Creating a Service Platform for.net. Clement Escoffier PhD Student University of Grenoble

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2 Creating a Service Platform for.net Clement Escoffier PhD Student University of Grenoble

3 LSR-IMAG : Logiciels, Systèmes & Réseaux LSR : Software, Systems & Networks IMAG federation Member of the ObjectWeb consortium

4 ObjectWeb ObjectWeb Open Source Middleware Consortium Non-profit, open, business neutral Industry-grade projects Compliance with open standards

5 Context OSGi specifications are Java-centric Microsoft.NET Virtual Machine Well known Already deployed with Windows XP Able to load and to unload dynamic code Why not implement OSGi R3 specifications on.net?

6 Outline.NET overview Goals of OSGi.NET Issues & alternative approaches Conclusion & perspectives

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

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

9 .NET Framework Overview : Assembly Assemblies : Set of classes, resources and metadata Support of version Possibility to sign an assembly Unit of packaging & deployment Unit of loading

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

11 .NET Framework Overview : Java vs.net Virtual Machine Languages Internal language Deployment Unit Load unit Unload Unit Java JVM Java (supported by Sun) Byte code Classes, JAR Classes Classes (Garbage Collector).NET CLR C# (ECMA & ISO) J#, VB.NET MSIL Assemblies Assemblies Application domain

12 OSGi.NET : Goals Implement OSGi specification on.net Mail Service Mail with Temp Temperature HTTP Server OSGi.NET Video on the Web Camera Service Invocation Code Sharing Dynamic Code Loading Service arrival and departure Common Language Runtime Dynamic Code Unloading Operating System

13 Key Technical Differences Technical differences between.net and Java Class loading flexibility Loading / Unloading system Code sharing No direct way to map OSGi features onto.net

14 Alternative Implementation Approaches Four alternative approaches Mono-application domain Multi-application domains Hybrid alternative CLR modification

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

16 Mono-Application Domain Service invocation.. Ok Service arrival & departure..... Ok Dynamic loading. Ok Code sharing... No All loaded code is shared inside an application domain Does not support private code Dynamic unloading. No

17 Multi-Application Domain 1 bundle inside 1 application domain OSGi.NET in one application domain, bundles reside in their own application domains.net Remoting AppDomain 1 AppDomain 2 AppDomain 3 Provider Contract Requester Contract Contract AppDomain 0 : OSGi.NET Registry Loader Common Language Runtime Operating System

18 Multi-Application Domain Service invocation Ok/No Service invocation must use.net Remoting Significant overhead Service arrival & departure... Ok Dynamic loading. Ok Not fully transparent Code sharing... No All code is private Dynamic unloading. Ok

19 Hybrid Solution Mix the 2 previous solutions Different services set inside application domain Allow bindings inside & outside application domain Different range of services (local / remote services) Several registries (local and global) Trade off for application designer How to group services into application domains Hypothesized, but not implemented

20 Hybrid Solution AppDomain 1 Local Provider Registry Remote Provider AppDomain 2 Registry Requester Contract2 Contract1 Contract2 AppDomain 0 : OSGi.NET Global Registry Loader Common Language Runtime Operating System

21 The Hybrid Solution Service invocation.....ok Choice between local service & remote service Service apparition & departure ok Dynamic loading Ok Code sharing.....no Inside application domain, all code is shared Outside application domain, no code sharing Dynamic unloading Ok Unload an application domain = unload a set of services

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

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

24 CLR Modification Service Invocation....Ok Service apparition & departure.ok Dynamic Loading Ok Code sharing......ok Dynamic Unloading Ok But it s s no longer standard.net and was too complex to implement within our time constraints

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

26 Conclusion.NET Well-known virtual machine Distributed with Windows XP OSGi technology is Java-centric Tried to implement OSGi on.net => OSGi.Net Four alternatives Is any alternative fully compliant with OSGi specification? No

27 Perspectives OSGi Release 4 More difficult (more sophisticated class sharing & management) Waiting the next release of the.net Framework 2007?? Not yet clear : Unloading assemblies individually.net Remoting optimizations

28 Questions???

29 ROTOR Shared Source CLI : Distributed by Microsoft Very close with the official framework Contains VM, Compilers Some numbers 1.9 millions of LOC (C++, C#, MSIL, Assembler) 5900 sources files, 9700 files Kernel (mscorlib( mscorlib) ) : 867 classes in C++ Discussions With the DOTNET-ROTOR mailing list Microsoft newsgroups

30 Multi-Domain Approach : Benchmark Method invocation time Time Temps in en ms Calls intra-application application domain vs Calls inter-application domain Processor 1 Ghz,, RAM 768 Mo, Windows XP SP2, CLR Intra Domain Calls Temps des appels locaux Void Small Object Medium Object Huge Object Temps en Time in ms Inter Domains Calls Appel locaux via.net Remoting Void Small Object Medium Object Huge Object