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Universal Declarative Services
 

Universal Declarative Services

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Slides for my talk at the OSGi Community Event / Eclipse Con Europe 2012.

Slides for my talk at the OSGi Community Event / Eclipse Con Europe 2012.

See http://www.eclipsecon.org/europe2012/sessions/universal-declarative-services for abstract.

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    Universal Declarative Services Universal Declarative Services Presentation Transcript

    • Motivation Implementation Going Universal Summary Universal Declarative ServicesA component framework for C++ and a model-driven solution to polyglot components Simon Chemouil 1 1 Global Vision Systems OSGi Community Event, 2012 Simon Chemouil Universal Declarative Services
    • Motivation Implementation Going Universal SummaryWho am I? Free Software enthusiast, functional programmer, interested in model-driven development, modularity, re-usability, maintainability. . . How to never have to write that piece of software again? Technical Architect at Global Vision Systems, Toulouse We create data visualization software for large industries (2D, 3D, tables, etc). We do both Java and C++ Java using OSGi (Felix, iPojo) for server and client side (Eclipse RCP and Android) C++ to keep a fast 3D engine-agnostic manipulation layer Simon Chemouil Universal Declarative Services
    • Motivation Implementation Going Universal SummaryOutline 1 Motivation The case for modularity Service Components and C++ 2 Implementing Declarative Services for C++ Challenges in C++ Dening components 3 Going Universal Simpler Component Denitions Whats next? 4 Summary Conclusion Simon Chemouil Universal Declarative Services
    • Motivation Implementation Why modularity? Going Universal Service Components SummaryNative OSGi Did you miss Native-OSGi, Modular Software Development in a Native world by Alexander Broekhuis and Sascha Zelzer? Universal OSGi an RFP and a blog post by Peter Kriens in 2007. Apply OSGi techniques to native (C/C++) development. Simon Chemouil Universal Declarative Services
    • Motivation Implementation Why modularity? Going Universal Service Components SummaryAn OSGi Architect Walks in a C++ Bar... Our C++ project going through re-architecture / refactoring Custom-made plugin system, limited. Plugins cant use each other C/C++ OSGi ports: Celix (Alexander), CppMicroServices (Sascha), SOF, CTK, nOSGi, . . . Yet no service component framework such as Declarative Services Simon Chemouil Universal Declarative Services
    • Motivation Implementation Why modularity? Going Universal Service Components SummaryWhy a Service Component Framework? Services: powerful primitives, unpractical programming: Lack of structure Dynamic Service Components: Structure the services A nice semantic model to reason about dynamism Why is there no such framework for an OSGi C++ port: 1 Technical challenges 2 It was just not done yet! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Why modularity? Going Universal Service Components SummaryWhy Declarative Services? Many existing component frameworks for C++ Just as there were some for Java before DS No modularity Simple and matured component model A few years of personal experience Works with POJOs (or POCOs!) Components do not depend on the framework Makes them testable and easily reusable! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Why modularity? Going Universal Service Components SummaryDoes it make sense for C++? We use C++ for performance: Performance hit with component frameworks? We need extensibility and customization... Do we need modularity? Why use dierent architecture between Java and C++? What if we could talk about components, whatever the implementation language? Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryGetting started Native OSGi implementation: CppMicroServices is light, works with any shared library Inspired by PojoSR For C++! Bundles are called Modules: Native shared libraries: not archives. Moving to NativeOSGi later? Easy! Components are framework-agnostic! