Use message routes and custom endpoints for device-to-cloud messages

  • Article
  • 02/10/2023

Note

Some of the features mentioned in this article, like cloud-to-device messaging, device twins, and device management, are only available in the standard tier of IoT Hub. For more information about the basic and standard/free IoT Hub tiers, see Choose the right IoT Hub tier for your solution.

IoT Hub Message Routing enables users to route device-to-cloud messages to service-facing endpoints. Routing also provides a querying capability to filter the data before routing it to the endpoints. Each routing query you configure has the following properties:

Property Description
Name The unique name that identifies the query.
Source The origin of the data stream to be acted upon. For example, device telemetry.
Condition The query expression for the routing query that is run against the message application properties, system properties, message body, device twin tags, and device twin properties to determine if it is a match for the endpoint. For more information about constructing a query, see the see message routing query syntax
Endpoint The name of the endpoint where IoT Hub sends messages that match the query. We recommend that you choose an endpoint in the same region as your IoT hub.

A single message may match the condition on multiple routing queries, in which case IoT Hub delivers the message to the endpoint associated with each matched query. IoT Hub also automatically deduplicates message delivery, so if a message matches multiple queries that have the same destination, it is only written once to that destination.

Endpoints and routing

An IoT hub has a default built-in endpoint. You can create custom endpoints to route messages to by linking other services in the subscriptions you own to the hub. IoT Hub currently supports Azure Storage containers, Event Hubs, Service Bus queues, and Service Bus topics as custom endpoints.

When you use routing and custom endpoints, messages are only delivered to the built-in endpoint if they don't match any query. To deliver messages to the built-in endpoint as well as to a custom endpoint, add a route that sends messages to the built-in events endpoint.

Note

  • IoT Hub only supports writing data to Azure Storage containers as blobs.
  • Service Bus queues and topics with Sessions or Duplicate Detection enabled are not supported as custom endpoints.
  • In the Azure portal, you can create custom routing endpoints only to Azure resources that are in the same subscription as your IoT hub. You can create custom endpoints for resources in other subscriptions by using either the Azure CLI or Azure Resource Manager.

For more information about creating custom endpoints in IoT Hub, see IoT Hub endpoints.

For more information about reading from custom endpoints, see:

Next steps