Online Database Access Application for the CMS DAQ System in the High Luminosity LHC

In large-scale experiments like the Compact Muon Solenoid (CMS) at CERN, dynamic and automated system configuration, along with continuous monitoring, is critical for successful data collection. Monitoring and exception data are stored in a database to support future analysis and issue prevention. This process is managed by the TStore service, which provides a SOAP interface to facilitate communication between the DAQ applications and the monitoring system. Within the XDAQ framework used for the CMS experiment, TStore serves as a proxy, facilitating client interactions with Oracle databases while offering advantages over direct connections. An analysis of the CMS subsystems revealed that 9 out of 13 primary systems use TStore either directly or indirectly. However, TStore was not initially migrated to the latest version of XDAQ due to incompatibilities between the OCCI (Oracle C++ Call Interface) library and C++17 on AlmaLinux 9. After several years of being unmaintained, a new OCCI version has been released, making TStore compatible with the upgraded environment. The report discusses the task of upgrading TStore and ensuring its functionality through testing. To modernize the system, a new REST API structure was designed, replacing the SOAP API. This hierarchical REST architecture simplifies data management, standardizes request handling, and improves usability by leveraging widely adopted specifications.