Athena Developer Guide

Athena
Chapter 18 Framework packages, interfaces and libraries Version/Issue: 2.0.0
Chapter 18
Framework packages, interfaces and
libraries
18.1 Overview
It is clearly important to decompose large software systems into hierarchies of smaller and more
manageable entities. This decomposition can have important consequences for implementation related
issues, such as compile-time and link dependencies, configuration management, etc. A package is the
grouping of related components into a cohesive physical entity. A package is also the minimal unit of
software release.
In this chapter we describe the Gaudi package structure, and how these packages are implemented in
libraries.
18.2 Gaudi Package Structure
The Gaudi software is decomposed into the packages shown in Figure 18.1..
At the lower level we find GaudiKernel, which is the framework itself, and whose only dependency
is on the GaudiPolicy package, which contains the various flags defining the CMT [6]
configuration management environment needed to build the Gaudi software. At the next level are the
packages containing standard framework components (GaudiSvc, GaudiDb, GaudiTools,
GaudiAlg, GaudiAud), which depend on the framework and on widely available foundation
libraries such as CLHEP and HTL. These external libraries are accessed via CMT interface packages
which use environment variables defined in the ExternalLibs package, which should be tailored to
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