Software Reliability Engineering Process

Dr. Himanshu HoraSRMS College of Engineering & Technology

Bareilly (INDIA)

Software Reliability

IEEE 982.1-1988 defines software reliability as

“The ability of a system or component to perform its required functions under stated conditions for a

specified period of time.”

Is the probability that a system will operate without failure under given environmental conditions for a specified period of time.

Aims at fault-free performance of software systems

Software reliability engineering Engineering (applied science) discipline

Measure, predict, manage reliability

Statistical modeling

Customer perspective:• failures vs. faults• meaningful time vs. development days• customer operational profile

SRE Process

1.List Associated Systems

Lists all systems associated with the product that must be tested independently and are of two types - Base product & variations and Super-systems

2.Develop Operational Profiles

An Operational profile is a Complete set of commands with their probabilities of occurrence

System Testers and System engineers are included

3.Define “Just Right” Reliability

Define what “failure” means for the product– Failure is defined as any Departure of system Behavior in

execution from user needs– Failure intensity is the number of Failures per unit time

Choose a common Measure for all failure intensities, either Failures per some natural unit or Failures per hour

Set the total system Failure Intensity Objective (FIO) for each associated System – using Field data like Customer Satisfaction surveys related

to measured failure intensity, – an analysis of competing products balancing among major

quality characteristics users need.

Finding a developed software failure intensity objective for any software you develop plus choosing among software reliability strategies to meet the developed software

4.Prepare for Test Specify the new Test cases for new operations of base

product and variation for current release based on

operation profile

Prepares Test procedures to execute load tests

5.Execute Test determine an allocated Test time among Feature test,

Load test, and Regression test, invoke test and identity

system failure along with when they occur

• Feature tests – Interactions and Effects of the field environment minimized

• Load tests- execute Test cases simultaneously, with full interactions and all the effects of the Field environment

• Regression test-executes some or all feature tests and it is designed to reveal failures caused by faults introduced by program changes

6.Guiding Test

Involves guiding the product’s system Test phase and Release

Failure data is interpreted differently for software we are developing and software we acquire. We attempt to remove the faults that are causing Failures

For developed software, we estimate the FI/FIO ratio from the times of failure events or the number of failures per time interval, using reliability estimation programs such as CASRE (Computer Aided Software Reliability estimation)

Thank You

Dr. Himanshu HoraSRMS College of Engineering & Technology

Bareilly (INDIA)