1. SW Architecture SG meeting 22 July 1999 P. Mato, CERN
GAUDI Architecture
SW Architecture SG meeting
22 July 1999
P. Mato, CERN
The following are few slides intended to trigger a discussion/brainstorming with the goal of producing an Architecture for the DCS kernel.
Definition on Architecture: “The architecture of a system is the structure of the system”. Two main ingredients: A set of building blocks, and a set of collaborations that specify how those building blocks cooperate to provide various system functions.
An DCS architecture will allow us to provide set of control applications or control systems that fulfill a range of needs within the DCS domain. An architecture encourages reuse.
Analogies in the real world: Gothic architecture, Lego Basic® architecture, Lego Technique® architecture.
“To be successful, an object-oriented project must craft an architecture that is both coherent and resilient and then must propagate and evolve the vision of this architecture to the entire development team”, G. Booch, Object Solutions.
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GAUDI Framework

2. GAUDI: Scope
We want to develop a Framework to be used in ALL the LHCb event data processing applications in all stages: high level trigger, simulation, reconstruction, analysis.
Control applications are not included (slow control, run control)
The bulk of the LHCb data processing software will be developed by physicists.
Components will be developed using other frameworks (GUI, object persistency, simulation, …)
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GAUDI Framework

3. GAUDI: Goals To develop a framework
The framework should be customizable to provide solutions to the event data processing needs.
It should:
Allow physicists to focus on solving the physics problem.
Easy to use
Non physics-related functionality implemented by the framework
Ensure low coupling between concurrent developments.
Guarantee a later smooth integration of developments.
Facilitate software re-use
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GAUDI Framework

4. Software Structure
A series of data processing applications built on top of the frameworks and implementing the required physics algorithms.
High level triggers
Reconstruction
Simulation
Analysis
A series of Frameworks and Toolkits. One main framework: GAUDI, various specialized frameworks: visualization, persistency, interactivity, simulation (Geant4), etc.
Frameworks
Toolkits
A series of basic libraries widely used: STL, CLHEP, etc.
Foundation Libraries
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GAUDI Framework

5. Major design criteria Clear separation between “data” and “algorithms”
Three basic types of data:
event data (data obtained from the particle collisions)
detector data (structure, geometry, calibration, alignment, environmental parameters,..)
statistical data: (histograms, …)
Clear separation between “persistent data” and “transient data”.
Isolation of user’s code.
Different/incompatible optimization criteria.
Transient as a bridge between various representations.
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GAUDI Framework

6. Major design criteria (2)
Data store centered architectural style.
Algorithms as data producers and consumers.
User code encapsulated in few specific places:
“Algorithms”: Physics code
“Converters”: Converting data objects into other representations
All components with well defined “interfaces” and as “generic” as possible.
Design principles
Coupling, inheritance, static storage, ...
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GAUDI Framework

7. Building blocks
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GAUDI Framework

8. Interfaces 11/22/2018 GAUDI Framework Gaudi Application Framework
IDataProviderSvc
EventDataService
IDataProviderSvc
IAlgorithm
IProperty
DetectorDataService
IHistogramSvc
ConcreteAlgorithm
HistogramService
IMessageSvc
ObjectA
ObjectB
MessageService
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GAUDI Framework
Gaudi Application Framework

9. Algorithms Algorithm A Algorithm B A Algorithm C B C Transient Event
Data T1
Data T1
Each Algorithm only knows what data (type and name) is expecting as input and creating as output.
The only coupling is through the data.
Scheduling of sub-algorithms is responsibility of the parent algorithm.
Real dataflow
Apparent dataflow
Transient Event
Data Store
Data T1
Algorithm A
Data T2, T3
Data T2
Algorithm B
Data T4 A
Data T3, T4
Algorithm C
Parent B
Data T5 C
Data T5
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GAUDI Framework

10. IParticlePropertySvc
Services
Services are provided to Algorithms
Examples:
Job Options service (card files)
Message reporting service
Event/Detector/Histogram data service
Event Selector
Persistency and Conversion services
User Interface (GUI)
Particle property service
...
IService
IProperty PP
File
Particle Prop.
Service
IParticlePropertySvc
Algorithm
Algorithm
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GAUDI Framework

11. Event Data Store Event Data Service Persistency Service Algorithm
retrieveObject( “EcalDigits”,...)
Fetch()
Store()
Event Data
Service
registerObject( “key”,...)
Persistency
Service
Algorithm
creates
Direct
reference
Transient Event Store
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GAUDI Framework

12. Event Persistency SicbCnvSvc Transient Event Store Sicb data Files
Sicb/Zebra
Converter
Event Data
Service
Converter
Converter
Persistency
Service
RootCnvSvc
Algorithm
Algorithm
Root data
Files
Root I/O
Converter
Converter
Converter
AppManager
OutputStream
OutputStream
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GAUDI Framework

13. Detector Description Editors Data Processing Application Editors
Algorithms
Algorithms
Projection view: version & event time
Transient detector store
Persistent Detector Description (DDDB)
Geom
Geom
DetElem
Geom
DetElem
DetElem
DetElem
Calib
Geom
Calib
Slow
DetElem
DetElem
Geom
DetElem
DetElem
DetElem
DetElem
Slow
DetElem
DetElem
Detector
Data
Producers
Conversion
services
Conversion
services
? Update persistency
Other representations
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GAUDI Framework

14. Data Visualization User Interface Representations Conversion Store
(graphical,
textual)
Conversion
Service
Converter
Converter
Converter
Converter
Transient Event/
Detector Store
Selector
User
Interface
Selects objects in store
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GAUDI Framework

15. Application Configuration
What are the knobs at our disposal?
JobOptions. Simple usage. It allows the end-user to overwrite any property of any algorithm or service.
Algorithm/Service properties database. A more sophisticated way to modify the properties of the algorithms and services.
Detector database edition to create new versions or releases.
Write specific code. Configure your application by setting it at runtime.
User interface component. Graphical (a la Visual Basic), command line (scripting language), etc.
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GAUDI Framework

16. Packages GAUDI Framework GaudiExam. RootCnv SicbCnv LHCbAlg DetCnv RIO
(applications)
RootCnv
(converters)
SicbCnv
(converters)
LHCbAlg
(algorithms)
DetCnv
(converters)
RIO
Futio
(SICB)
HbookCnv
(converters)
LHCbEvent
(event model)
DetDesc
(detect. model)
CernLib
CLHEP
Gaudi
(foundations)
STL
Package group
Package dependency
optional
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GAUDI Framework