The A4 project: physics data processing using the Google protocol buffer library

Understand

In this paper, we present the High Energy Physics data format, processing toolset and analysis library a4, providing fast I/O of structured data using the Google protocol buffer library.

• The overall goal of a4 is to provide physicists with tools to work efficiently with billions of events, providing not only high speeds, but also automatic metadata handling, a set of UNIX-like tools to operate on a4 files, and powerful and fast histogramming capabilities.
• At present, a4 is an experimental project, but it has already been used by the authors in preparing physics publications.
• We give an overview of the individual modules of a4, provide examples of use, and supply a set of basic benchmarks.