1. ROOT Support and Developments at FNAL
ROOT For RUN II
ROOT Support and Developments at FNAL
Philippe Canal
7/10/2019

2. Philippe Canal, pcanal@fnal.gov
ROOT for Run II
Selecting a Physics Analysis Tool
Concerns
Addressing the Concerns
7/10/2019
Philippe Canal,

3. Philippe Canal, pcanal@fnal.gov
Requirements
Functional requirements
Scripting language
Run on several platforms
Modular architecture
Support requirements
Portability
Ease of maintenance
Close collaboration
Committees to understand requirements and support needs.
Composition of the committees: Blend of physicist and computer professionals.
7/10/2019
Philippe Canal,

4. Philippe Canal, pcanal@fnal.gov
Candidates
Histoscope
No scripting language
LHC++
Scheduled for use in 2005 – too late
IDL
Limitation on the size of the data set
Root
Closest to meeting the requirements
Some requirements were only partially met - risky
7/10/2019
Philippe Canal,

5. Philippe Canal, pcanal@fnal.gov
A Visit to CERN
Discuss issues
(Some resolved on the spot)
ROOT team is enthusiastic to collaborate
Plans to hold a ROOT workshop at FNAL for US HENP experiments considering ROOT
7/10/2019
Philippe Canal,

6. Requests From The Workshop
Improved robustness
STL support
Improved documentation
Persistence for CLHEP
Multi-threading
Interface to SQL
7/10/2019
Philippe Canal,

7. Philippe Canal, pcanal@fnal.gov
Improved Robustness
External preprocessor
FNAL ROOT team modified CINT and ROOT to implement this.
Modularization of ROOT
Implemented by ROOT team in v2_23
Automatic handling of STL
Added by the ROOT team
Available via the script compiler
7/10/2019
Philippe Canal,

8. Philippe Canal, pcanal@fnal.gov
Improved Robustness
User support, deployment, and testing
UPS/UPD
Test on all released platforms
Local support
Central contact to voice user needs and during feature implementation
7/10/2019
Philippe Canal,

9. Philippe Canal, pcanal@fnal.gov
Script Compiler
Advantages
Five Times Faster than Interpreter
Full C++ capability
Syntax checking
Can be used to add a class to a ROOT session.
Disadvantages
Can only load a C++ library once
Compile time
The Script Compiler gives the ROOT user the choice to compile a ROOT macro rather than using CINT and interpreting it. The Script Compiler compiles a ROOT macro and produces a shared library.
The compiler and compiler switches used by default are the same as those used to build the current root executable (the one from which the script compiler is invoked). These default values can be easily changed.
We will show you two demonstrations. In the first demonstration, we will show you how to invoke the script compile, and illustrate the difference in execution speed between the interpreted run and the compiled run. In the second demonstration, I will show you how you can add a class to root session by using the script compiler.
cd script
root –l
gROOT->Time()
.L ScriptCompilerDemo.C++
.files note the shared library
Demo()
note the time it takes .q
root -l
.L ScriptCompilerDemo.C
Note the time it takes
7/10/2019
Philippe Canal,

10. Adding a Class with The Script Compiler
Step 1: Write the class definition in a separate file.
Step 2: Add the ClassDef and ClassImp macro calls to the class definition.
Step 3: Load the class with the script compiler.
root[0] .L ABCClass.C++ root[1] ABC abc root[2] abc.a = 3.2; root[3] abc.b = 4.0; root[4] abc.Dump();
Step 1: Open the /v1/home/pcanal/root/script/ABCClass.C file.
The class ABC is defined. Note the ClassDef and ClassImp.
#include "TObject.h"
// define the ABC class and make it inherit from
// TObject so that we can write ABC to a root file
class ABC : public TObject {
public:
Float_t a,b,c,p;
ABC():a(0),b(0),c(0),p(0){};
// Define the class for the cint dictionary
ClassDef(ABC,1) };
// Call the ClassImp macro to give the ABC class RTTI and
// full I/O capabilities.
#if !defined(__CINT__)
ClassImp(ABC);
#endif
Then execute the following commands:
.L ABCClass.C++
.files note the shared library ABCClass
ABC abc abc.a = 3.2; abc.b = 4.0; abc.Dump();
7/10/2019
Philippe Canal,

11. Improved Documentation
For the novice user
Root 101 hands-on class with exercises
Root files and GUI overview
Tree viewer
How to find more information
Macros
“Getting started with root” document
7/10/2019
Philippe Canal,

12. Improved Documentation
For the intermediate user
Root 102 hands-on class with exercises
Functions and fitting
Building root trees
Putting trees to work
More about CINT
Script complier
C++ basics for root users document
Extras
Collections slide presentation
XClasses implementation in ROOT
7/10/2019
Philippe Canal,

13. Philippe Canal, pcanal@fnal.gov
And …
Interface to CLHEP
PhysicsVector
More to come
Multi-threading
Implemented by GSI
Interface to SQL
Implemented by the CERN ROOT team
7/10/2019
Philippe Canal,

14. Other FNAL/ROOT Projects
Automatic documentation
Inline functions
Point and click inheritance diagram
Self describing object format
Reading ROOT files without having the source file for the saved object.
7/10/2019
Philippe Canal,

15. Philippe Canal, pcanal@fnal.gov
Conclusion
Confidence in our choice of ROOT
Successfully addressed concerns
Success factors
Unprecedented support by ROOT team
Make up of skills and personalities of the FNAL ROOT team
Identification of specific issues to work on
7/10/2019
Philippe Canal,