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryIngredients in Declarative Services Components are described in XML les in the bundle Service callbacks Dened in description Service arrival/departure Policy, Cardinality, Target Component callbacks Activation, modication, deactivation Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryComponent Descriptions in C++ XML descriptions. . . We have native shared libraries, not JARs! Instead, we register a ComponentDescriptor instance to the ComponentManager service. The ComponentManager service is provided by the core Ds4Cpp framework. Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryComponent Descriptions in C++ Denition class ComponentDescriptor { public : const s t r i n g c o m p o n e n t I d ; const s t r i n g i m p l S h a r e d O b j e c t ; const v e c t o r < s t r i n g >∗ p r o v i d e d S e r v i c e s ; v e c t o r <C o m p o n e n t R e f e r e n c e >∗ references ; const bool immediate ; const bool autoEnable ; } ; Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryComponent Descriptions in C++ Lets see how it looks like in practice. . . Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryExtensible Hello World! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryComponent Descriptions in C++ Denition s t d : : v e c t o r <ComponentReference >∗ r e f e r e n c e s = . . . ; r e f e r e n c e s −>push_back ( ComponentReference ( " greetdemo : : G r e e t P r o v i d e r " , " greetdemo : : G r e e t P r o v i d e r " , s t d : : s t r i n g ( ) , ComponentReference : : DYNAMIC, ComponentReference : : MULTIPLE , ComponentReference : : OPTIONAL_REF) ) ; s t d : : v e c t o r <s t d : : s t r i n g > s e r v i c e s ; s e r v i c e s . push_back ( " greetdemo : : GreetManager " ) ; C o m p o n e n t D e s c r i p t o r ∗ componentDesc = new ds4cpp : : C o m p o n e n t D e s c r i p t o r ( " greetdemo : : G r e e t M a n a g e r I m p l " , "" , s e r v i c e s , ∗ r e f e r e n c e s , true , true ) ; Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryA Component in C++ Denition c l a s s G r e e t M a n a g e r I m p l : p u b l i c GreetManager { public : G r e e t M a n a g e r I m p l ( ) ; v i r t u a l ~G r e e t M a n a g e r I m p l ( ) ; void activate () ; void a d d G r e e t P r o v i d e r ( G r e e t P r o v i d e r ∗) ; void removeGreetProvider ( G r e e t P r o v i d e r ∗) ; // Service methods . s t r i n g g e t D e f a u l t T a r g e t ( c o n s t s t r i n g &) c o n s t ; s t r i n g g e t G r e e t i n g ( c o n s t s t r i n g &, c o n s t s t r i n g &) const ; l i s t <s t r i n g > g e t A l l G r e e t i n g s ( c o n s t s t r i n g &) c o n s t ; l i s t <s t r i n g > g e t A v a i l a b l e L a n g u a g e s ( ) c o n s t ; }; Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryService Callbacks in C++ (1/2) No reection/introspection! There are some limited libraries (e.g Reex). C++ name mangling We cant guess the binary name Instead, we force a convention in the C++ component: set<RefName>, unset<RefName> for single dependencies add<RefName>, remove<RefName> for multiple dependencies Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryService Callbacks in C++ (2/2) Our tools: dlopen/dlsym/dlclose (and Windows equivalents) Against us: C++ name mangling Solutions? Reection libraries: too limited, not dynamic. C++11 attributes (≈ Java annotations): still largely unsupported Qt meta-objects? Not bad! Yet need a custom preprocessor Still not modular (work in progress) How about C wrappers? Dicult to write manually, but provide universal ABI! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryC Wrapper Denition e x t e r n "C" { DS_ABI_EXPORT GreetManagerImplWrapper ∗ __greetdemo__GreetManagerImpl__create ( ) { r e t u r n new GreetManagerImplWrapper ; } DS_ABI_EXPORT void __greetdemo__GreetManagerImpl__activate ( GreetManagerImplWrapper ∗ o b j e c t ) { o b j e c t −> a c t i v a t e ( ) ; } DS_ABI_EXPORT void __greetdemo__GreetManagerImpl__add_greetdemo__GreetProvider ( GreetManagerImplWrapper ∗ o b j e c t , : : us : : Base ∗ s e r v i c e ) { greetdemo : : G r e e t P r o v i d e r ∗ l s e r v i c e = dynamic_cast <greetdemo : : G r e e t P r o v i d e r ∗ >( s e r v i c e ) ; o b j e c t −>a d d G r e e t P r o v i d e r ( l s e r v i c e ) ; } DS_ABI_EXPORT void __greetdemo__GreetManagerImpl__remove_greetdemo__GreetProvider ( GreetManagerImplWrapper ∗ o b j e c t , : : us : : Base ∗ s e r v i c e ) { greetdemo : : G r e e t P r o v i d e r ∗ l s e r v i c e = dynamic_cast <greetdemo : : G r e e t P r o v i d e r ∗ >( s e r v i c e ) ; o b j e c t −>r e m o v e G r e e t P r o v i d e r ( l s e r v i c e ) ; } } // e x t e r n "C" Simon Chemouil Universal Declarative Services
