ROOT: An Object-Oriented Data Analysis Framework

A report on a data analysis tool currently being developed at CERN.
Linux an Increasing Force in Scientific Computing

Analyzing the FTP logs of the more than 9,300 downloads of the ROOT binaries reveals the popularity of the different computing platforms in the mainly scientific community. Figure 4 shows the number of ROOT binaries downloaded per platform.

Figure 4. ROOT Download Statistics

Linux is the clear leader, followed by the Microsoft platforms (Windows 95 and NT together equal Linux). The results for the other UNIX machines should probably be corrected a bit, since many machines are multi-user machines where a single download by a system manager will cover more than one user. Linux and Windows are typical single-user environments.


In this article I've given an overview of some of the main features of the ROOT data-handling system. However, many aspects and features of the system remain uncovered, such as the client/server classes (the TSocket, TServerSocket, TMonitor and TMessage classes), how to automatically generate HTML documentation (using the THtml class), remote database access (via the rootd daemon), advanced 3D graphics, etc. More on these topics can be found on the ROOT web site.



Fons Rademakers received a Ph.D. in particle physics from the University of Amsterdam. Since 1988 he has been working at CERN developing database, data analysis and graphics software. Fons started using Linux in 1993 and has been advocating it ever since. Besides developing ROOT, he is building several Linux PC farms for physics data processing (a joint project with Hewlett Packard). When not programming, he races go-carts and rides his trail bike. He can be reached via e-mail at

Rene Brun received a Ph.D. from the University of Clermont-Ferrand, France. He joined CERN in 1973. Rene made major contributions to the CERN Program Library, creating and coordinating the development of major software projects such as GEANT and PAW. In 1989, he received the IEEE/CANPS award for his contribution to a general detector simulation framework for nuclear and particle physics. He can be reached via e-mail at



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Leo Tilson's picture

I am often a little nervous when approaching a software package for the first time. This is exactly the sort of article to help me overcome my fears. From what I hear, ROOT is probably one of the most powerful databases out there - I am impressed for instance by the way in which the data can be highly compressed - but you also seem to have devoted a huge amount of effort into making it as user friendly as possible.

I have been reviewing my use of databases over the last few days because of some concern about MySQL, these concerns being prompted by the legal action being taken by Oracle against Google, and Oracle's reduction in support for OpenSolaris. I had never considered ROOT as an alternative to MySQL, until recently thinking of it as a rather specialised tool. I was pleased to note however that there are bindings for Ruby amongst other languages.

I wonder about your figures for OS shares? I have just installed ROOT, but instead of downloading it from its official site I have installed it from the Debian repository. If many people do this, then the numbers you record for Linux usage may underestimate its Linux usage.

Thank you.