The Cornerstones of Enterprise Architecture: Greefhorst, Proper

204 Pages·2011·3.528 MB·English

by  Principles, Architecture

The Enterprise Engineering Series
SeriesEditors
JanL.G.Dietz
ErikProper
JoséTribolet
EditorialBoard
TerryHalpin
JanHoogervorst
MartinOp’tLand
RonaldG.Ross
RobertWinter
Forothertitlespublishedinthisseries,goto
www.springer.com/series/8371
Danny Greefhorst (cid:2) Erik Proper
Architecture
Principles
The Cornerstones
of Enterprise Architecture
DannyGreefhorst ErikProper
ArchiXLB.V. PublicResearchCentreHenriTudor
NijverheidswegNoord60-27 29,avenueJohnF.Kennedy
Amersfoort3812PM 1855Luxembourg-Kirchberg
TheNetherlands Luxembourg
[email protected] [email protected]
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Foreword
Whenenterprisearchitectstrytoexplaintopeoplewhoarenotenterprisearchitects
what it is they do for a living, they almost invariably resort to using an analogy
with the architecture of buildings, and describe enterprise architecture as a ‘kind
of blueprint’. While this analogy may be helpful in conveying a general sense of
what the discipline of enterprise architecture is ‘sort of like’, it can be seriously
misleadingiftakentooliterally.
Despite this risk, far too much thinking about enterprise architecture has been
undulyinfluencedbythisanalogy.Thisisnotsurprising;afterall,itiscalled‘archi-
tecture’,anditisreasonabletoexpectthatiftwodisciplinesshareanimportantpart
oftheirname,theymustsharealotofotherstuffaswell.Unfortunately,theydonot.
Buildingsandenterprisesarequalitativelydifferentkindsofartifacts.Probablythe
biggestdifferenceisthewaypeoplerelatetothem.Peopledonotjustuseorinteract
withanenterprise:peoplearetheenterprise.
Minimizing,ifnotentirelyignoring,thisdifference,whetherdeliberatelyorin-
advertently,makestheproblemofenterprisedesignseemtractable,inthatitcanbe
thoughtofasamatterofdraftingtherightkindofblueprint.Hence,mostdefinitions
of architectureas appliedto what must be thought of as people-intensivesystems,
areinherentlystructuralinnature,andarchitecturesarethoughtofasbeingderived
viaandrepresentedbymodels.Theideathatarchitectureisprimarilyaboutstruc-
ture,andtheideathatarchitectureisbestrepresentedbymodels,mutuallyreinforce
oneanother.Mostarchitecturalmodelsarerepresentedby‘boxesandlines’,andit
ishardnottothinkofwhatisdepictedassomekindofstructure.
This is ironic, because the earliest well documented use of the word ‘architec-
ture’inanITcontextwastodescribetheprogrammervisiblebehavioroftheIBM
System/360familyofprocessors,inamannerindependentoftheinternalstructure
oftheimplementation.
Theemphasis,ifnotexclusivefocus,onstructureastheconcernofarchitecture
leadstoanevenmoreperniciousconsequence:divorcingthearchitectureofasys-
temfromitsraisond’être.Modelsareverygoodatrepresentingthewhatandhow
ofasystem,buttheyleavethewhyimplicitandexternaltothemodel,andthus,too
often,externaltothearchitecture.Thismakesitfartooeasytothinkofthesystem
asanendinitself,ratherthanasameanstoachievingsomemission.
v
vi Foreword
When I joined the Architecture Profession Office of HP Services in 2001,
I learned HP’s architecture method, which later became known as HP Global
Method for IT Strategy and Architecture (ITSA). Until then I had been doing ar-
chitecturebytheseatofmypants,andITSAwasarevelation.TheessenceofITSA
isusingalinkedsuccessionofarchitecturalprinciplestoprovideachainofmotiva-
tionandjustificationfromthebusinesscontextoftheproblem,needoropportunity
totheconstraintsonimplementationandoperationnecessarytoensurethesolution
delivers the required business value. In ITSA, models, while important, are sec-
ondarytoprinciples;indeed,ITSApractitionersaretaughtthatmodelsarederived
from principles, and ideally every element of a model illustrates some principle.
