Starting today, AWS IoT Core customers can configure the quality of service (QoS) when publishing messages via the republish action of a topic rule. AWS IoT Core supports QoS levels 0 and 1 for MQTT messages, where QoS 0 means a message is delivered zero or more times and QoS 1 means message is delivered one or more times. See AWS IoT MQTT documentation for more details about AWS IoT QoS definition.