Using HEPDB - an example scenario

Suppose some high energy physics institute has an experiment involving the use of some large detector within which the knowledge of geometrical and calibration parameters is of great importance in order to aid the understanding of systematical errors.

The database to contain these parameters giving a full description of our apparatus should therefore try to satisfy the following criteria:

1. Allow fast and simple access to large amounts of stored data
2. Provide portability between different platforms
3. Offer the capability to handle frequent updates
4. Provide an interactive interface for issuing commands to the database as well as FORTRAN library routines
5. Provide files which can easily be accessed from users own applications

Further problem definition

We shall now examine generally the type of procedures that must be followed to allow the implementation of a set of databases under HEPDB bearing in mind that the new databases must be built from scratch and that we want to cause the minimum possible disruption to the existing software that an experiment may already be using.

Suppose now that some experimental group who currently use the RZ file system for keeping data regarding the geometric, calibration and auxiliary data of a detector decide that a change to the HEPDB database management system would give them more flexibility with their data.

The following pages of this tutorial aim to give a general overview in the steps involved with such a conversion , stopping also to describe some other interesting features of the package.

The general plan for the conversion would be as follows:

1. Set up a server for HEPDB
2. Create the new destination databases
3. Convert existing databases to the HEPDB format including any changes to the existing structure (keys, directories etc.).
4. Construct a compatibility mode interface to existing experimental software.