1. ROOT Event Recording system
Katerina Opocenska,
CERN PH-SFT Summer student 2008
[1/7/2008 – 12/9/2008]
Supervisor: Bertrand Bellenot
26th August 2008

2. Project motivation & goals
To record and replay events in ROOT
Commandline events
Commands typed by user ("new TBrowser();")
GUI events
Window creation, resize, movement
Mouse movement, (double)click, drag&drop …
Why?
QA purposes (especially ROOT GUI)
Presentations, tutorials
To avoid performing the same operations manually again and again
Create once and then just replay
Like macros in Excel

3. How it works – overview Recorder implemented as standalone ROOT script
recorder.C
Only few lines of code added to ROOT sources
Interface for recorder: TRecorder.h
Using of signal-slot communication mechanism
Recorded events stored in TFile
All events from 1 recording session stored in 1 TFile
Stored in TTree data structure
Recorder runs both on Linux and Windows
Platform-specific solutions developed for replaying of windows moving

4. Recording Start ROOT Run recorder: .L recorder.C+
Prefarably with no windows
Run recorder: .L recorder.C+
recorder();
Push ● button to start recording
In "Save As" dialog enter name for log file
Work with ROOT freely
Issue commandline commands
Work with GUI
Press stop button on recorder to stop recording
Interactive demo

5. Replaying Run recorder: .L recorder.C+ Push ► button to start
In "Open" dialog choose
ROOT file with previously recorded events
Watch the replaying
Mouse cursor is used when replaying
When replaying finishes, it is written to the console
Interactive demo

6. Recording & replaying - notes
In fact: replaying = state recreation
All the objects are created again
Replaying events = executing them on real (recreated) objects
Same setup needed for recording and replaying
Just the execution of static code is recorded,
not the code itself
If you record command ".x path/script.C" and you want to replay it, this script must be present in the same place also in time of replaying
State capturing is part of recording
If you want to replay events for some window, creation of this window must be also recorded
Create window
Start recording
Work with window
Start recording
Create window
Work with window

7. C++ (non-GUI) interface for Recorder
class TEventRecorder : public TRecorder {
public:
// Recording
void Start(const char * filename, Option_t * option="RECREATE");
void Stop();
// Replaying
bool Replay(const char * filename);
void Pause();
void Resume();
void ReplayStop();
// Listing
void List(const char * filename);
void ListGui(const char * filename); } …

8. Conclusion Major part of project has been already done
My plan for the next 2,5 weeks:
Implementing additional requests 
Testing and fixing minor bugs
Developing better GUI for recorder
Improving current code
smoother cursor and windows movement
optimalization of performance
Code comments
User and programmer documentation