Migrating CRISTAL from Objectivity to RDBMS

Andrew BransonUniversity of the West of England

CERN, 13/01/2014

CRISTAL

• Production tracking system for CMS– Project started 1996– Tracked construction of CMS ECAL Barrel, Endcap,

ECAL Electronics, Preshower.– Ran at CERN and other sites, or imported data from

other remote construction software• Extremely object-oriented concept.• Objectivity was an obvious choice.

CRISTAL 1

• Objectivity-based prototype (CRISTAL 1) completed 2000

• Collected prototype data:– Crystals and test ECAL modules at CERN and INFN,

Rome– APD capsules at IN2P3, Lyon.

• C++ backend, Java UIs.• Heavily integrated with OO DB, required

extensive re-engineering to migrate to alternative database.

Redesign

• Prototype had design problems.• Object DBs had failed to catch on, support

waning at CERN.• Large amount of work to remove Objectivity.• Small amount of production data to migrate.

Decision made to redesign and redevelop from scratch

CRISTAL 2

• Production system deployed August 2003• Storage still object based, but with abstraction

layer.• Plugins for Oracle, MySQL, SQLite.• Fall-back XML file serialization.

CRISTAL 2

• Application design implemented using descriptions - metamodels.

• XML (text) based. Portable, human readable.• Self-documenting, web standards (XSD)

– Some preservation against technology obsolescence

• Investigating migrating to XMLDB for enhanced query capability.

Conclusion

Technology dependency comes in two flavours:• Dependency on Implementation– Prevent redesign through abstraction.– Small, self-contained redevelopment when obsolete.

• Dependency on Philosophy– Could require large re-engineering.– Only protection is to safeguard data, schema and logic

in a documented form that could be reinterpreted in the future.

End