Addison wesley understanding dot NET 2nd edition may 2006 ISBN 0321194047

Understanding.NET,SecondEdition
ByDavidChappell
...............................................
Publisher:AddisonWesleyProfessional
PubDate:May15,2006
PrintISBN-10:0-321-19404-7
PrintISBN-13:978-0-321-19404-6
Pages:336

TableofContents|Index

Microsoft's.NETisrevolutionizingWindows-basedsoftwaredevelopment.Sinceitsinitial
releasein2002,.NEThaschangedsignificantly,becomingthefoundationforanew
generationofWindowsapplications.The.NETFrameworkandVisualStudio,thetwocore
aspectsofthisinitiative,provideamultilanguageenvironmentinwhichdeveloperscan
createWebservices,graphicaluserinterfaces,andotherkindsofapplications.Takenasa
whole,the.NETtechnologieshavechangedthewaynearlyeveryWindowsapplicationis
built.
Nowfullyupdatedforversion2.0ofthe.NETFrameworkandVisualBasic2005,
Understanding.NET,SecondEdition,isaconciseguidetothelandscapeofWindows
development.Marginnotes,detaileddiagrams,andlucidwritingmakethisbookeasyto
readandnavigate,whileanalysissectionsexplorecontroversialissuesandaddress
commonconcerns.DavidChappell'sindependentperspectiveandstraightforward
descriptionsclarifybothhowthe.NETtechnologiesworkandhowtheycanbeused.
Coverageincludes
Anoverviewof.NETanditsgoals
TheCommonLanguageRuntime(CLR)
The.NETlanguages,includingC#,VisualBasic,andC++
The.NETFrameworkclasslibrary
BuildingWebApplicationswithASP.NET
AccessingDatawithADO.NET

.NETframeworkintegrationwithSQLServer2005
Thekeytousinganewtechnologyistounderstandthefundamentals.Thisbookprovides
therobustfoundationdevelopersandtechnicalmanagersneedtomaketherightdecisions


andmaximizethepotentialofthisrevolutionaryframework.


Understanding.NET,SecondEdition
ByDavidChappell
...............................................
Publisher:AddisonWesleyProfessional
PubDate:May15,2006
PrintISBN-10:0-321-19404-7
PrintISBN-13:978-0-321-19404-6
Pages:336

TableofContents|Index

Copyright
PraiseforDavidChappell'sUnderstanding.NET,SecondEdition
IndependentTechnologyGuides
Preface
Chapter1.Introducing.NET
The.NETFramework
VisualStudio2005
Conclusion
Chapter2.TheCommonLanguageRuntime
BuildingManagedCode:TheCommonTypeSystem
CompilingManagedCode
OrganizingManagedCode:Assemblies
ExecutingManagedCode
Conclusion
Chapter3..NETLanguages
C#
C++
Conclusion
Chapter4.Surveyingthe.NETFrameworkClassLibrary
AnOverviewoftheLibrary
FundamentalNamespaces
Conclusion
Chapter5.BuildingWebApplications:ASP.NET
ASP.NETApplications:Basics

ASP.NETApplications:BeyondtheBasics
Conclusion
Chapter6.AccessingData:ADO.NET
Using.NETFrameworkDataProviders
UsingConnectionandCommandObjects
AccessingDatawithDataReaders

AccessingDatawithDataSets
Conclusion
Chapter7.BuildingDistributedApplications
ASP.NETWebServices:System.Web.Services
.NETRemoting:System.Runtime.Remoting
EnterpriseServices:System.EnterpriseServices
FinalThoughts
AbouttheAuthor
Index


Copyright
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Includesbibliographicalreferencesandindex.
ISBN0-321-19404-7(pbk.:alk.paper)
1.Microsoft.NETFramework.2.Internetprogramming.3.Computersoftw

QA76.76.M52C482006
005.2'768dc22
Copyright©2006DavidChappell
Allrightsreserved.PrintedintheUnitedStatesofAmerica.This
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Dedication
ToAvaandLauren,jewelsinthenight.




