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

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 ROOT in ALICE Online 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 2

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 Data Quality Monitoring 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 3

AMORE : Automatic MOnitoring Environment A DQM framework for the ALICE experiment The AMORE framework 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 4

Publisher – Subscriber paradigm Database used for the data pool Published objects are encapsulated into « MonitorObject » structure Design & Architecture 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 5

MonitorObjects 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 6 Dictionaries allow introspection in the client Standard ROOT interfaces  Easier for users, e.g. call Draw() blindly MOTObject allows embedding custom types

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 AMORE and ROOT 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 7

Detectors custom GUI  Expert view of the data their agent publishes User interfaces (1) 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 8

Generic User Interface  Based on TRootBrowser, custom TGListTree  TXMLEngine for layouts and preferences files User interfaces (2) 11/03/2013 9

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

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… Experience 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 11

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 Difficulties (1) 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 12

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 Difficulties (2) 11/03/

Code name « redemption » 1.No major new features 2.Fix the (base) classes inheritance and interfaces o Hopefully it can even be backward compatible 3.Make ROOT web friendly 4.Make ROOT looks nice o GUI and graphics need a modern look and feel o 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. My ideal ROOT 7 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 14

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 ! Conclusion 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 15

Backup slides 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 16

TMessage and objects evolution 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 17 Producer ROOT v. X Consumer ROOT v. Y>X TMes sage Datab ase Monitor Object Monitor Object Monitor Object Streamer Incompatible and no Streamer EnableSchemaEvolution doesn’t actually help. It only raises a flag in Tmessage that is used by TSocket

Web ROOT 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 18 An event (click) means a histo must be drawn An event (click) means a histo must be drawn 1.Get histo1 2.Use a special printer or method on the object 3.Send back the JSON or HTML5+JS or SVG+SMIL 1.Get histo1 2.Use a special printer or method on the object 3.Send back the JSON or HTML5+JS or SVG+SMIL myDiv.content = JSROOT.Draw(json) Another approach HTTP request (AJAX) Ask for data of histo1 JSON data HTML5+JS SVG+SMIL OR myDiv.content = data Server Client

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 Web ROOT 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 19

To be done in the JSON option:  Client o Optionally develop a facility js library to handle the request to server and the drawing in a div  Server / ROOT o Find the best way of generating JSON for any object (new Printer or addition method in TObject). If not defined fall back to an image ?  Client o Develop an efficient and complete histograming javascript library (drawing and manipulation). Usable without ROOT. Web ROOT 11/03/2013 Barthélémy von Haller & Adriana Telesca, ALICE, PH department, CERN 20