embryology cvs part i

Understanding Nonfunctional Requirements - 1


Get Your Users “IN” the Doghouseand Keep Yourself Out:

Eliciting Nonfunctional Requirements


Who is Roxanne Miller?

Requirements Quest® founder.• IIBA Endorsed Education Provider• Requirements management

process improvement

Certified Business AnalysisProfessional (IIBA).

Keynote speaker at BusinessAnalyst World conferences.

Whoam I?

Self proclaimed ‘Requirements Super Freak’.


Where to get Roxanne's book

http://www.RequirementsQuest.com

The Quest for Software Requirements(book): http://www.requirementsquest.com/products/the-quest-for-software-requirements

Software Requirements Questions (CD or Download) -companion to the book that has the suggested questions in aMicrosoft Excel file:http://www.requirementsquest.com/products/softwarerequirements-questions-download

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Session Learning Objectives

Understandthese vital, yet

overlookedrequirements

Classifycommon

nonfunctionalrequirements

Definenonfunctionalrequirements

What toExpect


Nonfunctional Definition

Objective#1


#1


Levels of Requirements

Business LevelDefines project scope.Identifies business benefitsand high-level objectives.

Focuses on business processesinformation and materials.

Names user roles and goals.User Level

Processing inputs and outputs.Defines functions, features,

and the environment.System Level

Levels


Nonfunctional in Context

BusinessRequirements

UserRequirements

SystemRequirements

(Functional & Nonfunctional)

Sponsor point of view Scope of the project Business objectives User point of view User goals User inputs and

outputs Functional—what the

system does Nonfunctional—how

well the system does it

High-level

Detailed

Levels


Oh No, Not Nonfunctional

FunctionalRequirements

NonfunctionalRequirements

Bucket1

Bucket2

“A nonfunctional requirement is anythingthat is not functional.” NOT!

Whatit’s NOT


A Handful of Definitions

“Nonfunctional requirement – in software system engineering, a software requirement that describesnot what the software will do, but how the software will do it, for example, software performancerequirements, software external interface requirements, software design constraints, and softwarequality attributes. Nonfunctional requirements are difficult to test; therefore, they are usually evaluatedsubjectively.” [Thayer2000]

“Non-functional requirements – These are constraints on the services or functions offered by thesystem. They include timing constraints, constraints on the development process and standards.Non-functional requirements often apply to the system as a whole. They do not usually just apply toindividual system features or services.” [Sommerville2007]

“Non-functional requirement – A property, or quality, that the product must have, such as anappearance, or a speed or accuracy property.” [Robertson2003]

“Nonfunctional requirement – A description of a property or characteristic that a software system mustexhibit or a constraint that it must respect, other than an observable system behavior.” [Wiegers2003]

“Nonbehavioral requirements – Requirements that describe the required overall attributes of thesystem, including portability, reliability, efficiency, human engineering, testability, understandability, andmodifiability.” [Davis1993]

Example


What if we removed…

General wordiness. Nonfunctional “examples.” “Descriptive” information that

doesn’t add value. Inclusion or reference to

“functional requirements.”

ScaledDown


What Does It Really Mean?

…how the software will do it.

…constraints on the services or functionsoffered by the system....property, or quality, that the productmust have.…property that a software system mustexhibit or a constraint that it must respect.…required overall attributes of the system.

What’sleft?


A Simplified Definition

NonfunctionalRequirement –

a specification ofhow well

a software systemmust function.

HowWell


F Product features.F Describe the

actions with whichthe user work isconcerned.

F Characterized byverbs (active).

N Product properties.N Describe the

experienceof the user whiledoing the work.

N Characterized byadjectives.

Functional vs. Nonfunctional Differ


Vital, Yet Why Overlooked?

Objective#2

Understand whynonfunctionalrequirements

are vital,yet overlooked

#2


Importance of Nonfunctional

All functional requirements may be satisfied, but

if nonfunctionalrequirementsare overlooked,the systemwill fail.

NeedBoth


Nonfunctional Challenges

No agreed upon formal definition. No complete list. No single universal

classification scheme. Different people and organizations

use different terminologies.

Don’tAgree


Alternative Names

Quality Attributes. Quality Requirements. Nonbehavioral Requirements. “ilities” or “ities.” Spelled with or without a hyphen.

• Non-functional or Nonfunctional

ManyNames


Nonfunctional Complexity

Relative

ComplexNature

Integrated

Subjective


Nonfunctional Classification

Objective#3

Making sense ofnonfunctional

requirements witha user-focusedclassification

#3


Access ControlAccessibilityAccountabilityAccuracyAdaptabilityAdditvityAdjustabilityAffordabilityAgilityAuditabilityAugmentabilityAutonomyAvailabilityBuffer Space*CapabilityCapacityClarityCode Space*CohesivenessCommonalityCompatibilityCompletenessComprehensibilityConceptualityConcisenessConfidentialityConfigurabilityConnectivityConsistency

ControllabilityCoordination CostCoordination TimeCorrectnessCouplingCustomer EvaluationCustomer LoyaltyCustomizabilityData Space*DecomposabilityDegradation of ServiceDependabilityDevelopment CostDevelopment TimeDistributivityDiversityEase of useEfficiencyElasticityEnhanceabilityEvolvailityExecution CostExtensibilityExternal ConsistencyFault ToleranceFeasibilityFlexibilityFormalityGenerality

