Direct methods support in the IoT Hub Connected Service

The Visual Studio 2017 Connected Service for Azure IoT Hub has received an update a couple of months ago.

This update had some visual updates and now supports a Singleton pattern for the Device client too.

But it also included support for both Device twins and  Direct Methods. The latter feature looks a lot like the Commands method but there are some fundamental changes.

Yes, both solutions (Command and Direct Method) can execute code on a remote IoT Hub client. But the remote method just passes a message to the client. The Direct method can pass a message in a certain context. It calls a specific method (a client can have multiple methods registered) and passes the JSON parameter.

If you execute a Command, it feels like fire-and-forget. There is no descriptive response. But the caller of a Direct Method can wait until a response is accepted and a JSON value is returned.

Let’s check out Direct Methods.

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Combining Azure StreamAnalytics with Azure Function Sink

There are many ways to collect data from an IoTHub and pass it through Azure Functions:

• Trigger an Azure Function directly by the IoTHub events or operations monitoring
• Trigger an Azure Function using an EventHub or message bus as endpoints of IoTHub routing
• Trigger an Azure Function using an EventHub as output sink of a Stream Analytics job

All these solutions serve their own purpose.

But the last one, using an EventHub, can be pretty annoying. Yes, this is a great way if you will use the security policies and/or consumer groups of the Eventhub. But otherwise, there is a lot of administration.

Let’s check out how life is becoming much easier with a new Azure functionality which is still in public preview called Azure Function Sink.