OSGi World Congress 2005 - Developer Forum Day 2

2. Creating a Service
Platform for .NET
Clement EscoffierClement Escoffier –– PhD StudentPhD Student
University ofUniversity of GrenobleGrenoble

3. LSRLSR--IMAG :IMAG : LogicielsLogiciels,, SystSystèèmesmes && RRééseauxseaux
•• LSR :LSR :
–– Software, Systems & NetworksSoftware, Systems & Networks
–– IMAG federationIMAG federation
–– Member of theMember of the ObjectObjectWebWeb consortiumconsortium

4. ObjectObjectWebWeb
•• ObjectObjectWebWeb
–– Open Source MiddlewareOpen Source Middleware
–– ConsortiumConsortium
•• NonNon--profit, open, business neutralprofit, open, business neutral
•• IndustryIndustry--grade projectsgrade projects
•• Compliance with open standardsCompliance with open standards

5. ContextContext
•• OSGi specifications areOSGi specifications are JavaJava--centriccentric
•• Microsoft .NETMicrosoft .NET
–– Virtual MachineVirtual Machine
–– Well knownWell known
–– Already deployed with Windows XPAlready deployed with Windows XP
–– Able to load and to unload dynamic codeAble to load and to unload dynamic code
•• Why not implement OSGi R3 specifications onWhy not implement OSGi R3 specifications on
.NET ?.NET ?

6. OutlineOutline
•• .NET overview.NET overview
•• Goals ofGoals of OSGi.NETOSGi.NET
•• Issues & alternative approachesIssues & alternative approaches
•• Conclusion & perspectivesConclusion & perspectives

7. Microsoft .NETMicrosoft .NET
•• .NET initiative announced in July 2000 by Microsoft.NET initiative announced in July 2000 by Microsoft
–– COM+, ASP, XML, SOAP, WSDL, UDDICOM+, ASP, XML, SOAP, WSDL, UDDI
–– Microsoft .NET, Mono, Shared Source CLI, Compact .NETMicrosoft .NET, Mono, Shared Source CLI, Compact .NET
•• .NET Goals :.NET Goals :
–– Distributed computing and mainly InternetDistributed computing and mainly Internet
–– ComponentizationComponentization
–– Enterprise servicesEnterprise services
Operating System
.NET
Enterprise
Servers
.NET
Framework
.NET
Building
Block Services
Exchange
Server;
SQL Server
…
Microsoft
Passport,
…
Microsoft Visual Studio .NET

8. .NET Framework Overview.NET Framework Overview
•• CLR : Common Language RuntimeCLR : Common Language Runtime
–– Support of several languages (C#, J#,Support of several languages (C#, J#, Cobol.NETCobol.NET))
–– Interpretation of MSIL CodeInterpretation of MSIL Code
Operating System
Common Language Runtime
(debug, exception, JIT …)
Framework Base Classes
Data & XML classes
Web
Services
Web
Forms
Win
Forms
Framework

9. .NET Framework Overview : Assembly.NET Framework Overview : Assembly
•• Assemblies :Assemblies :
–– Set of classes, resources and metadataSet of classes, resources and metadata
–– Support of versionSupport of version
–– Possibility to sign an assemblyPossibility to sign an assembly
–– Unit of packaging & deploymentUnit of packaging & deployment
–– Unit of loadingUnit of loading

10. .NET Framework Overview : Application Domain.NET Framework Overview : Application Domain
•• Application Domain (Application Domain (AppdomainAppdomain))
–– Isolated Execution EnvironmentIsolated Execution Environment
•• An application runs in an application domainAn application runs in an application domain
•• Several application domains in one CLRSeveral application domains in one CLR
•• Virtual processVirtual process
–– Assemblies are loaded inside application domainAssemblies are loaded inside application domain
–– Unloading unitUnloading unit
Common Language Runtime
AppDomain1 AppDomain2
ASM 1 ASM 2
ASM1.dll
ASM2.dll
ASM3.dllASM 3

11. .NET Framework Overview : Java.NET Framework Overview : Java vsvs .NET.NET
JavaJava .NET.NET
Virtual MachineVirtual Machine JVMJVM CLRCLR
LanguagesLanguages
JavaJava
(supported by Sun)(supported by Sun)
C# (ECMA & ISO)C# (ECMA & ISO)
J#, VB.NETJ#, VB.NET ……
Internal languageInternal language Byte codeByte code MSILMSIL
Deployment UnitDeployment Unit Classes, JARClasses, JAR AssembliesAssemblies
Load unitLoad unit ClassesClasses AssembliesAssemblies
Unload UnitUnload Unit
Classes (GarbageClasses (Garbage
Collector)Collector)
Application domainApplication domain

