=Paper=
{{Paper
|id=Vol-3041/128-132-paper-23
|storemode=property
|title=Implementation of the Condition Database for the Experiments of the NICA Complex
|pdfUrl=https://ceur-ws.org/Vol-3041/128-132-paper-23.pdf
|volume=Vol-3041
|authors=Konstantin Gertsenberger,Alexander Chebotov,Peter Klimai,Igor Alexandrov,Evgeny Alexandrov,Irina Filozova,Andrey Moshkin
}}
==Implementation of the Condition Database for the Experiments of the NICA Complex==
https://ceur-ws.org/Vol-3041/128-132-paper-23.pdf
Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
IMPLEMENTATION OF THE CONDITION DATABASE
FOR THE EXPERIMENTS OF THE NICA COMPLEX
K.V. Gertsenberger1,a, A.I. Chebotov1, P.A. Klimai2, I.N. Alexandrov1,
E.I. Alexandrov1, I.A. Filozova1, A.A. Moshkin1
1
Joint Institute for Nuclear Research, 6 Joliot-Curie, Dubna, Moscow region, 141980, Russia
2
Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow
region, 141701, Russia
E-mail: a gertsen@jinr.ru
The processing and analysis of experimental and simulated data are an integral part of all modern
high-energy physics experiments. These tasks are of particular importance in the experiments of the
NICA project at the Joint Institute for Nuclear Research due to the high interaction rate and large
particle multiplicity of ion collision events, therefore, the task of automating the considered processes
for the NICA complex has particular relevance. The paper describes a new information system based
on the Condition Database, as well as related services to automate storing, managing, searching and
using various parameters and operation modes of the on-going and future NICA experiments for
experimental and simulated data processing. The implemented system provides the necessary
information for event processing and physics analysis tasks, and organises the transparent, unified
access to and management of the required parameter data in scientific research. The scheme and
purposes of the Condition Database, its attributes, key aspects of the development are described. In
addition, a common deployment system of the developed database and related services for the NICA
experiments is noted.
Keywords: condition database, NICA experiments, event data processing, information
system, web services
Konstantin Gertsenberger, Alexander Chebotov, Peter Klimai, Igor Alexandrov,
Evgeny Alexandrov, Irina Filozova, Andrey Moshkin
Copyright © 2021 for this paper by its authors.
Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
1. Introduction
According to the program of the Joint Institute for Nuclear Research (JINR, Dubna) for the
study of heavy ion collisions, the construction of the NICA (Nuclotron-based Ion Collider fAcility)
accelerator complex [1] will be completed in the coming years to collide particles in the range of
atomic masses A = 1–197 at energies in the center-of-mass system up to 11 GeV for gold ions and up
to 27 GeV for protons. There are two points of particle interactions in the storage rings of the NICA
collider, where each interaction point will have a detector oriented to its own physics research
program, namely, MultiPurpose Detector (MPD) and Spin Physics Detector (SPD). The MPD detector
is optimized for a comprehensive study of the properties of hot and dense baryonic matter produced in
heavy ion collisions and search for a critical point of phase transitions. Spin Physics Detector is aimed
at studying the spin structure of nucleons in high-intensity polarized beams of light nuclei.
Furthermore, one of the main elements of the first stage of the NICA project is an experiment on a
fixed target, i.e. BM@N (Baryonic Matter at Nuclotron), which is carried out on particle beams
extracted from the Nuclotron into the experimental hall, and whose technical runs have been
conducted since 2015.
Modern large scientific research, such as the NICA experiments, is characterized by long
duration, high labor intensity, complexity, and processing a large amount of data obtained during the
experiment. In this regard, the task of automating the processes of collecting, storing, processing and
analysing experimental and simulated data of the NICA complex acquires particular relevance. The
automation of modern particle collision experiments is impossible without the use of specialized
information and computing systems, which allow collecting, storing and processing event data,
managing the experiment during runs, simultaneously servicing a large number of data requests and
performing other actions being necessary to obtain high-quality physics results. Databases of various
purposes and information services related to their use and support are an integral part of such software
for online and offline data processing in experiments.
