Athena Developer Guide

Athena
Chapter 7 Accessing data Version/Issue: 2.0.0
Chapter 7
Accessing data
7.1 Overview
The data stores are a key component in the application framework. All data which comes from
persistent storage, or which is transferred between algorithms, or which is to be made persistent must
reside within a data store. In this chapter we use a trivial event data model to look at how to access data
within the stores, and also at the DataObject base class and some container classes related to it.
We also cover how to define your own data types and the steps necessary to save newly created objects
to disk files. The writing of the converters necessary for the latter is covered in Chapter 15.
7.2 Using the data stores
There are four data stores currently implemented within the
Listing 7.1 Example job options using Sequencers demonstrating inverted logic
1: ApplicationMgr.DLLs += { "GaudiAlg" };
2: ApplicationMgr.TopAlg = { "Sequencer/Seq1", "Sequencer/Seq2" };
3:
4: // Setup the next level sequencers and their members
5: Seq1.Members = {"HelloWorld", "Prescaler", "EventCounter/Counter1"};
6: Seq2.Members = {"HelloWorld", "Prescaler:invert",
"EventCounter/Counter2"};
7:
8: Prescaler.PercentPass = 80.;
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