PraiseforDavidChappell's
Understanding.NET,SecondEdition
"DavidChappell'sUnderstanding.NET,SecondEdition,
containsexcellentcoverageoftheCLR,classlibrary,
ASP.NET,ADO.NET,anddistributedapplications.Itisstill
thebesttechnicaloverviewof.NETtodate,andI
recommendittoanyonemakingthetransitionto.NET."
DaveCorun
DirectorofMicrosoftTechnologies
CatalystITServices
"David'scoverageofallthings.NETisextensiveand
thorough.EvenregularusersofVisualStudiowilllearn
somethingabout.NETthattheydidn'tknow."
HarryPierson
ArchitectureStrategyTeam
MicrosoftCorporation
"Understanding.NET,SecondEdition,willgivemanagers
theknowledgeandvocabularytheyneedtocommunicate
withtheirdevelopers.Developerslookingtoobtainahighlevelviewofthe.NETFrameworkbeforegoingintoeach
topicindepthwillalsobenefitfromthisbook.Thisbook

helpsdevelopersgetabird's-eyeviewof.NETFramework
beforetheyengageinthelonglearningcurverequired.
Thisbookisverywellorganizedandtechnicallyaccurate."
CesarBermudez
MCAD,MCSD,MCDBA,MCSA,MCSE,MCTS,MCT,A+,iNet+,CIW
President
DotNetArchitects,Inc.


"DavidChappellhasanastuteunderstandingofMicrosoft
technologyandanabilitytoexplaincomplexsystemsina
waythatisbothenticingandthoroughlyeducational.The
secondeditionofhisbook,Understanding.NET,shows
thatheremainsoneofthebesttechnologyauthorsinthe
business."
RichardMonson-Haefel
AuthorandSeniorIndustryAnalyst
BurtonGroup


IndependentTechnologyGuides
DavidChappell,SeriesEditor
TheIndependentTechnologyGuidesofferserioustechnical
descriptionsofimportantnewsoftwaretechnologiesofinterest
toenterprisedevelopersandtechnicalmanagers.Thesebooks
focusonhowthattechnologyworksandwhatitcanbeused
for,takinganindependentperspectiveratherthanreflectingthe
positionofanyparticularvendor.Theseareidealfirstbooksfor
developerswithawiderangeofbackgrounds,theperfectplace
tobeginmasteringanewareaandlayingasolidfoundationfor

furtherstudy.Theyalsogointoenoughdepthtoenable
technicalmanagerstomakegooddecisionswithoutdelvingtoo
deeplyintoimplementationdetails.
Thebooksinthisseriescoverabroadrangeoftopics,from
networkingprotocolstodevelopmentplatforms,andarewritten
byexpertsinthefield.Theyhaveafreshdesigncreatedto
makelearninganewtechnologyeasier.Alltitlesintheseries
areguidedbytheprinciplethat,inordertouseatechnology
well,youmustfirstunderstandhowandwhythattechnology
works.


TitlesintheSeries
BrianArkills,LDAPDirectoriesExplained:AnIntroductionand
Analysis,0-201-78792-X
DavidChappell,Understanding.NET:ATutorialandAnalysis,0201-74162-8
EricNewcomer,UnderstandingWebServices:XML,WSDL,
SOAP,andUDDI,0-201-75081-3


Preface
Writingtheprefaceforabook'ssecondeditionisfunitmeans
thatpeoplethoughtthefirsteditionwasusefulenoughto
warrantanupdate..NEThaschangedinsignificantwayssince
thisbookfirstappearedin2002,changesthatarereflectedin
thisnewedition.Sinceitsoriginalrelease,the.NETFramework
hasbecomethefoundationforanewgenerationofWindows
applications.Developersandthepeoplewhopaytheirsalaries
steppeduptothechallengeofadoptingthisnewenvironment,
andtheresulthasbeenbettersoftware.

Still,newpeoplecometo.NETeveryday.Likethefirstedition,
thegoalofthisbookistohelpdevelopersandtheirmanagers
understandthisbignewworld.

WhoThisBookIsFor
.NETishuge.Thereareplentyofbooksthatprovidedetailed
examinationsofeachfacetofthisenormoustechnologycrystal,
plentyofbookswithhardcore,hands-oninformation.Thisisn't
oneofthosebooks.Ibelievestronglythatunderstanding.NET
asawholeisessentialbeforedelvingmoredeeplyintoany
singlepartofthetechnology.Accordingly,mygoalhereisto
provideabroadoverviewofthe.NETtechnologies.
Ifyou'relookingforabig-pictureintroductiontothewholeof
.NET,thisbookisforyou.Whetheryou'readeveloperjust
gettingstartedwith.NET,atechnicalmanagerwhoneedsto
makedecisionsaboutthesetechnologies,orastudentseeing
someoftheseideasforthefirsttime,thisbookshouldbea
usefulguide.Thereisenoughdetailheretosatisfymanypeople
completely,whileotherswillusethisbookasastepping-stone
tomorespecificknowledge.Inanycase,Ihopethebook's
organizationandcontentmakeiteasierforyoutocometogrips


withthismassoftechnology.

