1. OO-Design in PHENIX PHENIX, a BIG Collaboration A Liberal Data Model
Simple (and fast) DST I/O
Design Patterns
OO-Database, an example for the abstract extreme
Does it really work?
Ergo. . .
CHEP-2000
Matthias Messer, BNL

2. Under Construction . . . Software infrastructure CHEP-2000
Matthias Messer, BNL

3. From RAW to DST Official Language is C++
FORTRAN legacy now only in simulation (GEANT 3)
200,000 lines of code and still growing fast
Limited manpower and financial resources
How unusual, what?
Usage of many free open-source packages
Linux, automake, Root, Bonsai, CVS, CLHEP (well, sort of)
many more
Good experience as compared to commercial software
Maintenance(!), upgrades, necessary modifications
CHEP-2000
Matthias Messer, BNL

4. PHENIXians Picture shows only a third of the collaboration
Many developers
Ideas
Strong opinions about programming
Software infrastructure has to integrate them all
CHEP-2000
Matthias Messer, BNL

5. A Liberal OO Model Old OO: Everything is one grand song
Have a (preferably) complete design before you start coding
Work done by experienced OO-programmers
Well . . .
Liberal OO: Have it your way
Data-objects with some methods
method-collections (functors) with some data-members
shallow inheritance structures for modularity
Independently designed packages work on one data-structure
Composite Objects: A node-tree to hold (and share) data
CHEP-2000
Matthias Messer, BNL

6. PHOOL, The PHENIX OO Library
Composite Objects: A node-tree to hold (and share) data
Composite Nodes
Data Node
CHEP-2000
Matthias Messer, BNL

7. PHNode the Data-Classes
Data node is template
type-safe
But all inherit from PHNode
Navigation class PHNodeIterator uses Polymorphism
PHNodeIterator
Unix-like navigation
cd(“ . . .”)
find(“ . . .”)
Can use abstract strategies
for_each(PHStrategy)
CHEP-2000
Matthias Messer, BNL

8. PHModule the Functor Classes
Method-container class
common interface or entry-point, the event() function
Can be used with a PHModuleManager
PHDataNode<PHModule> for implementation of strategies
CHEP-2000
Matthias Messer, BNL

9. Abstract Strategies Used in Node tree Used in Module Manager
apply a method to all nodes of a branch
Used in Module Manager
call event() function of all Modules in the collection: the event-loop
CHEP-2000
Matthias Messer, BNL

10. OODBs in PHENIX Two autonomous partitions Counting House
RCF (RHIC Computing Facility)
Robust against the ‘bulldozer incident’
The picture shows a subset
Pdbcal is only one of many DB applications, but
The one most of all used in reconstruction code
The biggest data volume
order of Tbyte/Year
CHEP-2000
Matthias Messer, BNL

11. Pdbcal a user-friendly database-application
small set of wrapped control-classes
start, end transactions
easily expandable by the user himself
provide a storage class (e.g. a hardware-channel)
gets picked up by code-generators for integration into the DB-package
you handle only a very abstract (2.5 layers) bank-class
applications do not depend on later generated code
transparent low-level activity
Open a new DB-file when 2 Gbyte limit is reached
traverse from Tag-DB to calibration-DB
CHEP-2000
Matthias Messer, BNL

12. Data-Storage in Objy/Root
No need for elaborate design of the base classes
concentrate on functionality and on ONE application (objy) for now
add Root I/O later by way of inheritance
transparent for the user interface
CHEP-2000
Matthias Messer, BNL

13. Useful (and used) Design-Patterns
singletons
database application manager
a classmap hash-table (STL-map)
abstract base-classes and factories
change low-level applications without changing interfaces
Objectivity Root
protect the user from implementation details (and vice versa)
composite objects
flexible, yet type-safe node-tree
abstract strategies
standardized operations on no-tree-data
great flexibility in choosing analysis methods
CHEP-2000
Matthias Messer, BNL

14. The Very Real Life . . . . . . of simulated data processing
MDC: Mock Data Challenge
two weeks of simultaneous
data sinking into HPSS
data mining from HPSS
parallel data processing using the PHOOL environment
the new reconstruction software
is fast:
30s / event is factor two faster than with old data-model (STAF)
is reliable:
few crashes, none related to memory-management in the reconstruction code
no memory leaks (non trivial in such a liberal data-model)
CHEP-2000
Matthias Messer, BNL

15. In Somma . . . The relaxed OO-philosophy (PHOOL)
has:
slightly more separation between data and methods
shallow inheritance trees
you buy what you want, or
“I don’t want a three-vector that can send me ”
can:
integrate many peoples software efforts
allow flexible usage of outside-packages
The approach of the abstract extreme (Pdbcal)
shields user, prevents fear of first contact
maintains flexibility in usage of low-level software
Contact
more info:
CHEP-2000
Matthias Messer, BNL