AWS IoT provides several connectivity models to enable IoT devices to establish their connection. Currently, AWS IoT offers the following protocols:

• Message Queuing Telemetry Transport (MQTT)
• Hypertext Transfer Protocol (HTTP)
• MQTT over Websocket 

We can build a connectivity model between IoT devices and the AWS IoT backend. We can categorize the IoT device platform into the following three models based on their supported connectivity:

• For an IoT device with network capabilities, if this device has all the support required by AWS IoT, then this device can access AWS IoT directly.
• The second connectivity model is to build a connection to AWS IoT through a gateway. This approach is applied for an IoT device that has network capabilities which are not supported for AWS IoT protocols.
• The last approach is to be applied to IoT devices that do not have network capabilities. We should attach these devices to a network device, such as Raspberry Pi, BeagleBone, and a computer that works as a bridge between the device and AWS IoT.