FactandOpinion
Graspinganewtechnologyrequireslearningthefundamentals.
Whatareitsmainparts?Howdotheywork?Howdotheyfit
together?Butreallyunderstandingatechnologyrequiresmore
thanthis.Youneedtoknownotjusthowthingsworkbutalso

whythey'reimportant,howtheycomparetowhat'sgone
before,andwhatmighthappennext.
Thisbookaimsatprovidingallofthesethings.Inthetextitself,
I'vetriedhardtoremainstrictlytutorial,focusingsolelyon
describingwhat.NETis.Intheperspectiveboxes,Igivesome
broaderviewsonvariousaspectsofthetechnology.Inevery
case,theperspectiveexpressesmyviewofwhythingsarethe
waytheyareorwhatthefutureislikelytohold.Byseparating
theobjectivefromthesubjective,Ihopetomakeiteasierfor
youtodistinguishbetweenthetwo.Byprovidingopinionaswell
asfact,Ihopetomakethisbookbothmoreinterestingand
moreenlightening.

Acknowledgments
I'monceagainhumbledbythewillingnessofpeopletohelp
withprojectslikethis.Forthissecondedition,thanksgo
especiallytomyreviewers:HarryPiersonatMicrosoft,Richard
Monson-HaefeloftheBurtonGroup,andDaveCorunatCatalyst
ITServices.Theyallreadeverychapterandmademanyuseful
suggestions.ThanksalsotoRalphSquillaceandTedPattison,
whoansweredkeyquestionsatimportantmoments.Everybody
whohelpedwiththefirsteditiononceagainhasmyheartfelt
thanks:BobBeauchemin,KeithBrown,CoriDay,Ted
Demopoulos,BillEstrem,JeannineGailey,KitGeorge,Greg
Hack,RobHoward,MaximLoukianov,JuvalLöwy,Peter
McKiernan,YahyaH.Mirza,JohnD.Mitchell,Christophe


Nassare,EricNewcomer,DavidSceppa,AaronSkonnard,and
MikeWoodring.

AtAddison-WesleyI'mgratefultoElizabethPeterson,Stephane
Nakib,JanaJones,andKarenGettmanforallthey'vedonefor
meandfortheIndependentTechnologyGuidesseries.I'malso
thankfulfortheeffortsofKristinWeinberger,firstmyeditor,
nowmyfriendand(remarkably)neighbor,whooriginally
broughtmetoAddison-Wesley,andforthehardworkofNancy
Hendryx,thecopyeditorforthisedition.
Thelistofacknowledgementsinthisbook'sfirsteditionended
withDianaCatignani,pointingouthowmuchpoorermylife
wouldbewithouther.She'snowDianaChappell,motherofour
twobeautifuldaughters.Wordscannotexpressthepovertythat
wouldensuewereshenotmywife.
DavidChappell
SanFrancisco
March2006





1.Introducing.NET
What'srequiredtocreategoodsoftware?Whileit'spossibleto
writefirst-ratecodeinalmostanyenvironment,creatinggood
softwareismucheasierwhentherightplatformandtoolsare
available.FormostWindowsdeveloperstoday,thatplatformis
definedby.NET.Whiledefining.NETclearlywasoncea
challenge,it'snowclearthatthe.NETlabelrefersprimarilyto
twothings.Theyare:
The.NETFramework,whichconsistsoftheCommon
LanguageRuntime(CLR)andthe.NETFrameworkclass

library.TheCLRprovidesastandardfoundationforbuilding
applications,whilethe.NETFrameworkclasslibraryoffersa
largesetofstandardclassesandothertypesthatcanbe
usedbyany.NETFrameworkapplicationwritteninany
language.
VisualStudio,anintegrateddevelopmentenvironment
(IDE)forcreatingWindowsapplications.Whilethistoolcan
beusedtobuildsoftwarethatrunsdirectlyonWindows,its
mainfocusishelpingdeveloperscreate.NETFramework
applications.VisualStudiosupportsseveralprogramming
languagesforcreatingtheseapplications,includingC#[1],
VisualBasic(VB),andC++.
[1]Pronounced"Csharp,"asinthemusicalnote.