At present, large high-energy physics experiments are not employed without the creation and
use of automated information systems, therefore, within the framework of the RFBR grant 18-02-
40125, a complex of information systems for online and offline data processing, including a database
of operation conditions and states of experimental systems (hereinafter the Condition Database), is
developed for the NICA experiments. The next section presents general information on the
architecture of the developed system and key aspects of its implementation.
2. Development of the Condition Database for the NICA experiments
Information systems built on top of modern databases and offering various user services for
the transparent access to and management of stored information on the experiment are an important
part of not only online, but also offline data flow tasks of experiments, including the processing and
analysis of obtained physics data. One of such widely used software systems, the condition database,
is aimed at storing, managing and using various parameters and operation modes of detectors and
experimental subsystems for online and offline data processing, including algorithms for the
reconstruction and physics analyses of particle collision events. The corresponding information system
also solves problems of the convenient access to and control of the required parameters of the facility
operation to employ them at all stages of experimental and simulated event processing.
The Condition Database for the NICA experiments (also called Unified Database) has been
developed as a central storage of information on the operation conditions of various systems, as well
as the parameters of the experiment being conducted or simulated. These data are necessary for the
reconstruction and analysis of the recorded collision events, detector simulation, and are a key element
at the stage of processing the obtained data. The implemented database provides the management of
stored data and unified access to them for online and offline data processing systems, ensuring correct
multi-user processing, actuality, integrity and consistency of the information. Furthermore, the
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
automatic regular backup of the stored data ensures recoverability in the case of software or hardware
malfunctions.
The development of the Condition Database has been carried out on the PostgreSQL relational
database management system. In the designed architecture of the database [2], three component parts
can be emphasized: storing information on the conducted experiment runs and corresponding
experimental data files, on generated simulation files, and storing the parameters of arbitrary formats
for the subsystems of the experiment. During the design, the structure of the database was simplified
as much as possible and unified to have a general scheme that can be used in various physics
experiments on particle collisions, in particular, the NICA experiments. The following groups of the
parameters stored in the Condition Database can be highlighted: configuration data concerned with the
operation modes of the experiment systems, for example, programmable parameters for electronics,
calibration data describing the calibration and alignment of the subdetectors, parameter data presenting
the states of the detector systems and algorithm data that specify the way algorithms process events,
for instance, cuts for the selection of particle tracks.
An important property of the parameters stored in condition databases is their changing during
runs of experiments [3]. A single value or a set of values for a parameter describes the state of the
system for a limited period of time and is used only for analysing events received in this interval of
operation. In this regard, the stored parameters are characterized by their validity interval. As a result,
the validity of parameters is usually defined as a time period or a run interval, and the corresponding
time value or run number is used as a key to retrieve the parameter. In the developed Condition
Database, the validity of parameters is determined by the run interval, for which they are valid.
Furthermore, parameter values are retained in the case of updating (called historical preservation),
which allows one to repeat event data processing with outdated parameter values used in the past. In
addition, a key feature of the database is that the developed architecture provides storing parameters of
any predefined types in the form of a binary object serialized to one database field through a
programming interface.
3. Application programming and user interfaces for the Condition Database
To use the parameters stored in the Condition Database for event data processing of the NICA
experiments, two application programming interfaces (API) have been developed. The first one, REST
API service, provides users and other systems with an HTTP format of requests to search, manage and
use information stored in the database. The REST interface allows querying and responding to GET,
PUT, POST and DELETE commands, which refers to the reading and searching, updating, creating
and deleting of operations concerning the parameters required for experimental or simulated data
processing. The implemented REST API service has been deployed on the NICA cluster and provides
a special URL as a REST endpoint. The second API is an accustomed C++ interface for integrating the
Condition Database with the software frameworks of the NICA experiments, which are all based on
the CERN ROOT package [4], for using stored information in online and offline data processing. The
C++ interface allows accessing and managing necessary condition data as attributes of the objects in
the experiment software.
