Quality of Service Levels in Industrial IoT

This white paper discusses the Quality of Service (QoS) levels provided by the MQTT protocol in the context of Industrial Internet of Things (IIoT) applications. It outlines the three QoS levels: Level 0, which offers no delivery guarantees and can lead to message loss; Level 1, which ensures at least one delivery but may result in message duplication; and Level 2, which guarantees exactly one delivery but can introduce significant latency under load. The paper argues that these existing QoS levels are insufficient for the reliability required in IIoT systems, particularly in scenarios where timely and accurate data delivery is critical. It highlights the challenges associated with each QoS level, including the potential for catastrophic failures in industrial applications due to message loss or delays. The author advocates for a new standard that guarantees data consistency to better serve the needs of IIoT, emphasizing the importance of managing message queues and preserving event order to ensure data quality.