lecture 1 software reliability

ICT 312Software Reliability & Quality

AssuranceLecture Notes

By: Anthony AngmorLecturer, Faculty of Informatics

Ghana Telecom University College

ICT 312: Software Reliability and Quality Assurance

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Ghana Telecom University CollegeTesano - Accra

Module:Software Reliability and Quality Assurance

Lecture 1: Introduction


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Module Aims / Objectives

Learning Outcome

Topics

Group Project Assignment

Introduction – SRE

Module Aims / Objectives

• Primarily this module aims at:– introducing students to the principles underlying

software reliability.

– introducing students to the processes that underlie the quality into software development and providing students with the basis for managing quality in software products.

– enabling students to plan and implement software quality assurance as a systematic pattern of actions in the software life cycle.


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Learning Outcome• On completion of this module, students should be

able to:– define Software Reliability and explain the importance of

the Software Reliability Measurements / Metric.

– Demonstrate understanding of the role of quality assurance in software projects.

– apply various metrics to measure the quality of software process and software products.

– develop quality plans, conduct quality audit and justify the need for quality assurance.


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TOPICSIntroduction

Overview of Computer SoftwareSoftware Reliability: Definition

Importance of Software ReliabilityReliability Models

Tools and Methods of ReliabilitySoftware Quality

Quality Management Activities Quality Assurance Systems and Standards

Quality Assurance ActivitiesSoftware Safety and Security


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GROUP PROJECT ASSIGNMENT• Identify any one Commercial-Of-The-Shelf (COTS)

software package of your choice OR Design your own small software and access its’ relative reliability using any three (3) standard reliability measurements/metrics.

• Suggest any five (5) ways in which the software package so referenced can be improved and made more reliable.

• Prepare a 10 minutes presentation on the identified software, including your findings to be delivered in class on Wednesday, 23 & 30 March, 2011 from 10:15am prompt.


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Ghana Telecom University CollegeTesano - Accra

Course:Software Reliability and Quality Assurance

Lecture 1


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Introduction

Overview of Computer Software

What is meant by “Software Reliability”?

Distinction between “a Failure” and “a Fault”

Approaches to Reliability:Developer – Oriented

User – Oriented

Introduction

• Computers and their software plays vital role in our lives in this computer age.

– e.g. TV’s, telephones etc. are having their analog and mechanical parts replaced by digitized CPUs and software.

– the computer industry is booming exponentially with a continuously lowering cost and improved processors and software-controlled systems.


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Introduction (cont’d)

• Advanced technology has allowed software to permeate our lives, e.g.:– Comfortable and convenient lifestyle

– Increased use of computerized control systems in safety critical applications

• E.g. flight control, nuclear plant monitoring, robotic surgery, military applications, etc

• Software needs to be ‘‘sufficiently good’’ for its application


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Introduction (cont’d)

• Software is developed by humans:– Humans are not perfect– There is a need to strive for perfection

• Can we expect “perfect software” in practice?

• Consumers have high expectations for software:– Realized the power of software– A huge market has developed


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Essential Difficulties

• The goal of producing “perfect software” remains elusive [Brooks 86] due to:– Complexity:

• Functional complexity• Structural complexity• Code complexity, …

– Changing requirements

• Software faults introduced in all phases of the System Development Life-Cycle

R.A Brooks, A Robust Layered Control System for a Mobile Robot, IEEE Journal of Robotics and Automation, 2 (1), 1986 Slide 13

Overview of Computer Software


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ComputerSoftware

ApplicationSoftware

SystemSoftware

SystemManagement

Programs

SystemDevelopment

Programs

GeneralPurpose

ApplicationPrograms

Application-Specific

Programs

•Web Browsers

•Electronic Mail

•Word Processing

•Spreadsheets

•ERP

•Customer R/ship Management

•Transaction Processing

•Operating Systems

•DBMS

•Application Servers

•System Utilities

•CASE packages

•Programming Editors

•Programming Language Translators

Performs info processing tasks for end users

Manages & supports computer systems and networks

Characteristics of Comp Software

• It does not age, rust, wear-out, deform or crack.

• There are no environmental constraints for software to operate as long as the hardware processor it runs on can operate.

• It cannot be seen or touched, but it has a physical existence and is crucial to system functionality.


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Software Tragedies

• Some people think that once a software can run correctly, it will forever be correct, but tragedies and chaos caused by softwareproves this thinking to be wrong.

• Software can make decisions, but can just be as unreliable (i.e. imperfect) as human beings.


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lecture 1 software reliability

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