Thischainofmotivationandjustificationnotonlyensuresalignmentofthesolution
withtheneedsofthebusiness,italsoprovidestraceabilityandanobjectivecontext
forgovernance.
TherecentlypublishedbookabouttheITSAmethodshowedtheimportantrole
principlescanplayinthedevelopmentofanarchitecture.ThisnewbookbyDanny
andEriktakesthenextstepbyprovidinganindepthtreatmentofprinciples,anda
conceptualframeworkforthinkingaboutthem.Architecturalprinciplesarefinally
getting the well deserved attention they have too long lacked. I am confident that
somedaywewilllookbackonthisasawatershedeventintheprofessionalization
andmaturingofthedisciplineofenterprisearchitecture.
LeonardFehskens
VP,SkillsandCapabilities
TheOpenGroup
Preface
Enterprises,fromsmalltolarge,evolvecontinuously.Asaresult,theirstructuresare
transformedandextendedcontinuously.Withoutsomemeansofdeliberatecontrol,
suchchangesareboundtoleadtoanoverlycomplex,uncoordinatedandheteroge-
neous environment that is hard to manage, while at the same time resisting future
changesindesireddirections.Enterprisearchitectureaimstoprovidesuchcontrols.
Keyconceptsinenterprisearchitectureincludestakeholdersandtheirconcerns,
architecture principles, models, views and frameworks. While most of these con-
ceptshaveobtainedampleattentioninresearch,theconceptofarchitectureprinci-
ples has not been studied much yet. More specifically,architecture principles pro-
vide a means to direct transformations of enterprises. As a consequence, it can be
arguedthatarchitectureprinciplesformthecornerstonesofanyarchitecture.Inthis
book, we therefore specifically focus on the role of architecture principles. It pro-
vides both a theoretical and a practical perspective on architecture principles. As
suchitistargetedatstudentsandresearchers,aswellaspractitionerswhohavethe
desiretounderstandthefoundationsunderlyingtheirpracticalwork.
Thetheoreticalperspectiveinvolvesabriefsurveyofthegeneralconceptofprin-
ciple as well as an analysis of different flavors of principles. A key distinction is
made between scientific principles and normative principles. Scientific principles
arelawsorfactsofnatureandformthefundamentaltruthsthatonecanbuildupon.
Normativeprinciplesarerulesofconductthatguide/restrictbehavior.Whilescien-
tificprincipleshold“naturally”,normativeprinciplesneedexplicit“enforcement”.
Architectureprinciples,beingthecoretopicofthisbook,areregardedasaspecific
classofnormativeprinciplesthatinfluence/directthedesignofanenterprise(from
thedefinitionofitsbusinesstoitssupportingIT).
The practical perspective on architecture principles is concerned with an ap-
proach for the formulation of architecture principles, as well as their actual use in
organizations.Toillustratetheiruseinpractice,severalreallifecasesarediscussed.
Furthermore, the book includes an appendix, which provides a discussion on how
to use the suggested approach for the formulation and application of architecture
principles in the context of The Open Group’s TOGAF, as well as a catalogue of
examplearchitectureprinciples.
vii
Acknowledgements
Thecreationofthisbookwouldnothavebeenpossiblewithoutthecontributionof
others. In particular, many of the ideas have been based on discussions we had in
the architecture principles working group of the Netherlands Architecture Forum
(NAF). We would especially like to thank Louis Dietvorst and Pieter Buitenhuis
fortheirvaluablecontributions.OurthoughtsarealsowithLeoHermans,whocon-
tributedenthusiasticallytotheworkinggroup,buthasregretfullypassedaway.We
alsothankthestudentswhojoinedtheworkinggroupandcontributedtotheconcep-
tualframeworkwiththeirmasterthesis:MartijnvandenTillaart,KoenvanBoekel,
NielsvanBokhoven,TeunHuijbers,HarryvandenWollenbergandJordyKersten.