The.NETFrameworkandVisualStudioarethemaincomponentsof.NET


Perspective:.NET'sNamingJourney
Itmakessensetodaytothinkofthename".NET"asprimarilyreferringtothe
.NETFrameworkandVisualStudio.Thingsweren'talwayssosimple,however.
When.NETwasfirstannouncedinthesummerof2000,Microsoftappliedthe
termtoabroadrangeofthings.Today's.NETtechnologieswereincluded,of
course,butsowereseveralotherthings.ManyofMicrosoft'sserverproducts,
includingSQLServerandBizTalkServer,weregroupedtogetherasthe.NET
EnterpriseServers,forexample,andawhollyseparateefforteventuallyknown
as.NETMyServiceswaslaunched.Therewaseventalkaboutapossible
Windows.NETandOffice.NETsometimeinthefuture.
Butwasthereacommontechnicalunderpinningforallofthesethings?Sadly,
theanswerwasno.WhenMicrosoftfirstsprang.NETontheworld,ittreatedthe
termasabroadbrand,onethatcouldbeappliedtoprettymuchanythingthe

companywasdoing.TheresultwasagooddealofconfusionamongMicrosoft's
customers.
Thankfully,thestoryhasgottenmuchsimpler.The.NETEnterpriseServersare
nowconsideredpartoftheWindowsServerSystem,andsothey'velostthe.NET
tag..NETMyServicesfadedfromthescene,whilethebrandingboffinsin
Redmonddecidedagainsttackingthe.NETbrandontoeitherWindowsorOffice.
Today,whensomebodysays".NET,"they'rereferringtothe.NETFrameworkand
VisualStudio.

Variousversionsexistforbothofthesetechnologies.The
versionsdescribedinthisbookarethosereleasedbyMicrosoft
inlate2005:version2.0ofthe.NETFrameworkandVisual
Studio2005.




The.NETFramework
Theheartof.NETisthe.NETFramework.Firstreleasedin
2002,itbroughtenormouschangetothelivesofthosewho
writeWindowssoftwareandthepeoplewhomanagethem.
Figure1-1showstheFramework'stwomainparts:theCLRand
the.NETFrameworkclasslibrary.A.NETapplicationalways
usestheCLR,anditcanalsousewhateverpartsoftheclass
libraryitrequires.

Figure1-1.The.NETFrameworkconsistsofthe
CommonLanguageRuntime(CLR)andthe.NET
Frameworkclasslibrary.

The.NETFrameworkisafoundationforcreatingWindowsapplications


EveryapplicationwrittenusingtheFrameworkdependsonthe
CLR.Amongotherthings,theCLRprovidesacommonsetof
datatypes,actingasafoundationforC#,VB,andallother
languagesthattargetthe.NETFramework.Becausethis
foundationisthesamenomatterwhichlanguagetheychoose,
developersseeamoreconsistentenvironment.

TheCLRprovidesacommonbasisforall.NETlanguages


Perspective:The.NETFrameworkvs.theJavaEnvironment

Mainstreamsoftwaredevelopmenttodayhassplitlargelyintotwocamps.
Microsoft,promotingthe.NETFramework,isinone,whilemostothervendors
backingtheJavaenvironmentareintheother.Eachtechnologyhasitsfansand
detractors,andeachhasasubstantialinstalledbasetoday.
Thesecompetingworldsarestrikinglysimilar.Toseehowsimilar,comparethe
figureabovewithFigure1-1.Bothenvironmentssupportthesamekindsof
applications,andbothprovidealargestandardlibrarytohelpbuildthose
applications.TheJavalibrary,mostlyknowntodayasJava2EnterpriseEdition
(J2EEorjustJEE)includesJavaServerPages(JSP)forWebscripting,Swingfor
buildingGUIs,JAX-WS(formerlyJAX-RPC)forWebservicesbased
communication,EnterpriseJavaBeans(EJB)forbuildingscalableserver
applications,JDBCfordatabaseaccess,andotherclasses.Thesetechnologies
areanalogoustothe.NETFramework'sASP.NET,WindowsForms,ASP.NETWeb
Services,EnterpriseServices,andADO.NET,respectively.TheJavavirtual
machineisalsomuchlikethe.NETFramework'sCLR,andeventhesemanticsof

