1 / 23

Introduction to Gaudi

Introduction to Gaudi. LHCb Software Strategy. Develop an Architecture (‘blueprint’) and a Framework (real code) to be used at all stages of LHCb data processing HLT, simulation, reconstruction, analysis Avoid fragmentation and duplication of computing efforts

pilar
Download Presentation

Introduction to Gaudi

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Gaudi LHCb software tutorial - September 2011

  2. LHCb Software Strategy • Develop an Architecture (‘blueprint’) and a Framework (real code) to be used at all stages of LHCb data processing • HLT, simulation, reconstruction, analysis • Avoid fragmentation and duplication of computing efforts • Transparent use of third-party components wherever possible • Applications are developed by customizing the Framework LHCb software tutorial - September 2011

  3. Software Organization Applications built on top of frameworks and implementing the required algorithms. Reconstruction Simulation High level triggers Analysis • One framework for basic services • + various specialized frameworks: • detector description, visualization, persistency, interactivity, simulation, etc. Frameworks Toolkits A series of widely used basic libraries: Boost, GSL, Root etc. Foundation Libraries LHCb software tutorial - September 2011

  4. What is a Framework? [1] G. Booch, “Object Solutions”, Addison-Wesley 1996 • Framework Definition [1,2] • An architectural pattern that codifies a particular domain. It provides the suitable knobs, slots and tabs that permit clients to use and adapt to specific applications within a given range of behavior. • In practice • A skeleton of an application into which developers plug in their code, and which provides most of the common functionality. • Benefits • Common vocabulary, better specifications of what needs to be done, better understanding of the system. • Low coupling between concurrent developments. • Smooth integration. • Robustness, resilient to change (change-tolerant). • Fostering code re-use [2] E. Gamma, et al., “Design Patterns”, Addison-Wesley 1995 LHCb software tutorial - September 2011

  5. Gaudi Architecture • GAUDI is an architecture and framework for event-processing applications (simulation, reconstruction, etc.) • Initially developed for LHCb, it has been adopted and extended by ATLAS and adopted by several other experiments including Fermi Space Telescope, HARP, Minerva, Daya Bay • Main Design Choices best illustrated by looking at the Gaudi Object diagram • A snapshot of the components in memory, once the job is initialized and running LHCb software tutorial - September 2011

  6. Gaudi Object Diagram Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  7. Separation between “data” and “algorithms” Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  8. Three basic categories of datacharacterized by their “lifetime” in the job Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  9. Separation between “transient” and “persistent” representations of the data Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  10. Data store-centered (“whiteboard”) architectural style Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  11. “User code” encapsulated in few specific places Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  12. Well defined component “interfaces” Converter Converter Application Manager Converter Event Selector Data Files Message Service Persistency Service Event Data Service Transient Event Store JobOptions Service Algorithm Algorithm Algorithm Data Files Transient Detector Store Particle Prop. Service Persistency Service Detec. Data Service Other Services Data Files Transient Histogram Store Persistency Service Histogram Service LHCb software tutorial - September 2011

  13. Gaudi Interface model ISvcLocator ApplicationMgr IDataProviderSvc IProperty IAlgorithm EventDataSvc Concrete Algorithm IDataProviderSvc DetectorDataSvc IHistogramSvc HistogramSvc Obj_A Obj_B MessageSvc IMessageSvc ToolSvc IToolSvc LHCb software tutorial - September 2011

  14. Laptop Interface Model IDVIConnector IWiFiPort IVGAConnector • Each interface is specialized in a domain. • Interfaces are independent of concrete implementations. • You can mix devices from several constructors. • Application built by composing. • Standardizing on the interfaces gives us big leverage. IKeyboard IUSBConnector LHCb software tutorial - September 2011

  15. Electrical plug interface model Don’t define too many interfaces for the same job! LHCb software tutorial - September 2011

  16. Interfaces in Practice IMyInterface.h class IMyInterface: virtual public IAlgTool { virtual double doSomething( int a, double b ) = 0; } MyDoSomethingTool.h #include “IMyInterface.h” class MyDoSomethingTool : public GaudiTool, virtual public IMyInterface { inline double doSomething( int a, double b ) { return b * (double)a; } } LHCb software tutorial - September 2011

  17. ClientAlgorithm.cpp #include “IMyInterface.h” ClientAlgorithm::myMethod() { // Declare the interface IMyInterface* myInterface; // Get the interface from somewhere myInterface = tool<IMyInterface>(“MyDoSomethingTool”); // Use the interface double result = myInterface->doSomething( 10, 100.5); } LHCb software tutorial - September 2011

  18. Gaudi Component Model • Algorithms, Converters, Services and Tools are known as Components • Self contained objects with behaviour • Loaded at run time from component libraries (“plugins”) • Interact with the framework and with each other via Interfaces • Behaviour controlled by Properties (“Job options”) • Algorithms are where users interact with the framework • Implement three methods invoked by the framework • initialize() called once at the start of the job • execute() called in the event loop, once per event • finalize() called once at the end of the job • Communicate with each other via the Transient Event Store LHCb software tutorial - September 2011

  19. Algorithm & Transient Store Data T1 Data T1 Transient Event Data Store Data T1 Algorithm A Data T2, T3 Data T2 Algorithm B Data T4 Data T3, T4 Algorithm C Apparent dataflow Data T5 Real dataflow Data T5 LHCb software tutorial - September 2011

  20. Tools and Services • Algorithms have some limitations • Only called once per event, only share data via TES • What about private data? • Tools are components providing algorithmic functionality • Callable many times per event, through specific interface and with arguments • IBdlTool, IDistanceCalculator, IHltSummaryTool, IMassVertexFit, IProtoParticleFilter, ISTReadoutTool, ITrackFitter…. • Can be private: owned and accessible only by the component creating it • Or public: owned by the framework and accessible globally • Services: • Similar to public tools, created by framework to provide global functionality • Job Options Service, Message Service, Particle Properties Service, Event Data Service, Histogram Service, Ntuple Service, Detector Data Service, Magnetic Field Service, Random Number Service, Persistency Services… LHCb software tutorial - September 2011

  21. Data • Data Object • Atomic data unit (visible and managed by transient data store) • No algorithmic code • Transient Data Store • Central service and repository for data objects • Manages data location, life cycle, load on demand, … • Data Converter • Provides explicit/implicit conversion from/to persistent data format to/from transient data LHCb software tutorial - September 2011

  22. Gaudi Product Sheet • Current release • v22r4 (Sep 2011) • Supported Platforms • Scientific Linux (CERN) 5 & gcc 4.3 on x86_64 and i686 • Scientific Linux (CERN) 5 & icc 11 on x86_64 • Windows XP & VisualC++ 9 on i686 • (gcc 4.3 with OSX 10.6) • Web address. • http://cern.ch/proj-gaudi/ LHCb software tutorial - September 2011

  23. Documentation • Gaudi User Guide • A 220 pages document targeted to end-users • FAQ: Mixture of Gaudi and LHCb specific topics • https://twiki.cern.ch/twiki/bin/view/LHCb/FAQ/LHCbFAQ • C++ Documentation (generated from code) • Doxygen: • Uses special comments in code, e.g. Tutorial solutions • http://cern.ch/proj-gaudi/releases/latest/doxygen/ • Lbglimpse: indexed search within released code • Lbglimpse <search string> <Project> <version> • LbglimpseIJobOptionsSvc Gaudi v22r4 • Self help mailing lists: • lhcb-soft-talk@cern.ch, gaudi-talk@lists.bnl.gov LHCb software tutorial - September 2011

More Related