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SEAL Framework & Services

LCG AA Internal Review 20 October, 2003 Radovan Chytracek / CERN on behalf of SEAL team. SEAL Framework & Services. Motivation. Allow LCG developers and users to write portable and modular code across all LCG projects Provide developers with handy abstractions for modeling software systems

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SEAL Framework & Services

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  1. LCG AA Internal Review 20 October, 2003 Radovan Chytracek / CERN on behalf of SEAL team SEALFramework & Services

  2. Motivation • Allow LCG developers and users to write portable and modular code across all LCG projects • Provide developers with handy abstractions for modeling software systems • Learn from mistakes in the past and come with software component system which gets the best ideas which work well in existing systems 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 2

  3. Requirements • There are simply too many to list here • Too many parties and interests involved • Very often controversial between two parties • Inspired by technologies in HEP and outside • Gaudi, Iguana, J2EE, Qt, COM, .NET, Python • Basic requirements: • KISS, flexible, type-safe, fast(if possible) • Features: • contextual composition, type-safe lookup, abstract interface support, plug-ins friendly 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 3

  4. Requirements (2) • Encourage well-known communication protocols • call-backs, signals/slots,, observer-notification • Encourage simple services • direct use, targeted interfaces • configurable components via state/contextinstead of a->b->c->d style of navigation • Aim at lightweight framework, simple, repeatable usage pattern • common wiring, not a lot imposed on experiment framework • Component model must fit needs of majority and must be easily adopted by the rest

  5. How we did it • Baseline taken from Iguana component system • Re-design followed to make it independent • The design we agreed was first prototyped in Python • Focus on functionality & component collaboration apects • 2 quick independent C++ prototypes followed • The first goal to achieve the Python prototype look-alike • The second to achieve minimal amount of code needed to build and use components in a C++ application • Internal review of the prototypes • Benchmark, C++ implementations comparison, identifying performance bottle-necks and points of inflexibility

  6. ComponentFactory ComponentLoader RefCounted Component Context Service MyComponent MyService Component Model • Designed as hierarchy of bases classes to support the component model • Each Component lives in a Context • Contexts form their own hierarchy • Support for component look-up • If not in local context, look in parent • A Service provides its own local Context • Components of a Service live in the scope defined by its own Context • User classes inherit from Component or Service • Plug-in functionality for free * 1 1 * 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 6

  7. Application C1 C1 C2 C1 C5 C1 Svc1 Svc2 C3 C1 C4 C1 C1 C6 C7 C1 Svc1 C7 C1 Context Hierarchy • Any Component may attempt to locate another Component in the running application (collaboration network) • By “type” or by “key” • If the not found in the current context, the parent context is searched recursively Context Component Service 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 7

  8. #include "SealKernel/Component.h“ class MyComponent : public seal::Component{ DECLARE_SEAL_COMPONENT; public: MyComponent (seal::Context* context); MyComponent (seal::Context* context, const std::string & label); // implicit copy constructor // implicit assignment operator // implicit destructor //.....component member functions.. void doSomething(); }; MyComponent.h Component Model: How-To (1) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 8

  9. #include "MyComponent.h“ #include <iostream> DEFINE_SEAL_COMPONENT (MyComponent, "seal/example/MyComponent"); MyComponent::MyComponent (seal::Context* context) : Component (context, classContextKey ()){} MyComponent::MyComponent (seal::Context* context, const std::string & label) : Component (context, label){} // member function implementations void MyComponent::doSomething() { std::cout << "MyComponent: Hello World ! " << std::endl; } MyComponent.cpp #include "MyComponent.h“ #include "SealKernel/ComponentFactory.h“ #include "PluginManager/ModuleDef.h“ DEFINE_SEAL_MODULE (); DEFINE_SEAL_PLUGIN (seal::ComponentFactory, MyComponent, MyComponent::classContextLabel ()); Module.cpp Component Model: How-To (2) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 9

  10. #include “SealKernel/ComponentLoader.h” #include “MyComponent.h” Handle<MyComponent> handle = component<MyComponent>(); handle->doSomething(); OtherComponent.cpp Look-up by type #include “SealKernel/ComponentLoader.h” #include “MyComponent.h” Handle<MyComponent> handle = component<MyComponent>( “seal/example/MyComponent2” ); handle->doSomething(); OtherComponent1.cpp Look-up by key Component Model: How-To (3) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 10