We would also like to thank the people that contributed content to the book,
such as case descriptions. Our book would not have been as valuable without the
contributionsofCharlesHendriks,JoostPeetoom,ErikKiel,AnneMarievanRooij,
RonaldvandenBerg,PeterBergman,ErikSaaman,BennyPrijandLouisDietvorst.
Wealsothankallthepeoplethatrevieweddraftversionsofthebookandprovided
us with important feedback: Christian Fischer, Dirck Stelzer, Eric Schabell, Erik
Vermeulen,ErikSaaman,ErwinOord,FrankHarmsen,JanDietz,JanHoogervorst,
Joost Lommers, José Tribolet, Marc Lankhorst, Mathias Ekstedt, Monika Grün-
wald,PeterBeijer,PontusJohnson,RaymondSlotandRemcodeBoer.Veryspecial
thanksgotoJoostLommersandPeterBeijerfortheirelaboratereviewcomments.
WewouldliketoexplicitlythankLenFehskensforbeingasourceofinspirationfor
ourbook,forprovidinginsightsontheessenceofarchitecture,andforwritingthe
foreword.
Finally, we would also like to thank our respective employers, ArchiXL, The
NetherlandsandthePublicResearchCentreHenriTudor,Luxembourg,aswellas
theFondsNationaldelaRechercheLuxembourgandtheNetherlandsArchitecture
Forum,insupportingthecreationandpublicationofthisbook.
Amersfoort,TheNetherlands DannyGreefhorst
Luxembourg-Kirchberg,Luxembourg ErikProper
ix
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 ChallengestoEnterprises . . . . . . . . . . . . . . . . . . . . . . 1
1.2 EnterpriseArchitectureandArchitecturePrinciples . . . . . . . . 3
1.3 MotivationsandTargetAudience . . . . . . . . . . . . . . . . . 4
1.4 OutlineoftheBook . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 TheRoleofEnterpriseArchitecture . . . . . . . . . . . . . . . . . . 7
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 EnterpriseTransformationsandEnterpriseEngineering . . . . . . 9
2.3 StreamsofActivitiesinEnterpriseEngineering . . . . . . . . . . 11
2.4 Architecture-BasedGovernanceofEnterpriseTransformations . . 14
2.4.1 TheNeedforArchitecture . . . . . . . . . . . . . . . . . 14
2.4.2 ArchitectureasaBridgefromStrategytoDesign . . . . . 16
2.4.3 SteeringwithArchitecture . . . . . . . . . . . . . . . . . 18
2.4.4 TheThreeRolesofEnterpriseArchitecture . . . . . . . . 19
2.5 DefiningEnterpriseArchitecture . . . . . . . . . . . . . . . . . . 20
2.5.1 ThePurposeofanEnterpriseArchitecture . . . . . . . . . 21
2.5.2 TheMeaningofanEnterpriseArchitecture . . . . . . . . 22
2.5.3 TheElementsofanEnterpriseArchitecture . . . . . . . . 22
2.5.4 DefinitionofEnterpriseArchitecture. . . . . . . . . . . . 24
2.6 OtherFormsofArchitecture . . . . . . . . . . . . . . . . . . . . 24
2.7 StandardsforEnterpriseArchitecture . . . . . . . . . . . . . . . 26
2.8 TheRoleofArchitecturePrinciples . . . . . . . . . . . . . . . . 28
2.9 KeyMessages. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3 AConceptualFrameworkforPrinciples . . . . . . . . . . . . . . . . 31
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 BackgroundofArchitecturePrinciples . . . . . . . . . . . . . . . 32
3.3 KeyClassesofPrinciples . . . . . . . . . . . . . . . . . . . . . . 34
3.3.1 ScientificPrinciples . . . . . . . . . . . . . . . . . . . . 34
