This repository contains the code for the CaseOnline.Azure.WebJobs.Extensions.Mqtt NuGet Package. This package enables you to trigger an Azure Function based on a MQTT Subscription. By binding a MqttTrigger attribute as an input parameter for your function, you'll receive messages of type PublishedMqttMessage. Internally this is wired up using MQTTnet.

• Create an Azure Function using Visual Studio or using Visual Studio Code

• Make sure your Microsoft.NET.Sdk.Functions package version is 1.0.7 or higher

• Install the CaseOnline.Azure.WebJobs.Extensions.Mqtt NuGet package in you Functions Project

• Add the Mqtt server settings to your 'local.settings.json' during development time or to your appsettings when running on Azure:

  • MqttServer (just the dns/hostname)
  • MqttUsername
  • MqttPassword
  • MqttPort (optional, defaults to 1883)
  • MqttClientId (optional, defaults to a random Guid)

• When deploying/running on Azure set/ad the application-setting FUNCTIONS_EXTENSION_VERSION to beta

• Add a MqttTrigger attribute to your function parameters:

  public static void MyFunction([MqttTrigger(new[] { "my/mqtt/topic" })]PublishedMqttMessage message) 
  

• Deploy / Run your function. Azure function will subscripe to the Mqtt server/topic(s) and trigger your function when messages get published

The code currently works as it is but I have to make it better configurable before I publish it as a NuGet Package. Things that have to be done:

• Have more beta-testers running/using it (please help! 😇)
• Create more Unit Tests & Integration tests and get code coverage to >80%
• Use ILogger instead of TraceWriter which currently does not output on dev machine for some reason?
• Create demos for integrations with CloudMqtt.net and Azure IoT Hub

Expect a 1.0.0 version of the NuGet package in April '18.

Internally the MQTTnet is used for the Mqtt implementation. For complexer configurations, for example if you want to

• use Tls
• pecial certificates
• custom logic for setting the topics/clientId
• connecting over websockets
• control the QoS level per topic

To do this, implemented a custom ICreateMqttConfig and provide this Type as parameter to the MqttTrigger like this:

public static void MyFunction([MqttTrigger(typeof(MyMqttConfigProvider))]PublishedMqttMessage message)

In your implementation of ICreateMqttConfig you need to return an instance of abstract class MqttConfig which requires you to implement a property of type IManagedMqttClientOptions. Examples on how to build an instance of IManagedMqttClientOptions are available in the ManagedClient wiki of MQTTnet.

An example of this custom client configuration is implemented in this function.

Please find some samples here in the sample project. The simple example subscribes to a topic where Owntracks publishes location information.

• MQTTnet

• 1.0.0 Initial release, april 2018
• 1.5.0 Output binding for publishing MQTT messages, june 2018

Copyright (c) 2018 Kees Schollaart

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