问题
I am trying to understand Amazon AWS IoT and I see there is a Device Gateway connected between Sensors/Actuators and AWS (Rules Engine). I understand Sensors/Actuators are MQTT Clients which can Publish/Subscribe to the topics.
Device Gateway also supports Publish/Subscribe pattern is that means
Device Gateway is also a MQTT Client ?
Then where is the MQTT broker?
OR Device Gateway is Broker + communication interface to AWS-IoTservices?
I have attached an Image Amazon presentation on AWS IoT for the reference:
回答1:
The gateway is a MQTT broker, but not a fully compliant one. Some of the differences are:
- no retained message support
- no QOS2 support
- no message persistence
Full details can be found here http://docs.aws.amazon.com/iot/latest/developerguide/protocols.html
来源：https://stackoverflow.com/questions/34448185/is-aws-iot-device-gateway-an-mqtt-broker