The Online Software of JUNO Data Acquisition System

The Jiangmen Underground Neutrino Observatory (JUNO) is the new generation large liquid scintillator neutrino experiment. Its goals are to measure the neutrino mass ordering and neutrino mixing parameters with high precision. The data acquisition (DAQ) system consists of data flow software and online software. In order to meet requirements for the JUNO experiment, the data flow software runs on a computing cluster consisting of hundreds of servers to perform online data processing. And the online software, designed to provide service and management for the distributed cluster, manages hundreds of data flow processes and monitors their running status. In addition, in order to detect possible interactions of supernova neutrinos, the online software is required to have a very high duty cycle and high availability. This software provides configuration, control, information sharing, and high availability services for the DAQ. It employs a microservice architecture to reduce coupling between modules. It also utilizes a container management mechanism based on Kubernetes to optimize software deployment and failover, providing more reliable and long software lifecycle support for the JUNO. The online software made a new attempt using new technologies, providing a concept for a high-availability service framework suitable for large-scale experiments.