Is AWS IoT Device Gateway an MQTT broker?

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