii. Includes reports, diagrams, programs, and other deliverables (Project notebookcontains all documentation for single project)


28/31

28

What are six data and information gathering techniques?


29/31


30/31

30


31/31

4. Information System Development

Documents

Transcript of 4. Information System Development