iisc - proficience - sqam - module 1

8/14/2019 IISc - Proficience - SQAM - Module 1

1/27

SQAM Course, Proficience, IISc 1

Module 1Module 1

Introduction to SoftwareIntroduction to SoftwareQualityQuality


2/27


Different Views on QualityDifferent Views on Quality

Hard to define, Impossible to measure and Easy torecognize

Transparent when present, but easily recognized inabsence

Quality is not absolute

Quality is multidimensional

Quality is subject to constraintsQuality is about acceptable compromises

Quality Criteria are not independent, but interactwith each other


3/27


Garvins Five Definitions ofGarvins Five Definitions of

QualityQuality Transcendent Definition (Relative Quality): Quality is universally

recognizable; it is related to a comparison of features andcharacteristics of products.

Product-Based: Quality is a precise and measurable variable.Differences in quality reflect differences in quantity of some productattribute.

User-Based Definition: Quality is fitness for intended use.

Manufacturing-Based Definition: Quality is conformance tospecifications.

Value-Based Definition: Quality is defined in terms of costs andprices. A quality product is one that provides performance at anacceptable price or conformance at an acceptable costs.


4/27


Quality Revolution or Quality Confusion?Quality Revolution or Quality Confusion?


5/27


Poor Quality Practice Results inPoor Quality Practice Results in


6/27


Some Definitions..Some Definitions..

ISO: The totality of features and

characteristics of a product or service that

bear on its ability to satisfy specified orimplied needs

Fruhauf (1994): Quality is when the customer

comes back, not the product


7/27


Software QualitySoftware QualityThe degree to which a software product posses a

specified set of attributes necessary to fulfill astated purpose(Reifer,1985)

Conformance to customer expectations (StephenKan,1995)

Software product must provide functions of a typeand at a time when the user needs them. If it does

not, nothing else matters. The product must workconsistently and reasonably, without which theuser will not use it regardless of its other bestattributes.( Watts Humprey, 1995)


8/27


GE Model (McCall,1977)GE Model (McCall,1977)

Product Revision:

2. Maintainability

3. Flexibility

4. Testability

Product Transition:

2. Portability

3. Reusability

4. Interoperability

Product Operations:

2. Correctness

3. Reliability

4. Efficiency

5. Integrity

6. Usability


9/27


Software Quality FactorsSoftware Quality Factors

Product Operations

Correctness Extent to which a program satisfies its

specification and fulfills the users

functional requirements

Does it do what I want?

Reliability Extent to which a program can beexpected to perform its intended

functions with required precision

Does it behave properly all the time?


10/27


Product Operations (continued)Efficiency The amount of computing resources

required by a program to perform its functions

Will it run fast?Integrity Extent to which access to software or data

by unauthorized persons can be controlled

Is it secure?

Usability Effort required to learn, operate, prepareinput, and interpret output of a program

Can I run it easily?



11/27


Product RevisionMaintainability Effort required to locate and fix

an error in an operational program

Can I fix it?Testability Effort required to test a program

to ensure it performs its intended

functions

Can I test it?Flexibility Effort required to modify an

operational program

Can I change it?



12/27


Product Transition

Portability Effort required to transfer an program from one

hardware configuration or software system

environment to another

Can it run on another machine?

Reusability Effort to which a program can be used in other

applications

Can I reuse part of the software?Interoperability Effort required to couple one system with another

Can it interface with another system?



13/27


Interaction between quality parametersInteraction between quality parameters

oXooooooooUser friendliness

oooCost/BenefitoooXoooooXoUser flexibility

oAppeal

XoXoooXXXooTime to use

XXXXXXXXXXXXoXTimeliness

oooooXooooAccuracy

oooooXoooooooUser Consultation

XooooXoooooXoPortability

oooooXXXooEase of Interfacing

XoXoXXooooooXoFlexibility

ooooXXooooooXoUnderstandability

XoXooXXXoXSecurity

oXooXXXoXIntegrity

XoXXXoXXXXXXXoEfficiency

oooooooooooooReliability

OCUATTAUPEIFUSIERCriteria


14/27


Process and product qualityProcess and product quality

The quality of a developed product is influenced

by the quality of the production process.

This is important in software development as some

product quality attributes are hard to assess.However, there is a very complex and poorly

understood relationship between software

processes and product quality.


15/27


Software Quality AssuranceSoftware Quality Assurance

Activity of providing to all concerned the

evidence needed to establish confidence that the

quality function is being performed adequately(Juran,1995)

Quality Assurance is a planned and systematic

pattern of all actions necessary to provide

adequate confidence that an item or productconforms to established technical requirements

(IEEE,1990)


16/27


Software Quality Assurance ActivitiesSoftware Quality Assurance Activities

Monitoringprocesses andproducts throughout thesoftware development lifecycle to ensure the quality of thedelivered product(s)

Monitoring the processes

Provides management with objective feedbackregarding process compliance to approved plans,procedures, standards, and analyses

Monitoring the products Focus on the quality of product within each phase of

the SDLC e.g., requirements, test plan, architecture, etc.

Objective: identify and remove defects throughout thelifecycle, as early as possible


17/27


Process AssessmentProcess Assessment

Use of standards and process models has a positive impact onthe quality of the software product

Disciplined, controlled development process

Examples include:

ISO 9001 CMMI

CMU SEI, 5 levels

SPICE

Developing a standard for software process assessment

ISO joint committee, Europe, Australia

IEEE 12207


18/27


Product AssessmentProduct Assessment

Reviews, inspections, walkthroughs, reports, standards

Requirements, analysis, architecture, detailed design

model, test cases

Issue or problem reports

Metric reports

Traceability reports

Documentation, coding standards


19/27


Microsoft ViewMicrosoft View Have you identified important quality characteristics to

your project?

Have you made others aware of projects qualityobjectives?

Have you differentiated between External an Internalquality characteristics?

Do you use different error detection techniques?

Do you have a plan to assure quality at each stage ofsoftware development?

Is quality measured to say whether it is improving anddegrading?

(Jim McCarthy, Microsoft Press, 1995)


20/27


21/27


Software Quality ControlSoftware Quality Control

Involves series of inspections, reviews and

tests used throughout the software process.

Measurement and feedback loop is

important

Activities can be completely automated,

entirely manual or combination of both.


22/27


Verification and ValidationVerification and Validation

Verification is the process of evaluating a system

to determine whether the products of a given

development phase satisfy the conditions imposedat the start of that phase.

Validation is the process of evaluating a system or

component during or at the end of development

process to determine whether it satisfies specifiedrequirements


23/27


Software quality managementSoftware quality managementConcerned with ensuring that the required level of

quality is achieved in a software product.

Involves defining appropriate quality standards

and procedures and ensuring that these arefollowed.

Should aim to develop a quality culture where

quality is seen as everyones responsibility.


24/27


Define process standards such as how reviewsshould be conducted, configurationmanagement, etc.

Monitor the development process to ensurethat standards are being followed.

Report on the process to project management andsoftware procurer.

Dont use inappropriate practices simply becausestandards have been established.

Practical process qualityPractical process quality


25/27


Typical SQA Role in the organizationTypical SQA Role in the organization

Responsibility for SQA planning, oversight,recording, analysis and reporting.

Prepare an SQA plan for a project

Participate in the development of projects processdescription

Reviews Software Engineering activities to verifycompliance with defined software process

Audits the designated software work productsEnsures deviations are recorded and closed

Reports to Senior Management


26/27



27/27


Case AnalysisCase Analysis

Compare ISO 9126 and ISO 12207

How they are related?

To be presented in the next class

Thank you

iisc - proficience - sqam - module 1

Documents