New Web Technologies for the LHCb Online Monitoring Displays

The LHCb Online Monitoring Displays is a web application, that gives access to real-time measurements and status information about the LHCb detector and its components, without the need to login. It is hosted at CERN on the computer lbcomet.cern.ch. The system is architecturally complex, based on the Comet technology for the data-transfer and the STOMP protocol for the communication between the clients and the message broker. The application is functional, however concerns are expressed over the future maintenance of the system’s architecture as is. The cause of these concerns are firstly the fact that the STOMP JavaScript client package is outdated and flagged by the original author flagged as non-maintained and secondly that todays modern browsers support real-time bi-directional communication which, at the time of development was not compatible even with some of the major browsers. Therefore, the objective of this project is to investigate modern data-push mechanisms, which could complement or replace the already applied technologies. Real-time data-transfer techniques are discussed and an open-source solution that could co-exist with the existing Apache ActiveMQ sever is presented. More specifically, the suggested solution includes the simplification of the system’s structure by subtracting the Orbited server, the replacement of XHR long-polling with WebSockets and to replace the STOMP protocol with the MQTT protocol. As far as the data interpretation on the client side is concerned, the Paho JavaScript library is recommended. The changes are implemented, with the student’s work focused on the front-end, and the result is functional. In addition, considering the increased use of mobile devices, recommendations for a modern and responsive view of the web application are made. The new design is partially implemented, founded on the latest version of the Bootstrap framework. Even though it is not fully developed, the result is satisfactory but of course, there is room for improvement.