thedominantlanguagesMicrosoft'sC#andVBvs.Javaarequitesimilar.
Therearealsodifferences,ofcourse.Oneobviousdistinctionbetweenthetwois
thattheJavaenvironmentrunsondiverseoperatingsystems,whilethe.NET
FrameworkfocusesonWindows.Thetrade-offhereisclear:Portabilityisgood,
butitpreventstightintegrationwithanyonesystem,andintegrationisalso
good.Youcan'thaveeverything,atleastnotallatthesametime.Also,Javabasedproductsareavailablefrommultiplevendors,whileonlyMicrosoft
providesthe.NETFramework.DifferentJavavendorscanprovidedifferent
extensionstothecorespecifications,sodeveloperscangetsomewhatlocked
intoasinglevendor.Still,portabilityacrossdifferentJavaplatformsispossible,
whilethe.NETFrameworkunambiguouslytiesyourapplicationtoMicrosoft.
Thisbifurcationandthecompetitionitengendersareultimatelyagoodthing.


Bothcampshavehadgoodideas,andeachhasborrowedfromtheother.Having
onecompletelydominanttechnology,whetherthe.NETFrameworkorJava,
wouldproduceastultifyingmonopoly,whilehavingadozenviablechoiceswould
leadtoanarchy.Twostrongcompetitors,eachworkingtooutdotheother,isjust
right.

Applicationswritteninany.NETlanguagecanusethecodein
the.NETFrameworkclasslibrary.Amongthemostimportant
technologiesprovidedinthislibraryarethefollowing:
ASP.NET:Classesfocusedonbuildingbrowser-accessible
applications.
WindowsForms:ClassesforbuildingWindowsgraphical
userinterfaces(GUIs)inanyCLR-basedprogramming
language.
ASP.NETWebServices(alsocalledASMX):Classesfor
creatingapplicationsthatcommunicatewithother
applicationsusingWebservices.

EnterpriseServices:Classesthatprovidedistributed
transactions,objectinstancecontrol,andotherservices
usefulforbuildingreliable,scalableapplications.
ADO.NET:Classesfocusedonaccessingdatastoredin
relationaldatabasemanagementsystems(DBMS).

The.NETFrameworkclasslibraryprovidesstandardcodeforcommonfunctions


The.NETFrameworkclasslibrarycontainsmuchmorethanthis
shortlistindicates.Amongtheotherservicesitprovidesare
supportforcreatingandworkingwithXMLdocuments,avariety
ofsecurityservices,andmechanismsforinteroperatingwith
applicationsbuiltusingolderWindowstechnologiessuchasthe
ComponentObjectModel(COM).

The.NETFrameworksupportsvariouskindsofapplications

Asthisshortdescriptionsuggests,the.NETFrameworkclass
librarycanbeusedtocreatemanydifferenttypesof
applications.Andbecausealloftheservicesinthislibraryare
builtontheCLR,applicationscancombinethemasneeded.A
browserapplicationbuiltusingASP.NET,forexample,mightuse
ADO.NETtoaccessstoreddataandEnterpriseServicesto
performdistributedtransactions.

A.NETFrameworkapplicationconsistsofmanagedcode

Softwarethatusesthe.NETFramework(andthusreliesonthe
CLR)isreferredtoasmanagedcode.AsFigure1-2shows,an

applicationcanbebuiltsolelyfrommanagedcode,relying
entirelyontheCLRandtherelevantpartsofthe.NET
Frameworkclasslibrary.Anapplicationcanalsobebuiltfroma
combinationofmanagedcodeandordinaryunmanagedcode,
withthetwointeractingasnecessary.Thissecondoption,
shownontherightsideofthefigure,isespeciallyimportantfor
existingapplications.MostnewWindowsapplicationscreated
todayarebuiltwhollyinmanagedcode,butitcanalsobe


usefultoextendpre-.NETapplicationswithmanagedcode.And
althoughit'snotshowninthefigure,it'sstillpossibletocreate
newWindowsapplicationsentirelyinunmanagedcodeusingthe
.NETFrameworkisn'tobligatory.

Figure1-2.Anapplicationcanbebuiltentirely
frommanagedcodeorfromacombinationof
managedandunmanagedcode.

Managedcodeistypicallyobject-oriented,sotheobjectsit
createsandusesareknownasmanagedobjects.Amanaged
objectcanuseandinheritfromanothermanagedobjectevenif
thetwoarewrittenindifferentlanguages.Thisfactisakey
partofwhatmakesthe.NETFrameworkclasslibraryan
effectivefoundation:ObjectswritteninanyCLR-basedlanguage
caninheritandusetheclasslibrary'scode.Giventhe
fundamentalroleplayedbytheCLR,understandingthe.NET
Frameworkbeginswithunderstandingthisruntime
environment.