    • Motivation Implementation Challenges in C++ Going Universal Dening components SummaryIt works! But. . . The proof-of-concept is successful: We have components wired dynamically OSGis patterns work nicely (yet a bit more tricky) We support the use cases we need Dynamic arrival, thread-safety planned but unnished, service removal to do. But no one would write that wrapper code! Are there solutions to help us here? Simon Chemouil Universal Declarative Services
    • Demo Time!
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryC++ is too complex! Automatically generating the wrappers? Where to get the description? Macros? Parsing C++?! Xtext Java tooling to dene DSLs and compilers Generates an Eclipse editor! Uses EMF as backend, so more can be built upon. Simon Chemouil Universal Declarative Services
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryBack to GreetManagerImpl! Denition component g r e e t d e m o . G r e e t M a n a g e r I m p l { provides { greetdemo . GreetManager } references { dynamic s e r v i c e greetdemo . G r e e t P r o v i d e r [0..n] } } Simon Chemouil Universal Declarative Services
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryDening multiple components Denition module DSDemo { name = "DS G r e e t Demo" version = 1.0.0 includes { greetdemo . E n g l i s h G r e e t P r o v i d e r greetdemo . F r e n c h G r e e t P r o v i d e r greetdemo . GreetManagerImpl greetdemo . C o n s o l e G r e e t e r } } Simon Chemouil Universal Declarative Services
    • Generating C++ code
    • Demo Time!
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryImproving our ADL The ADL we designed maps to Declarative Services capabilities What about richer component models? Creating new target language back-ends Java/DS, Java/iPojo Making it extensible Simon Chemouil Universal Declarative Services
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryBridging Java and C++ Using Remote OSGi Services: An idea discussed in NativeOSGi. We expose C++ services where we can generate a Java interface Use JNI/JNA bindings or network. Basically, we bridge the two service registries! It does sound like CORBA Simon Chemouil Universal Declarative Services
    • Motivation Implementation Simpler Component Denitions Going Universal Whats next? SummaryCreating UI Tools Textual DSLs are nice... But component diagrams are nicer! Up-to-date component metadata is extremely useful: Forces high-level design (round-trips between architects and developers) Allows code generation/rapid project bootstrapping Static analysis (code conformance) Can be used for SDK documentation. Long term project! Simon Chemouil Universal Declarative Services
    • Motivation Implementation Conclusion Going Universal SummaryDeclarative Services for C++ We have been using Ds4Cpp for a few months! If you want to try it. . . you can! We just open sourced it (Apache Software License 2.0) https://github.com/Global-Vision-Systems/Ds4Cpp (the demo is packaged with it)! We need testers and eyes to x my bad C++ :-) And remove the limitations (talk to me!) Simon Chemouil Universal Declarative Services
    • Motivation Implementation Conclusion Going Universal SummaryUniversal Components Tooling The tooling has still some rough edges Enough for our current needs. . . Some clean-up required. We have a roadmap for the improvements. Simon Chemouil Universal Declarative Services
    • Motivation Implementation Conclusion Going Universal SummaryUniversal Declarative Services Questions? Twitter: @simach simon.chemouil@global-vision-systems.com Simon Chemouil Universal Declarative Services