In addition, a user-friendly web service for the Condition Database has been developed to
simplify viewing, searching and managing information on the experiments by collaboration members
via a web browser. It provides the following features depending on the role of the authenticated user:
convenient viewing, adding or changing information on the experiment in a tabular view, multi-
column sorting and data filtering, easy searching for necessary parameters according to specified
criteria, visualizing summary information on stored data and many other functions. Figure 1 shows the
deployed web service of the Condition Database for the BM@N experiment. After authorization, users
can add and modify records directly from their web browser. It is crucial that the implemented web
service has a configurable view, so it is easily adjusted to use in any NICA experiment.
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
Figure 1. Home page of the web service for the Condition Database of the BM@N experiment
4. Information System based on the Condition Database
Information on experiment runs, on obtained experimental and simulated files, as well as
various conditions and parameters of the system operation, is recorded to the Condition Database both
in an online and offline mode. Then the stored information is used in developed algorithms for
processing event data of the NICA experiments, including simulation, raw data digitization, the
reconstruction of the obtained particle collision events and their further physics analyses.
Experimental and simulated data processing is performed on distributed computing systems of the
NICA project via experiment frameworks, which access and use the required parameters through the
implemented APIs.
The Condition Database is being constantly improved via the development of various
additional services. To have only one account for all the information systems of the experiments,
FreeIPA authentication has been added. Once a collaboration member has registered an account, the
member can use the login to sign in to all the information systems, including the web service of the
Condition Database. The FreeIPA system provides centralized authentication, authorization and
account information by storing data about collaboration members, their groups and other objects being
necessary to manage security aspects. Three groups for administrators (full access), editors (e.g.,
detector team) and readers (regular users) have been created in the FreeIPA system to restrict user
access to the Condition Database.
It is important to monitor the state of the information systems in order to minimize the
response time in the case of failures being especially critical during experiment runs. The Monitoring
Service has been developed for the information system, it tracks server hosts and the Condition
Database, stores their state parameters and visualizes them through the Grafana system on a special
web site. In the case of any malfunctions, the Monitoring Service sends notifications to given emails
of responsible people.
The Condition Database is in demand for all the NICA experiments, so the information system
was made generic and highly customizable. A Configuration and Deployment System has been
implemented for convenient installation for any NICA experiment. The main concept of the common
deployment system was to develop a unified procedure for configuration and installation steps on
deploying all the components of the Condition Database and related information services. It uses
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
Docker containers and shell scripts, which allows installing the database, web service, REST API and
other components for the experiments of the NICA project, taking into account some specifics of the
experiments. The result of the configurable deployment of the information system for the NICA
experiments is the created database and services, including the web service deployed on the host, thus
collaboration members can immediately start to work with the Condition Database.
5. Conclusion
The Condition Database implemented on PostgreSQL 12 is an important component of the
complex of information systems for the NICA experiments. It provides a centralized storage of the
necessary conditions and parameters and ensures unified access to them for online and offline
experimental systems to process and analyse data from the facilities of the NICA complex, as well as
allows collaboration members to manage up-to-date information on the experiments. The Condition
Database has been deployed on the NICA cluster, and at present, it is actively used in distributed data
processing of the BM@N experiment, the first experiment of the NICA project. The REST API
service and ROOT C++ interface have been implemented to use information stored in the Condition
Database for processing simulated and experimental data in other software systems of the experiments.
The web service, single authorization and monitoring systems have been developed to simplify
viewing and managing information on the experiments by collaboration members over the Web. The
Common Deployment System and additional services have been implemented to install the Condition
Database for all the experiments of the NICA project, taking into account some specifics of the
experiments. The information system makes a significant contribution to solving the problem of
automating the acquisition, storage, processing and analysis of obtained data, and is also a necessary
element for obtaining timely high-quality physics results.
6. Acknowledgement
The reported work was funded by the Russian Foundation for Basic Research (RFBR)
according to the research project No.18-02-40125.
References
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10.09.2021)
[2] Gertsenberger K., Chebotov A., Alexandrov I., Filozova I., Alexandrov E. Design of the
Condition Database for online and offline data processing in experimental setups of the NICA
complex // Izvestiya SFedU. Engineering Sciences. 2020. No. 7 (217). pp. 172-180.
[3] Laycock P., Dykstra D., Formica A., Govi G., Pfeiffer A., Roe S. and Sipos R. A Conditions Data
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