The Design of the BABAR
Database Management System

David R. Quarrie

Version Information

Draft: 05th May 1998

This document is still under development. If you have any questions or comments, please address them to the author.

Table of Contents

• Introduction
• Domains
• Authorization Levels
• Applications
• Directory & File Organization
• References

Introduction

This document describes the global design of the BABAR integrated Database Management System. It introduces the concepts and terminology that describe the components of the system, together with some design guidelines.

The design is based upon the principles of the Object Database Management Group (ODMG) as described in the ODMG-93 standard document.

Several companion documents complement this one and extend the design into several domains (see next section).

Domains

The BABAR database management system is comprised of three basic domains:

The design should be extensible to accommodate additional domains.

Authorization Levels

An application can be executed in one of several authorization levels. The level determines certain access rights to the contents of the database and may restrict the ability of the application to update the contents. Available authorization levels are:

• System. An application operating at this level has full control over the database, allowing it read, update, create and delete privileges.
• Group. An application operating at this level has read-only access to the database apart from databases and contents corresponding to a specified group. Groups are intended to correspond to physics analysis work-groups and similar. Information from the other authorization levels and other groups may be replicated within the context of the current group.
• User. When operating at this level, the application has read-only access to the database apart from databases and contents corresponding to a specified user. Users correspond to UNIX accounts [SLAC AFS Accounts?]. Information from the other authorization levels and other users may be replicated within the context of the current user.

Authorization levels are domain-specific, and an application may execute at one authorization level for one domain (e.g. Conditions database access) and at another level within another domain (e.g. Event Store access).

By default an application operates at User authorization level for each domain, granting it restricted access to the database. It may request a higher level of authorization within each domain separately, but this will only be successful if previously granted by the database administrator.

Applications

All applications using the BABAR database access information via a single BdbApplication class. This performs transaction and error reporting management as well as statistics gathering. This provides access to the event dictionaries that themselves provide access to named collections of events. The BdbApplication class is implemented as a singleton and thus provides a single instance through which all management must be performed.

Directory & File Organization

Directory Tree

$BDBROOT/ -+- conditions/ --- [...]
           |
           +- events/ --- [...]
           |
           +- online/ --- [...]

References

1. Object Database Management Group, The Object Database Management Group Standard, 1993
2. ATLAS Collaboration, ATLAS Computing Technical Proposal, CERN/LHCC 96-43, Dec1996.

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