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Enhancing Data Quality Monitoring in ALICE Using ROOT: Challenges and Future Directions

This presentation discusses the experiences and limitations of using ROOT software within the ALICE experiment at CERN, focusing on Data Quality Monitoring (DQM). It highlights the features of the AMORE framework for online data analysis and visualization, along with a review of existing challenges such as web compatibility, user interface complexities, and data management issues. The presentation advocates for improvements in ROOT's architecture, user experience, and community support, aiming to develop a more efficient and user-friendly environment for data analysis in high-energy physics.

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Enhancing Data Quality Monitoring in ALICE Using ROOT: Challenges and Future Directions

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  1. The ALICE DQM Software and ROOT Experiences, limitations and suggested improvements ROOT Users Workshop Barthelemy von Haller & Adriana Telesca for the ALICE DAQ Collaboration

  2. ROOT in ALICE Online • ALICE : A Large Ion Collider Experiment • 18 detectors • Trigger rate : 10 KHz (max) • Bandwidth to mass storage : 1.25 GB/s • Online usage of ROOT • « ROOTification » • Detector algorithms • Data Quality Monitoring Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  3. Data Quality Monitoring • Online feedback on the quality of data • Make sure to take and record high quality data • Identify and solve problem(s) early • Data Quality Monitoring (DQM) involves • Online gathering of data • Analysis by user-defined algorithm • Storage of monitoring data • Visualization Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  4. The AMORE framework • AMORE : Automatic MOnitoring Environment • A DQM framework for the ALICE experiment Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  5. Design & Architecture • Publisher – Subscriber paradigm • Database used for the data pool • Published objects are encapsulated into « MonitorObject » structure Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  6. MonitorObjects • Dictionaries allow introspection in the client • Standard ROOT interfaces • Easier for users, e.g. call Draw() blindly • MOTObject allows embedding custom types Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  7. AMORE and ROOT • Data pool implemented as a database • TMessage used to serialize MonitorObjects • TMySQLServer et al. • Plugin architecture using ROOT reflection • Modules are dynamic libraries loaded at runtime • Custom and generic GUI (see next slides) • Macro for quick post-processing without releasing new version of a module Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  8. User interfaces (1) • Detectors custom GUI • Expert view of the data their agent publishes Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  9. User interfaces (2) • Generic User Interface • Based on TRootBrowser, custom TGListTree • TXMLEngine for layouts and preferences files

  10. Web access • Web access to images of the plots via the ALICE eLogbook Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  11. Experience • ROOT provided key features • C++ database interface • Plugin mechanism • GUI • Macros • XML • We could have done the same with a palette of tools, here we got it all at once • Quick, kind and effective support • Still, anything can always be improved… Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  12. Difficulties (1) • ROOT not web friendly (Bertrand gives us hope!) • View and manipulate ROOT objects like in a TCanvas/GUI • Others are working on solutions, lack of concertations ? • Axes are not easy to manipulate • Responsibilities are unclear (histo, pad, axis) • Time-based axes should be far easier to use • Objects ownership • E.g. TH1 with « functions » encapsulated in a MOTObject • E.g. THStack (main histo is destroyed, not the others) • CMake: missing FindROOT.cmake or ROOTConfig.cmake • Using ROOT as a simple library (no TApplication) • We want our core files and stack traces Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  13. Difficulties (2) • Histograms hierarchy is wrong • Sometimes obscure or inconsistent class interfaces • E.g. TMessage::EnableSchemaEvolution() does actually nothing if not used in conjunction with TSocket • E.g. Zoom is a property of TH1 != draw option and log scale are properties of TPad • GUI: powerful but writing them is tough, error prone and pretty verbose • Support • Too often the answer is « Why don’t you do it this way? » instead of fixing the issue • C++ standard or ROOT standard ? • STL, Boost, Collections and types

  14. My ideal ROOT 7 Code name « redemption » • No major new features • Fix the (base) classes inheritance and interfaces • Hopefully it can even be backward compatible • Make ROOT web friendly • Make ROOT looks nice • GUI and graphics need a modern look and feel • Simplify GUI programming while you are at it Prepare ROOT for the next 20 years and protect future users from mistakes made 20 years ago. Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  15. Conclusion • The ALICE DQM uses and relies on many features of ROOT • ROOT provided a very complete toolbox which helped us develop effectively AMORE • ROOT is going to be used for many more years and, today, there is an opportunity to fix long-standing issues • Thank you for all the good work ! Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  16. Backup slides Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  17. TMessage and objects evolution Producer ROOT v. X EnableSchemaEvolution doesn’tactually help.It onlyraises a flag in Tmessagethatisused by TSocket Monitor Object Streamer Incompatible and no Streamer Monitor Object MonitorObject Consumer ROOT v. Y>X Database TMessage EnableSchemaEvolution Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  18. Web ROOT Anotherapproach Client Server An event (click) means a histo must bedrawn HTTP request (AJAX) Ask for data of histo1 Get histo1 Use a special printer or method on the object Send back the JSON or HTML5+JS or SVG+SMIL myDiv.content = JSROOT.Draw(json) JSON data OR myDiv.content = data HTML5+JS SVG+SMIL Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  19. Web ROOT • JSON : close to what BB is doing, still people can easily use the js lib alone. • Need for a performant and complete histograming JS library • Adding DrawWeb() to classes seems a reasonably important effort (?) • Creating a specific printer might even be simpler • If no printer/method available for a certain type, simply degrade to generate an image. • HTML or SWIG is lighter for the client but today clients (browsers) are powerful Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

  20. Web ROOT • To bedone in the JSON option: • Client • Optionallydevelop a facilityjslibrary to handle the request to server and the drawing in a div • Server / ROOT • Find the best way of generating JSON for anyobject (new Printer or addition method in TObject). If not definedfall back to an image ? • Client • Develop an efficient and completehistogramingjavascriptlibrary (drawing and manipulation). Usable withoutROOT. Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN

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