The Catalog is part of the Offline Database. At Fermilab, this database is implemented using Oracle. Tools and interfaces have been implemented to allow the database to be a freeware product such as MSQL A flat file implementation is also in the design.
The Oracle Offline Database, has three instances:
The interface to the Catalog tables, for use in CDF jobs, is provided both as a set of command line tools and as an API for C++ programs. The CDF CVS package "DataFileDB" contains both. This package is part of a unified set of packages which service all tables, including the Calibration tables, in the Offline Database. The DataFileDB package contains much documentation about the package itself and, more generally about the Catalog.
The web browser, explained on the Catalog Contents
and Browser page, accesses the Oracle database directly using Oracle
client SQLPLUS and thus does not use tools or classes in DataFileDB. The
browser does not thus transparently switch between Oracle and msql instances
of the offline database.