Transcript PhDOOS’99 Object Databases in the LHCb experiment

PhDOOS’99
Object Databases in the LHCb
experiment
Radovan Chytracek
LHCb experiment
CERN, Switzerland
Background
• 4 CERN experiments in the LHC1 era
– ATLAS, CMS, Alice, LHCb
• Software moving towards OO systems
– transition from FORTRAN to C++
– RDBMS to ODBMS
• Large detectors
– composed from many elements (~106)
– detector description needed by almost all apps
• on-line, simulation, reconstruction, analysis, etc.
• logical structure, geometry, calibration, alignment, el.
channel maps, magnetic field
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Large Hadron Collider
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Background
• Large data amounts expected
– order of magnitude in PB(1015 Bytes) per year
• Data have WORM feature
– written once read many times
– processing unit is collection of events
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Data processing
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GAUDI Framework
• Project in the LHCb experiment
– cover all data processing stages, interactive and
batch environments
• Strategic design choices
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Separation between data and algorithms
Data: event, detector, statistical data
Separation between persistent and transient data
Data centered architectural style
User code goes into algorithms and converters
Components with well defined interfaces
Reusability
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GAUDI Architecture
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Detector Description
DataBase
Versioning
Identification
identification and naming
versioning schema
version numbers and tags
versioning in time
Detector Geometry
Logical Description
geometry volumes
hierarchy
solids, dimensions,
position, transformation
logical detector hierarchy
user entry point
navigation through the
detector hierarchy
links to the other DDDB
modules
Material
material and
physics constants
Condition
Mapping
Field
alignment
calibration
slow-control
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electromagnetic
maps of the
various detector
parts
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DDDB Data Versioning
Version
Production version:
VDET: v3 for T<t3, v2 for t3<T<t5, v3 for t5<T<t9, v1 for T>t9
HCAL: v1 for T<t2, v2 for t2<T<t8, v1 for T>t8
RICH: v1 everywhere
ECAL: v1 everywhere
Time
VDET alignment
HCAL calibration
RICH pressure
ECAL temperature
t1
t2
t3
t4
t5 t6
t7
t8
t9
t10
t11
Time = T
Data type
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DDDB Transient model
DataObject
Material
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0..nMaterial
DetectorElement
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Mother Volume
Geometry
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Physical
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1..n
Solid
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Solid
Placed Logical
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parent <-> daughter
relationship done by
objects of Registry
Entry class (not
LogicalVolume
n
Daughter Volumes
0..n
Tube
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Sphere
Box
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