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Event Schema for MQTT Routed Messages

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MQTT Messages are routed to an Event Grid topic as CloudEvents according to the following logic:

For MQTT v3 messages or MQTT v5 messages of a payload format indicator=0, the payload will be forwarded in the data_base64 object and encoded as a base 64 string according to the following schema sample.

{
	"specversion": "1.0",
	"id": "9aeb0fdf-c01e-0131-0922-9eb54906e20", // unique id stamped by the service.
	"time": "2019-11-18T15:13:39.4589254Z", // timestamp when the message was received by the service.
	"type": "MQTT.EventPublished", // set type for all MQTT messages enveloped by the service.
	"source": "testnamespace", // namespace name
	"subject": "campus/buildings/building17", // topic of the MQTT publish request.
	"data_base64": 
    {
		IlRlbXAiOiAiNzAiLAoiaHVtaWRpdHkiOiAiNDAiCg==
	}
}

For MQTT v5 messages of content type= “application/json; charset=utf-8” or of a payload format indicator=1, the payload will be forwarded in the data object, and the message will be serialized as a JSON (or a JSON string if the payload isn't a JSON). Setting the content type and/or the payload format indicator enables you to filter on your payload properties as the payload is forwarded within the data field as is. Learn more about filtering on the message's payload.

{
	"specversion": "1.0",
	"id": "9aeb0fdf-c01e-0131-0922-9eb54906e20", // unique id stamped by the service.
	"time": "2019-11-18T15:13:39.4589254Z", // timestamp when the message was received by the service.
	"type": "MQTT.EventPublished", // set type for all MQTT messages enveloped by the service.
	"source": "testnamespace", // namespace name
	"subject": "campus/buildings/building17", // topic of the MQTT publish request. 
	"data": 
    {
		"Temp": 70,
		"humidity": 40
	}
}

For MQTT v5 messages that are already enveloped in a CloudEvent according to the MQTT Protocol Binding for CloudEvents whether using the binary content mode or the structured content mode in JSON encoding (utf-8), the event will be forwarded with the original default CloudEvents attributes after enrichments according to the following schema sample.

{
	"specverion": "1.0",
	"id": "9aeb0fdf-c01e-0131-0922-9eb54906e20", // original id stamped by the client. 
	"time": "2019-11-18T15:13:39.4589254Z", // timestamp when the message was received by the client
	"type": "Custom.Type", // original type value stamped by the client.
	"source": "Custom.Source", // original source value stamped by the client.
	"subject": " Custom.Subject", // original subjectvalue stamped by the client.
	"data": 
    {
		"Temp": "70",
		"humidity": "40"
	}
}

Next steps:

Use the following articles to learn more about routing:

QuickStart:

Concepts: