OReilly COM and dot NET component services sep 2001 ISBN 0596001037 pdf

COM and NET Com ponent Services Dedicat ion Foreword Preface Scope of This Book Som e Assum pt ions About t he Reader Definit ions and Text Convent ions Ot her COM+ Books and Refer ences How t o Cont act Us Acknow ledgm ent s COM+ Com ponent Serv ices 1.1 COM+ Com ponent Ser v ices 1.2 The Com ponent Ser vices Explor er 1.3 Hello COM+ 1.4 COM+ Configur ed Com ponent s 1.5 Applicat ions, DLLs, and Com ponent s 1.6 Configur ing COM+ Applicat ions 1.7 Debugging COM+ Applicat ions 1.8 Deploy ing COM+ Applicat ions 1.9 Sum m ary COM+ Cont ext 2.1 Encapsulat ion v ia Marshaling in COM 2.2 Encapsulat ion v ia I nt ercept ion in COM+ 2.3 The Cont ext Obj ect 2.4 The Call Obj ect 2.5 Cr oss- Cont ext Manual Marshaling 2.6 Sum m ary COM+ I nst ance Managem ent 3.1 Client Types 3.2 I nst ance Managem ent and Scaling 3.3 Obj ect Pooling 3.4 Just - in- Tim e Act iv at ion 3.5 Com bining JI TA w it h Obj ect Pooling 3.6 Obj ect Const r uct or St r ing 3.7 COM+ I nst ance Managem ent Pit falls COM+ Transact ions 4.1 Transact ion Basics 4.2 Transact ion Pr opert ies 4.3 Transact ion Scenarios 4.4 COM+ Transact ions Archit ect ur e 4.5 Configur ing Transact ions 4.6 Vot ing on a Transact ion 4.7 Transact ional Obj ect Life Cycle 4.8 Designing Transact ional Com ponent s 4.9 Nont ransact ional Client s 4.10 Transact ions and Obj ect Pooling 4.11 Com pensat ing Tr ansact ions 4.12 Transact ion Ex ecut ion Tim e 4.13 4.14 4.15 4.16 Tracing Transact ions I n- Doubt Transact ions Transact ion St at ist ics COM+ Transact ions Pit falls COM+ Concur r ency Model 5.1 Obj ect - Orient ed Program m ing and Mult iple Threads 5.2 Apart m ent s: The Classic COM Solut ion 5.3 Act iv it ies: The COM+ I nnovat ion 5.4 COM+ Configurat ion Set t ings 5.5 Act iv it ies and JI TA 5.6 Act iv it ies and Transact ions 5.7 Tracing Act iv it ies 5.8 The Neut ral Threaded Apart m ent 5.9 Sum m ary Pr ogram m ing t he COM+ Cat alog 6.1 Why Pr ogram t he Cat alog? 6.2 The Cat alog Progr am m ing Model 6.3 Cat alog St ruct ur e 6.4 I nt eract ing w it h t he Cat alog 6.5 Feat ur es of COMAdm inCat alog 6.6 The COM+ Cat alog and Transact ions 6.7 Sum m ary COM+ Secur it y 7.1 The Need for Secur it y 7.2 Basic Secur it y Ter m s 7.3 Role- Based Secur it y 7.4 Secur ing a Ser ver Applicat ion 7.5 Secur ing a Librar y Applicat ion 7.6 Pr ogram m at ic Role- Based Secur it y 7.7 Secur it y Boundar ies 7.8 Advanced COM+ Securit y 7.9 COM+ Secur it y Pit falls 7.10 Sum m ary COM+ Queued Com ponent s 8.1 Maj or Benefit s of Queued Com ponent s 8.2 Queued Com ponent s Archit ect ure 8.3 Com ponent Ser vices Explor er Configurat ion 8.4 I nvoking Queued Com ponent s on t he Client Side 8.5 Designing Queued Com ponent I nt erfaces 8.6 Receiv ing Out put from a Queued Com ponent 8.7 Queued Com ponent Er ror Handling 8.8 Queued Com ponent s and Transact ions 8.9 Sy nchr onous Versus Asy nchronous Com ponent s 8.10 Queued Com ponent s Secur it y 8.11 Queued Com ponent s Pit falls 8.12 Sum m ary COM+ Ev ent Serv ice 9.1 Classic COM Ev ent s 9.2 COM+ Ev ent Model 9.3 The Event Class 9.4 Subscript ion Ty pes 9.5 Deliv ering Ev ent s 9.6 Ev ent Filt er ing 9.7 Dist ribut ed COM+ Ev ent s 9.8 Asy nchronous Ev ent s 9.9 COM+ Ev ent s and Transact ions 9.10 COM+ Ev ent s and Securit y 9.11 COM+ Ev ent s Lim it at ion 9.12 Sum m ary 10 .NET Serv iced Com ponent s 10.1 Developing Serv iced Com ponent s 10.2 NET Assem blies and COM+ Applicat ions 10.3 Regist er ing Assem blies 10.4 Configur ing Ser v iced Com ponent s 10.5 Applicat ion Act iv at ion Type 10.6 The Descr ipt ion At t r ibut e 10.7 Accessing t he COM+ Cont ext 10.8 COM+ Cont ext At t ribut es 10.9 COM+ Obj ect Pooling 10.10 COM+ Just - in- Tim e Act ivat ion 10.11 COM+ Const r uct or St r ing 10.12 COM+ Transact ions 10.13 COM+ Sy nchronizat ion 10.14 Pr ogram m ing t he COM+ Cat alog 10.15 COM+ Secur it y 10.16 COM+ Queued Com ponent s 10.17 COM+ Loosely Coupled Ev ent s 10.18 Sum m ary A The COM+ Logbook A.1 Logbook Requirem ent s A.2 Log File Exam ple A.3 Using t he Logbook A.4 Configur ing t he Logbook A.5 How Does t he Logbook Work? A.6 Sum m ary B COM+ 1.5 B.1 I m prov ed User I nt erface Usabilit y B.2 Legacy Applicat ions and Com ponent s B.3 Disabling Applicat ions and Com ponent s B.4 Pausing Applicat ions B.5 Serv ice Act iv at ion Type B.6 I m prov ed Queuing Support B.7 Applicat ion Pooling and Recycling B.8 Applicat ion Dum p B.9 Applicat ion Part it ioning B.10 Aliasing Com ponent s B.11 Configurable Transact ion I solat ion Level B.12 I m prov ed Cont ext Act ivat ion Set t ing B.13 Pr ivat e Com ponent s B.14 Web Serv ices in COM+ 1.5 B.15 Sum m ary C I nt r oduct ion t o NET C.1 NET Program m ing Languages C.2 Packaging NET Com ponent s: Assem blies C.3 Dev eloping NET Com ponent s C.4 Wr it ing NET Client - Side Code C.5 NET as a Com ponent Technology C.6 Com posing Assem blies Colophon D e dica t ion To m y wife, Dana For e w or d I fir st ran int o COM+ back in 1996 I n t hose days, I was w ork ing as a Com m on Obj ect Request Br oker Ar chit ect ure ( CORBA) consult ant and was fr esh out of I BM, wher e I had been heav ily inv olved in I BM’s or iginal CORBA im plem ent at ion CORBA was t he first of t he ar chit ect ures t hat we m ight describe t oday as Dist ribut ed Com ponent ar chit ect ures, which set t he st age for bot h COM/ DCOM in t he Microsoft space and RMI / I I OP in t he Java space Back t hen, I was int er est ed in a part icularly k not t y problem relat ed t o dist ribut ed com ponent archit ect ur es Syst em s built w it h such archit ect ures had a charact er ist ic perform ance pat t ern They could handle large num ber s of t r ansact ions, as long as t hose t ransact ions originat ed from a sm all num ber of client s So, for ex am ple, 5,000 t r ansact ions per m inut e div ided bet ween client s wor ked fine But when t hose sam e 5,000 t r ansact ions per m inut e wer e split am ong 1,000 client s, each pr ocessing t ransact ions per m inut e, t he sy st em s chok ed This was odd, I t hought Why should client s, each processing 1,000 t ransact ions per m inut e, be fundam ent ally different t han 1,000 client s, each pr ocessing t ransact ions per m inut e? What is t he difference bet ween t he first 5,000 t r ansact ions per m inut e and t he second? Dist ribut ed com ponent archit ect ures, as t hey ex ist ed in 1996, dict at ed a one- t o- one relat ionship bet ween client s and com ponent inst ances The business logic of such archit ect ur es is in t he com ponent inst ances And it is t he business logic t hat m ak es t r ansact ional request s of t r ansact ional r esources, such as t he dat abase I n order t o m ake t r ansact ional request s, t he com ponent inst ances r equire expensive r esources, such as dat abase connect ions We run out of st eam ( i.e., t r ansact ional t hroughput ) when one of t wo t hings happen: we over load t he syst em w it h t r ansact ional request s or we run out of resources ( e.g., dat abase connect ions) Clearly , going from client s, each m ak ing 1,000 t ransact ional request s per m inut e, t o 1,000 client s, each m ak ing t r ansact ional request s per m inut e, has no over all im