3.3.2 DesignPrinciplesasNormativePrinciples . . . . . . . . . 35
3.3.3 FromCredostoNorms . . . . . . . . . . . . . . . . . . . 38
xi
xii Contents
3.3.4 ConceptualFramework . . . . . . . . . . . . . . . . . . . 40
3.4 ArchitecturePrinciplesasPillarsfromStrategytoDesign. . . . . 44
3.4.1 ArchitecturePrinciples . . . . . . . . . . . . . . . . . . . 44
3.4.2 BusinessandITPrinciples . . . . . . . . . . . . . . . . . 44
3.4.3 BridgingfromStrategytoDesign . . . . . . . . . . . . . 46
3.4.4 ExtendedConceptualFramework . . . . . . . . . . . . . 48
3.5 MotivatingArchitecturePrinciples . . . . . . . . . . . . . . . . . 49
3.5.1 SourcesforFindingMotivation . . . . . . . . . . . . . . 50
3.5.2 DriversasMotivationforArchitecturePrinciples . . . . . 52
3.5.3 ExtendedConceptualFramework . . . . . . . . . . . . . 54
3.6 FormalSpecificationofNormativePrinciples . . . . . . . . . . . 56
3.7 KeyMessages. . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 ArchitecturePrincipleSpecifications . . . . . . . . . . . . . . . . . . 59
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.2 DimensionsinArchitecturePrinciples . . . . . . . . . . . . . . . 62
4.2.1 TypeofInformationDimension . . . . . . . . . . . . . . 63
4.2.2 ScopeDimension . . . . . . . . . . . . . . . . . . . . . . 63
4.2.3 GenericityDimension . . . . . . . . . . . . . . . . . . . 64
4.2.4 LevelofDetailDimension(s). . . . . . . . . . . . . . . . 65
4.2.5 StakeholderDimension . . . . . . . . . . . . . . . . . . . 66
4.2.6 TransformationDimension . . . . . . . . . . . . . . . . . 66
4.2.7 QualityAttributeDimension . . . . . . . . . . . . . . . . 67
4.2.8 Meta-levelDimension . . . . . . . . . . . . . . . . . . . 69
4.2.9 RepresentationDimension . . . . . . . . . . . . . . . . . 69
4.3 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.3.1 BasicStructure . . . . . . . . . . . . . . . . . . . . . . . 71
4.3.2 AdvisedAttributes . . . . . . . . . . . . . . . . . . . . . 73
4.3.3 AttributesforClassification . . . . . . . . . . . . . . . . 75
4.3.4 PotentialAttributes . . . . . . . . . . . . . . . . . . . . . 75
4.3.5 GenericMeta-dataAttributes. . . . . . . . . . . . . . . . 76
4.3.6 Relationships . . . . . . . . . . . . . . . . . . . . . . . . 77
4.4 ArchitecturePrincipleSets . . . . . . . . . . . . . . . . . . . . . 79
4.5 QualityCriteria . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.6 KeyMessages. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5 APracticalApproach . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.2 GenericProcess . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5.2.1 DetermineDrivers . . . . . . . . . . . . . . . . . . . . . 88
5.2.2 DeterminePrinciples . . . . . . . . . . . . . . . . . . . . 91
5.2.3 SpecifyPrinciples . . . . . . . . . . . . . . . . . . . . . 98
5.2.4 ClassifyPrinciples . . . . . . . . . . . . . . . . . . . . . 100
5.2.5 ValidateandAcceptPrinciples . . . . . . . . . . . . . . . 100
5.2.6 ApplyPrinciples . . . . . . . . . . . . . . . . . . . . . . 101
5.2.7 ManageCompliance . . . . . . . . . . . . . . . . . . . . 105