Human EngineeringIndependenceInformativenessIntegrityInternal ConsistencyInteroperabilityIntuitivenessLearnabilityLeveragabilityMain Memory*MaintainabilityMaintenance CostMaintenance TimeMaturityMean PerformanceMeasurabilityMobilityModifiabilityModularityNaturalnessNomadicityObservabilityOff-Peak Period*OperabilityOperating CostPeak Period*PerformabilityPlanning CostPlanning Time

PortabilityPrecisionPredictabilityProcess Mgmt. TimeProductivityProject StabilityProject Tracking CostPromptnessQualityReconfigurabilityRecoverabilityRecoveryReliabilityRepeatabilityReplaceabilityReplicabilityResponse TimeResponsivenessRetirement CostReusabilityRisk Analysis CostRisk Analysis TimeRobustnessSafetyScalabilitySecuritySensitivitySimilaritySimplicity

Space BoundednessSpace PerformanceSpecificityStabilitySubjectivitySupportabilitySuretySurvivabilitySusceptibilitySustainabilityTanknessTestabilityThroughputTimelinessTraceabilityTrainabilityTransferabilityTransparencyUnderstandabilityUniform*UniformityUsabilityUser-FriendlinessValidityVariabilityVerifiabilityVersatilityVisibility*Performance

Overwhelmability? ScaryList?


What are the User Needs?

Operation How well does the systemoperate for daily use bythe user?

Revision How easy is it to correcterrors and add functions?

Transition How easy is it to adapt tochanges in the technicalenvironment?

UserFocus


A User-Focused Classification

Based on [McCall 1980] [Deutsch 1988] [Keller 1990]

UserFocus

User Concern Nonfunctional

How well is it safeguarded against unauthorized access? Access Security

How dependable is it during normal operating times? Availability

How fast, how many, and how well does it respond? Efficiency

How accurate and authentic is the data? Integrity

How immune is the system to failure? Reliability

How resilient is the system from failure? Survivability

How easy is it to learn and operate the system? Usability

How easy is it to modify to work in different environments? Flexibility

How easy is it to upkeep and repair? Maintainability

How easy is it to expand or upgrade its capabilities? Scalability

How easy is it to show it performs its functions? Verifiability

How easy is it to interface with another system? Interoperability

How easy is it to transport? Portability

How easy is it to convert for use in another system? Reusability

Ope

ratio

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Tran

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The extent to which the system issafeguarded against deliberateand intrusive faults from internaland external sources.

User concern• How well is the system

safeguarded againstunauthorized access?

Operation: Access Security


The degree to which users candepend on the system to be up(able to function) during “normaloperating times.”

User concern• How dependable is

the system duringnormal operating times?

Operation: Availability


The extent to which the softwaresystem handles capacity,throughput, and response time.

User concern• How fast does it process

(capacity)? How manyat a time (throughput)?Response time?

Operation: Efficiency


Operation: Integrity

The degree to which the datamaintained by the software systemare accurate, authentic,and without corruption.

User concern• How accurate and

authentic are the data?


The extent to which the softwaresystem consistently performs thespecified functions without failure.

User concern• How immune is

the system to failure?

Operation: Reliability


The extent to which the softwaresystem continues to function andrecovers in the presence of asystem failure.

User concern• How resilient is

the systemfrom failure?

Operation: Survivability


The ease in which the user is ableto learn, operate, prepare inputsand interpret outputs throughinteraction with a system.

User concern• How easy is it to

learn and operatethe system?

Operation: Usability


The ease in which the softwarecan be modified to adapt todifferent environments.


change and addnew features?

Revision: Flexibility


The ease in finding and fixingfaults in the software system.

User concern• How easy is it

to upkeepand repairthe system?

Revision: Maintainability


Revision: Scalability

The degree in which the softwaresystem is able to expand itsprocessing capabilities upward andoutward to support business growth.


expand or upgradethe capabilitiesof the system?


The extent to which tests,analysis, and demonstrations areneeded to prove that the softwaresystem will function as intended.


to show it performsits functions?

Revision: Verifiability


Transition: Interoperability

The extent to which the softwaresystem is able to couple orfacilitate the interface with othersystems.


to interface withanother system?


The ease in which a softwaresystem from its current hardwareor software environment can betransferred to anotherenvironment.

User concern• How easy is

it to transport?

Transition: Portability


The extent to which a portion ofthe software system can beconverted for use in another.


to convert for usein another system?

Transition: Reusability


Session Learning Objectives

Classifycommon

nonfunctionalrequirements

Understandthese vital, yet

overlookedrequirements


Recap


Get Roxanne’s Book UsefulTool

Probing questionsto bring nonfunctional

requirements into focus;Proven techniques

to get the rightstakeholder involvement.


2,000+ Suggested Questions UsefulTool

Sort and filter accordingto your needs.

Change thewording to suiteyour personal style.

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Questions

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Presented by: Roxanne E. Miller, CBAPwww.RequirementsQuest.com

ThankYou

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