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After the gateway connects to ClearBlade IoT Core over the MQTT bridge, it can send or receive three types of messages:
Control messages: Attaches a device to the gateway or detaches a device from the gateway. These messages are sent between the gateway and ClearBlade IoT Core. ClearBlade IoT Core accepts control messages only from gateways; if another type of device attempts to send a control message, ClearBlade IoT Core closes the connection.
Messages from gateways and devices: Can be relayed by the gateway on behalf of a device or sent directly from the gateway.
System error messages: When the gateway is subscribed to the MQTT system error topic on behalf of the device, ClearBlade IoT Core sends error messages whenever the device encounters an error.
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If you configured the gateway to authenticate devices using the devices' JWTs, the attach message’s payload must include the token in JSON format: { "authorization" : "{JWT_token}" }. Otherwise, ClearBlade IoT Core authenticates the device by checking its gateway’s association with the gateway.
Success response
After the device is authorized, ClearBlade IoT Core sends a PUBACK message to the gateway in response to the attach message. After the gateway receives the PUBACK message, it can publish and subscribe to ClearBlade IoT Core topics on behalf of the device, such as telemetry or configuration messages.
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