Concurrent experimentation in NCSLab: A scalable approach for online laboratories

The scheduling of user access to test rigs is vital for online laboratories, as a good access scheduling scheme can reduce waiting time and improve the utilization of experimentation systems. To enhance the benefits of online laboratories and also improve user experience, a novel system that is constructed based on front-end and back-end separation has been explored in this paper, which is scalable with a complex four-tier architecture supporting both remote and virtual experiments. A concurrent scheme that allows many users to conduct real-time interactive experiments with a single test rig has been implemented. The new system enables massive access for virtual experimentation and saves users from booking sessions in advance or queuing. To verify the effectiveness of the system, a renewable energy system has been developed, thus, users can concurrently conduct experiments with different control algorithms and monitoring interfaces for research and education purposes. A scalability test was conducted, the results of which showed that 94.67% of 300 users can concurrently access the same virtual laboratory, proving the scalability and concurrency features of the proposed system. The system demonstrated a throughput of 499.4 requests per second without errors during a 30-second performance test with 1600 concurrent users, where each user established 10 connections. & COPY; 2023 Published by Elsevier B.V.