12. OSGi.NETOSGi.NET : Goals: Goals
•• Implement OSGi specification on .NETImplement OSGi specification on .NET
MailService
MailwithTemp
Temperature
HTTPServer
VideoontheWeb
Camera
•• Service InvocationService Invocation
•• Dynamic Code LoadingDynamic Code Loading
•• Dynamic Code UnloadingDynamic Code Unloading
•• Code SharingCode Sharing
Operating System
Common Language Runtime
OSGi.NET
•• Service arrivalService arrival
and departureand departure

13. Key Technical DifferencesKey Technical Differences
•• Technical differences between .NET and JavaTechnical differences between .NET and Java
–– Class loading flexibilityClass loading flexibility
–– Loading / Unloading systemLoading / Unloading system
–– Code sharingCode sharing
•• No direct way to map OSGi features onto .NETNo direct way to map OSGi features onto .NET

14. Alternative Implementation ApproachesAlternative Implementation Approaches
•• Four alternative approachesFour alternative approaches
–– MonoMono--application domainapplication domain
–– MultiMulti--application domainsapplication domains
–– Hybrid alternativeHybrid alternative
–– CLR modificationCLR modification

15. MonoMono--application domainapplication domain
•• 1 Bundle = 1 Assembly1 Bundle = 1 Assembly
•• 1 Application domain for1 Application domain for OSGi.NETOSGi.NET & Services& Services
Operating System
Common Language Runtime
ASM 1 :
Provider
Loader
Application domain
ASM 2 :
Requester
ASM 3 :
Contract
Registry

16. MonoMono--Application DomainApplication Domain
•• Service invocationService invocation ………………………………………………………….... OkOk
•• Service arrival & departureService arrival & departure …………....………………………….. OkOk
•• Dynamic loadingDynamic loading ……………………..………………………………………… OkOk
•• Code sharingCode sharing ……………………………………………………………………...... NoNo
–– All loaded code is shared inside an application domainAll loaded code is shared inside an application domain
–– Does not support private codeDoes not support private code
•• Dynamic unloadingDynamic unloading ………………………………………………………….. NoNo

17. MultiMulti--Application DomainApplication Domain
•• 1 bundle inside 1 application domain1 bundle inside 1 application domain
•• OSGi.NETOSGi.NET in one application domain, bundlesin one application domain, bundles
reside in their own application domainsreside in their own application domains
.NET Remoting
Operating System
Common Language Runtime
AppDomain 1
AppDomain 0 : OSGi.NET
Provider
AppDomain 3
Contract
AppDomain 2
Requester
ContractContract
LoaderRegistry

18. MultiMulti--Application DomainApplication Domain
•• Service invocationService invocation ………………………………………………………… Ok/NoOk/No
–– Service invocation must use .NETService invocation must use .NET RemotingRemoting
–– Significant overheadSignificant overhead
•• Service arrival & departureService arrival & departure ……....……………………………….. OkOk
•• Dynamic loadingDynamic loading …………..…………………………………………………… OkOk
–– Not fully transparentNot fully transparent
•• Code sharingCode sharing ……………………………………………………………………...... NoNo
–– All code is privateAll code is private
•• Dynamic unloadingDynamic unloading ………………………………………………………….. OkOk

19. Hybrid SolutionHybrid Solution
•• Mix the 2 previous solutionsMix the 2 previous solutions
–– Different services set inside application domainDifferent services set inside application domain
–– Allow bindings inside & outside application domainAllow bindings inside & outside application domain
–– Different range of services (local /Different range of services (local / ““remoteremote”” services)services)
–– Several registries (local and global)Several registries (local and global)
•• Trade off for application designerTrade off for application designer
–– How to group services into application domainsHow to group services into application domains
•• Hypothesized, but not implementedHypothesized, but not implemented

20. Hybrid SolutionHybrid Solution
AppDomain 2
Operating System
Common Language Runtime
AppDomain 1
AppDomain 0 : OSGi.NET
Remote Provider Requester
Contract2Contract1
LoaderGlobal Registry
Local Provider
Registry
Contract2
Registry

21. The Hybrid SolutionThe Hybrid Solution
•• Service invocationService invocation …………………………………………………………………………..……....OkOk
–– Choice between local service & remote serviceChoice between local service & remote service
•• Service apparition & departureService apparition & departure …………………………………………..……........OkOk
•• Dynamic loadingDynamic loading ……………………………………………………………………....……......……OkOk
•• Code sharingCode sharing ……………………………………………………………………………………..……....NoNo
–– Inside application domain, all code is sharedInside application domain, all code is shared
–– Outside application domain, no code sharingOutside application domain, no code sharing
•• Dynamic unloadingDynamic unloading ………………………………………………………………..……......……OkOk
–– Unload an application domain = unload a set ofUnload an application domain = unload a set of
servicesservices