Managedcodeistypicallybuiltusingmanagedobjects


TheCommonLanguageRuntime
Builtfromscratchtosupportmodernapplications,theCLR
embodiesacurrentviewofwhataprogrammingenvironment
shouldbe.Whileit'shardtoclaimcompleteoriginalityforany
ideaincomputersciencetoday,itisfairtosaythatthis
essential.NETtechnologytakesaninterestingnewapproachto
programminglanguages.

WhattheCLRDefines
Thinkabouthowaprogramminglanguageistypicallydefined.
Eachlanguagecommonlyhasitsownuniquesyntax,itsownset
ofcontrolstructures,auniquesetofdatatypes,itsownnotions
ofhowclassesinheritfromoneanother,andmuchmore.The
choicesalanguagedesignermakesaredrivenbythetarget
applicationsforthelanguage,whoitsusersaremeanttobe,
andthedesigner'sownsensibilities.

There'swidespreadagreementonthefeaturesamodernprogramminglanguage
shouldoffer

Yetmostpeopleagreeonmuchofwhatamoderngeneralpurposeprogramminglanguageshouldprovide.Whileopinions
onsyntaxdiffersomedeveloperslovecurlybraces,othersabhor
themthere'swidespreadagreementonwhatsemanticsa


languageshouldoffer.Giventhis,whynotdefineastandard
implementationofthosesemantics,thenallowdifferent

syntaxestobeusedtoexpressthosesemantics?


LookingBackward:WindowsDNAandCOM
Formostofthe1990s,applicationdevelopersintheMicrosoftenvironmentrelied
onasetoftechnologiesthatbecameknownasWindowsDNA.Those
technologiesincludedtheComponentObjectModel(COM)andDistributedCOM
(DCOM),alargergroupofCOM-basedtechnologiesknowncollectivelyasCOM+,
supportforcreatingbrowserapplicationsusingActiveServerPages(ASP),data
accesssupportwithActiveXDataObjects(ADO),andothers.Themost
commonlyusedlanguagesforbuildingWindowsDNAapplicationswereVBand
C++,bothsupportedbyearlierversionsofVisualStudio.
Tensofthousandsofapplicationsbasedonthesetechnologiesareinproduction
today,providingsolidevidenceofWindowsDNA'ssuccess.Yetthetechnologies
WindowsDNAincludesweredevelopedindependentlyoveraperiodofseveral
years.Becauseofthis,theintegrationamongthemwasn'tascompleteasit
mighthavebeen.Forexample,whiletheWindowsDNAenvironmentlet
developersusevariousprogramminglanguages,eachlanguagehasitsown
runtimelibraries,itsowndatatypes,itsownapproachtobuildingGUIs,and
otherdifferences.Applicationswrittenindifferentlanguagesalsoaccessed
systemservicesindifferentways.C++applicationscouldmakedirectcallsto
theoperatingsystemthroughtheWin32interface,forinstance,whileVB
applicationstypicallyaccessedtheseservicesindirectly.Thesedifferencesmade
lifechallengingfordevelopersworkinginmorethanonelanguage.COM,by
definingcommonconventionsforinterfaces,datatypes,andotheraspectsof
interactionamongdifferentsoftware,waseffectivelytheducttapethatheldthis
complexenvironmenttogether.
Byprovidingacommonfoundationthatcanbeusedfromalllanguages,the
.NETFrameworksignificantlysimplifiedlifeforWindowsdevelopers.Applications
builtonthe.NETFrameworkdon'tfacemanyoftheproblemsthatCOM

addresses.NETFrameworkapplicationsallusetheCLR,forexample,which
definesacommonapproachtointerfacesandotherdatatypesandsotheglue
betweendifferentlanguagesthatCOMprovidesisnolongernecessary.Thisis
whyCOMtechnologyisn'tusedinbuildingpure.NETFrameworkapplications.
Instead,developerscanbuildsoftwarethatinteractsinamorenaturaland
substantiallysimplerway.
Forthemostpart,thearrivalofthe.NETFrameworkwasthedeathknellfor
WindowsDNAandCOM.It'stakenquiteawhilefororganizationstomigrateto
thenewworldof.NET,andmanyapplicationsbuiltwiththeseolderWindows
technologiesarestillinproduction.Still,withfewexceptions,seriousnew
Windowsdevelopmenttodayuses.NET,notWindowsDNA.