pact on t he t ransact ional t hr oughput Therefore, t he r eason why our dist ribut ed com ponent sy st em s m ust be dying is t hat we ar e running out of resour ces So t he answer t o get t ing lot s of client s on a dist r ibut ed com ponent archit ect ure is not going t o com e fr om increased capabilit y of t he back- end t r ansact ional resources ( e.g., dat abases) I t will have t o com e fr om som et hing else- som et hing t hat allows r esour ce shar ing This, t hen, is t he problem I wor ked on back in 1996 How y ou get several client s t o share resources in a dist r ibut ed com ponent archit ect ure? The solut ion t o t his problem cam e fr om an unex pect ed source I was asked t o writ e a book on COM and DCOM I knew very lit t le about COM and DCOM back t hen As I look ed over t he COM/ DCOM whit e paper s on t he Microsoft web sit e, I quickly recognized it as a t y pical dist ribut ed com ponent archit ect ure and predict ed t he sam e t hr oughput problem s I had seen in ot her dist r ibut ed com ponent sy st em s As I browsed t hrough t he whit e paper s, I not iced an obscure bet a product called Micr osoft Transact ion Serv er ( MTS) At first , I dism issed MTS as an API used t o m anage dist ribut ed t ransact ions But as I read m ore about MTS, I r ealized t hat it had lit t le t o wit h t r ansact ions I nst ead, it at t ack ed a m uch m or e int erest ing problem : how t o shar e r esources am ong client s I n a nut shell, MTS addr essed t he very problem t hat had so v exed t he exist ing dist ribut ed com ponent syst em s- how t o support a large num ber of lowt r ansact ion generat ing client s! I did event ually w rit e t hat book, as well as m any ar t icles on t he im port ance of t he ideas int r oduced by MTS Many of t hese ar t icles appear ed in m y Obj ect Wat ch newslet t er ( available at www.obj ect wat ch.com ) , a newslet t er t hat has, ov er t im e, becom e influent ial in it s space Back in 1996, I predict ed t hat MTS would be a hist or ically im port ant product - one t hat w ould redefine approaches t o scalabilit y in dist ribut ed com ponent sy st em s I n fact , t hat predict ion has com e t r ue Today , every infrast r uct ure designed t o suppor t high scalabilit y in dist r ibut ed com ponent syst em s is based dir ect ly on t he ideas, algorit hm s, and pr incipals first int roduced by MTS in 1996 Ent erprise Jav aBeans, for exam ple, t he Jav a scalabilit y infrast r uct ure, is alm ost a direct copy of MTS But w hat does t his have t o wit h COM+ , you m ay ask I t t urns out t hat COM+ and MTS are one and t he sam e Microsoft , never know n for it s m arket ing savvy , decided t o wait unt il cust om ers finally got used t o t he nam e MTS ( it self a m isleading nam e) , and t hen it pulled a fast one- it swit ched t he nam e! And not j ust any nam e, but one t hat would be as confusing as possible! So t hey renam ed MTS as COM+ Nat urally, cust om ers assum ed t hat COM+ was t he next release of COM I n fact , COM+ was t he next release of MTS Now Microsoft has announced NET Once again, t he br illiant Microsoft m ark et ing organizat ion has left m any cust om er s confused I s COM+ now dead? Far fr om it —.NET is a series of int er est ing new feat ur es, none of which r eplace COM+ COM+ is st ill t he scalable infrast r uct ure t hat suppor t s resour ce shar ing and deals w it h t he m yr iad of issues ( such as securit y and t r ansact ion boundar y m anagem ent ) t hat ar e so closely relat ed t o r esource sharing and so cr ucial t o dist ribut ed applicat ions So whet her you ar e rushing int o Micr osoft ’s new NET t echnology plat for m or t aking a wait and see at t it ude, if y ou need t o put a lot of client s around your sy st em , y ou need t o under st and COM+ Ther efore, t his book is very t im ely COM+ is going t o be wit h us for a long t im e I t s nam e m ay change again, j ust t o confuse t he innocent ; but t he ideas, algor it hm s, and principals will not COM+ , under what ever nam e, is here t o st ay ! Roger Sessions, CEO, Obj ect Wat ch, I nc Publisher, Obj ect Wat ch newslet t er ( www.obj ect wat ch.com ) Aut hor, COM+ and t he Bat t le for t he Middle Tier Aust in, Tex as Pr e fa ce This book discusses COM+ com ponent services Each service is covered in it s own chapt er , and each chapt er discusses a sim ilar range of issues: t he pr oblem t he serv ice addr esses, possible solut ions t o t hat problem , an in- dept h descript ion of t he COM+ solut ion, t r adeoffs, design, and im plem ent at ion guidelines, t ips, and know n pit falls I have t ried t o prov ide useful design inform at ion and lessons I learned while applying COM+ I also descr ibe COM+ helper classes and ut ilit ies I developed t hat will enhance your pr oduct ivit y significant ly ( The COM+ Event s helper obj ect s and t he COM+ Logbook are prim e ex am ples.) This book focuses on t he " how t o" — t hat is, it pr ov ides pract ical inform at ion You should read t he chapt er s in or der , since m ost chapt ers r ely on inform at ion discussed in t he pr eceding chapt er s The book also aim s t o ex plain COM+ st ep by st ep A soft ware engineer alr eady fam iliar wit h COM who want s t o k now what COM+ is and how t o use it can read t his book and st ar t developing COM+ applicat ions im m ediat ely Scope of Th is Book Her e is a brief sum m ary of t he chapt ers and appendixes in t his book: • • • Chapt er int roduces t he Com ponent Serv ices Ex plorer and basic COM+ t er m inology This chapt er deliberat ely holds your hand as you develop your fir st " Hello World" COM+ com ponent Subsequent chapt ers m uch less handholding and assum e y ou ar e fam iliar w it h t he COM+ env ir onm ent I f you alr eady have experience w it h basic COM+ developm ent, feel fr ee t o sk ip t his chapt er Chapt er dem yst ifies t he COM+ cont ext by present ing it as t he key m echanism for providing com ponent services using call int ercept ion Generally , y ou need not be concerned wit h cont ext s at all How ever, t he COM+ cont ext underlies t he way COM+ serv ices are im plem ent ed Chapt er describes t wo scalabilit y - enabling m echanism s t hat COM+ provides for a m odern ent erprise applicat ion: obj ect pooling and Just - in- Tim e Act iv at ion ( JI TA) The discussion of inst ance m anagem ent , and especially JI TA, is independent of t r ansact ions Ear ly COM+ docum ent at ion and books t ended t o couple inst ance m anagem ent and t r ansact ions How ever, I found t hat not only can you use inst ance m anagem ent independent ly of t ransact ions, but it is easier t o explain it t hat 10 ... ledgm ent s COM+ Com ponent Serv ices 1.1 COM+ Com ponent Ser v ices 1.2 The Com ponent Ser vices Explor er 1.3 Hello COM+ 1.4 COM+ Configur ed Com ponent s 1.5 Applicat ions, DLLs, and Com ponent... debug, and deploy a sim ple COM+ " Hello Wor ld" applicat ion, using a t r adit ional COM com ponent and learning about COM+ applicat ion t y pes and configured com ponent s as y ou so 17 1 COM+ Com. .. public I nt ernet Collect ively, t he services t hat support COM and NET com ponent based applicat ions ar e known as t he COM+ com ponent ser vices, or sim ply as COM+ The Evolut ion of COM + Se