22. CLR ModificationCLR Modification
•• Introspection of an application domainIntrospection of an application domain
Operating System
Common Language Runtime
ASM1
Application domain
Stub Heap
Low
Frequency
Heap
High
Frequency
Heap
CL
.NET
Object1
.NET
Object1
.NET
Object2
.NET
Object2
Class 2
Set and look in
the LFP
Set and look
in the same memory
ASM2
Class 1
CL
Class 1Class 1
Class 2Class 2

23. CLR Modification in ROTORCLR Modification in ROTOR
•• The approach :The approach :
–– modification of the internal class loadermodification of the internal class loader
•• Enable private code sharingEnable private code sharing
–– Add a garbage collectorAdd a garbage collector
•• Enable unloadingEnable unloading
Operating System
Common Language Runtime
Requester
Application domain
Stub Heap
Low
Frequency
Heap
High
Frequency
Heap CL
Provider
CL
.NET
Object1
.NET
Object1
.NET
Object2
.NET
Object2
Requester-1
Contract-1
LoaderRegistry
Contract
CL
Provider-1

24. CLR ModificationCLR Modification
•• Service InvocationService Invocation …………………………………………………………....OkOk
•• Service apparition & departureService apparition & departure ………………………………..OkOk
•• Dynamic LoadingDynamic Loading ………………………………………………………………OkOk
•• Code sharingCode sharing ……………………………………………………………………......OkOk
•• Dynamic UnloadingDynamic Unloading …………………………………………………………OkOk
•• But itBut it’’s no longer standard .NET and was toos no longer standard .NET and was too
complex to implement within our time constraintscomplex to implement within our time constraints

25. Alternatives SummaryAlternatives Summary
1 2 3 4
Hybrid
solution
CLR
Modification
ROTOR with
a lot of
modifications
Standard
CLR
Reference
Mono
application
domain
Multi
Application
Domains
OSGi
Dynamism of
services
Dynamic
code loading
Dynamic
code
unloading
Direct
Invocation
Virtual
Machine
Standard
CLR
Standard
CLR
Standard
JVM
(>= 1.1)

26. ConclusionConclusion
•• .NET.NET
–– WellWell--known virtual machineknown virtual machine
–– Distributed with Windows XPDistributed with Windows XP
•• OSGi technology is JavaOSGi technology is Java--centriccentric
•• Tried to implement OSGi on .NET =>Tried to implement OSGi on .NET => OSGi.NetOSGi.Net
–– Four alternativesFour alternatives
•• Is any alternative fully compliant with OSGiIs any alternative fully compliant with OSGi
specification ?specification ?
–– NoNo

27. PerspectivesPerspectives
•• OSGi Release 4OSGi Release 4
–– More difficult (more sophisticated class sharing &More difficult (more sophisticated class sharing &
management)management)
•• Waiting the next release of the .NET FrameworkWaiting the next release of the .NET Framework
–– 2007 ??2007 ??
–– Not yet clear :Not yet clear :
•• Unloading assemblies individuallyUnloading assemblies individually
•• .NET.NET RemotingRemoting optimizationsoptimizations

28. Questions ???Questions ???

29. ROTORROTOR
•• Shared Source CLI :Shared Source CLI :
–– Distributed by MicrosoftDistributed by Microsoft
–– Very close with the official frameworkVery close with the official framework
–– Contains VM, CompilersContains VM, Compilers ……
•• Some numbersSome numbers
–– 1.9 millions of LOC (C++, C#, MSIL, Assembler)1.9 millions of LOC (C++, C#, MSIL, Assembler)
–– 5900 sources files, 9700 files5900 sources files, 9700 files
–– Kernel (Kernel (mscorlibmscorlib) : 867 classes in C++) : 867 classes in C++
•• DiscussionsDiscussions
–– With the DOTNETWith the DOTNET--ROTOR mailing listROTOR mailing list
–– Microsoft newsgroupsMicrosoft newsgroups

30. MultiMulti--Domain Approach : BenchmarkDomain Approach : Benchmark
•• Method invocation timeMethod invocation time
–– Calls intraCalls intra--application domainapplication domain vsvs Calls interCalls inter--applicationapplication
domaindomain
–– Processor 1Processor 1 GhzGhz, RAM 768 Mo, Windows XP SP2,, RAM 768 Mo, Windows XP SP2,
CLR 1.1CLR 1.1
Void Small Object Medium Object Huge Object
0
20
40
60
80
100
120
140
160
180
Temps des appels locaux
Tempsenms
Void Small Object Medium
Object
Huge Object
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
Appel locaux via .Net Remoting
Tempsenms
Intra Domain Calls Inter Domains Calls
Timeinms
Timeinms