The new ALICE DQM client: a web access to ROOT-based objects

A Large Ion Collider Experiment (ALICE) is the heavy-ion detector designed to study the physics of strongly interacting matter and the quark-gluon plasma at the CERN Large Hadron Collider (LHC). The online Data Quality Monitoring (DQM) plays an essential role in the experiment operation by providing shifters with immediate feedback on the data being recorded in order to quickly identify and overcome problems. An immediate access to the DQM results is needed not only by shifters in the control room but also by detector experts worldwide. As a consequence, a new web application has been developed to dynamically display and manipulate the ROOT-based objects produced by the DQM system in a flexible and user friendly interface. The architecture and design of the tool, its main features and the technologies that were used, both on the server and the client side, are described. In particular, we detail how we took advantage of the most recent ROOT JavaScript I/O and web server library to give interactive access to ROOT objects stored in a database. We describe as well the use of modern web techniques and packages such as AJAX, DHTMLX and jQuery, which has been instrumental in the successful implementation of a reactive and efficient application. We finally present the resulting application and how code quality was ensured. We conclude with a roadmap for future technical and functional developments. 1. ALICE ALICE [1] is a general-purpose detector dedicated to the study of heavy-ion collisions at the CERN LHC. It is optimized to study the properties of the deconfined state of quarks and gluons produced in such collisions known as quark-gluon plasma [2]. It is also well-suited to study elementary collisions such as proton-proton and proton-nucleus interactions. Robust tracking and particle identification in a wide pT range are ensured by different types of detectors designed to cope with high particle multiplicities. The commissioning of the experiment was carried out during 2008 and 2009 in the underground experimental pit. Since the startup of the LHC in November 2009 and till the long shutdown in February 2013, the experiment has been successfully taking data, almost continuously. 21st International Conference on Computing in High Energy and Nuclear Physics (CHEP2015) IOP Publishing Journal of Physics: Conference Series 664 (2015) 062064 doi:10.1088/1742-6596/664/6/062064 Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1 Publisher Publisher Agents Publisher Publisher Clients Monitor Objects Pool Publish data Access data Notifications (DIM) 1010 0010 11 1010 0010 11 MonitorObjects