  11. IFace.h class IFace { public: virtual void ifaceCall(void)=0; virtual ~Iface(){} }; IFaceComponent.cpp class IFaceComponent : public IFace, public Component {public: DECLARE_SEAL_COMPONENT; IFaceComponent( Context* c ) : Component( c, IFaceComponent::classContextKey() ) {} IFaceComponent( Context* c, const ContextKey& key ) : Component( c, key ) {} IFaceComponent( Context* c, conststd::string& key ) : Component( c, key ) {} virtual ~IFaceComponent() {}public: // IFace implementationvirtual void ifaceCall(void);};DEFINE_SEAL_COMPONENT(IFaceComponent,"seal/example/IFaceComponent")void IFaceComponent::ifaceCall(void) { MessageStream optimist( this, "Optimistic" ); optimist << "I live!" << flush;} Using abstract interface Main.cpp #include "IFace.h"intmain(){ Application theApp; Handle<ComponentLoader> loader = theApp.context()->component<ComponentLoader>(); loader->load("seal/example/IFaceComponent");IHandle<IFace> ifacehandle = theApp.context()->query<IFace>("seal/example/IFaceComponent");if( ifacehandle ) ifacehandle->ifaceCall();return 0;} Component Model: How-To (4) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 11

  12. Basic Framework Services • The first set of Basic Services came with the new Component Model • Application • Defines the top level Context • Possibility to set the initial set of Components to be loaded in the application • Message Service • Message composition, filtering and reporting • Closely related to MessageStream • Configuration Service • Management of Component properties and loading configurations • Multiple backends foreseen: • Gaudi style options, .INI style, CMS style, XML, ... 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 12

  13. Future development • New Services • Whiteboard service • Design started and discussed with the interested experiments • Waiting for feedback from experiments • Implementation plan similar to that of component model • DictionaryService - loading of dictionary libraries on-demand • Design and prototyping in progress • More ConfigurationService back-ends • Get feedback (from experiments + POOL+…) about Component model and Framework services • Corrections and re-designs are foreseen and possible 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 13

  14. Summary • Component model & basic services came with SEAL 1.0.0 • Combining existing designs into a “common” one is not trivial • Base classes to support the model provided • First set of basic Framework services • Ready to be used (tested) by experiments frameworks, however: • POOL is waiting for the component model to stabilize • LHCb may jump on it after POOL integration in Gaudi is O.K. • CMS similar attitude as LHCb, going for minimalist approach • ATLAS not there yet 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 14

  15. int main(int,char**) { Application theApp; //----Get Loader Handle<ComponentLoader> loader = theApp.component<ComponentLoader>(); //----Instantiate the plug-in loader->load("SEAL/Kernel/Test/Loadable"); //----Get a handle to it Handle<Loadable> loadable = theApp.component<Loadable>(); } main.cpp Application • Establishes the “top” Context • But, it can be inserted in an exiting Context • Instantiates a basic number of Components (or Services) useful to all applications • ComponentLoaded (interface to Plug-in manager) • PropertyManager (application level configuration parameters) • MessageService • ConfigurationService 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 15

  16. #include “SealKernel/MessageStream.h” MessageStream info( this,”MyName”, MSG::INFO); info << “Hello world” << flush; MessageStream log( this, “OtherName”); log(MSG::ERROR) << “This is an error” << flush; OtherComponent.cpp MyName INFO Hello World OtherName ERROR This is an error output Message Service • The user instantiates a MessageStream to compose messages. It reports to the MessageService when message is completed • MessageService dispatches and filters all messages of the application 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 16

  17. Component.cpp struct callObj { operator()(const Propertybase&) {…} }; int m_int; Property<double> m_double(“double”, 0.0,”descr”, callObj); propertyManager()->declareProperty(“int”, m_int, 0, “descr”); propertyManager()->declareProperty(m_double); Configuration Service • A Component may declare its own Properties • Templated Property instances (any type with a stream operator<<) • References to data members (any type with a stream operator<<) • Possibility to associate “callback” update function • Properties have a “name” (scoped) and a “description” • The PropertyCatalogue is the repository of all properties of the application • It is filled from the “configuration file” (Gaudi JobOptions format currently) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 17

  18. ? Mapping from labels to keys to objects A a 0 TopContext B b 1 f e g b d 8 a c next h 6 7 0 1 2 3 4 5 C c 2 1 3 5 7 0 2 4 6 A B H D d 3 E e 4 0 1 2 3 4 5 Child Context 1 0 1 2 3 Child Context 2 F f 5 F D G g 6 H h 7 Handle Context::query(“key”) { return m_vec[ ContextKey::m_keys[“key”] ] } Single Context Look-up object model ContextKey 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 18

  19. SEAL Team (credits) • Christian Arnault (Dictionary) • Radovan Chytracek (Foundation, Framework) • Jacek Generowicz (Scripting, Framework, Documentation) • Fred James (MathLibs) • Wim Lavrijsen (Scripting) • Massimo Marino (Foundation, Framework, Scripting) • Pere Mato (Framework, Dictionary, Scripting) • Lorenzo Moneta (Foundation, Framework) • Stefan Roiser (Dictionary) • RD Schaffer (Dictionary) • Lassi Tuura (Foundation, Framework, Infrastructure) • Matthias Winkler (MathLibs) • Zhen Xie (Dictionary) 20 October 2003 SEAL Review - Framework & Services R. Chytracek/CERN 19

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