Unable to compile cloud to device Function in Azure Iot Hub

Question

I'm implementing a Azure Function to send a message to device on Iot Hub event trigger. The problem I'm getting a lot of compile errors with undefined namespaces.

The example is based on this article: https://sandervandevelde.wordpress.com/2016/06/14/closing-the-windows-iot-core-feedback-loop-using-azure-functions/

using System;
using Microsoft.Azure.Devices;
using System.Text;
using Newtonsoft.Json;

public static void Run(string myIoTHubMessage, ILogger log)
{
    var connectionString = "HostName=iot-hub-teste.azure-devices.net;SharedAccessKeyName=service;SharedAccessKey=hiden";

    var serviceClient = ServiceClient.CreateFromConnectionString(connectionString);

    var message = JsonConvert.DeserializeObject<Command>(myEventHubMessage);

    var commandMessage = new Message(Encoding.ASCII.GetBytes("Cloud to device message."));

    serviceClient.SendAsync("MyNodeDevice", commandMessage);
}

project.json

{
  "frameworks": {
  "net46":{
    "dependencies": {
      "Microsoft.Azure.Devices": "1.4.1"
      }
    }
  }
}

The errors:

2019-08-23T18:03:47.255 [Error] Function compilation error
Microsoft.CodeAnalysis.Scripting.CompilationErrorException : Script compilation failed.
   at async Microsoft.Azure.WebJobs.Script.Description.DotNetFunctionInvoker.CreateFunctionTarget(CancellationToken cancellationToken) at C:\azure-webjobs-sdk-script\src\WebJobs.Script\Description\DotNet\DotNetFunctionInvoker.cs : 314
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.Azure.WebJobs.Script.Description.FunctionLoader`1.GetFunctionTargetAsync[T](Int32 attemptCount) at C:\azure-webjobs-sdk-script\src\WebJobs.Script\Description\FunctionLoader.cs : 55
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.Azure.WebJobs.Script.Description.DotNetFunctionInvoker.GetFunctionTargetAsync(Boolean isInvocation) at C:\azure-webjobs-sdk-script\src\WebJobs.Script\Description\DotNet\DotNetFunctionInvoker.cs : 183
2019-08-23T18:03:47.427 [Error] run.csx(3,23): error CS0234: The type or namespace name 'Devices' does not exist in the namespace 'Microsoft.Azure' (are you missing an assembly reference?)
2019-08-23T18:03:47.477 [Error] run.csx(13,25): error CS0103: The name 'ServiceClient' does not exist in the current context
2019-08-23T18:03:47.541 [Error] run.csx(15,49): error CS0246: The type or namespace name 'Command' could not be found (are you missing a using directive or an assembly reference?)
2019-08-23T18:03:47.630 [Error] run.csx(15,58): error CS0103: The name 'myEventHubMessage' does not exist in the current context
2019-08-23T18:03:47.694 [Error] run.csx(17,30): error CS0246: The type or namespace name 'Message' could not be found (are you missing a using directive or an assembly reference?)
2019-08-23T18:03:47.766 [Error] Executed 'Functions.msg_to_device' (Failed, Id=de327298-1973-4bc5-82b6-0c7b05835dae)
Script compilation failed.

Zainu Zainu · Accepted Answer · 2019-08-23T21:12:00

1) Please add reference to Microsoft.Azure.Devices(1.18.1) and Microsoft.Azure.Devices.Client(1.21.0) in project.json and then include this in Function code

           using Microsoft.Azure.Devices;
           using Microsoft.Azure.Devices.Client;

2)The command class which is in the blogpost is missing:

            public class Command
            {
              public string devicename {get; set;}
              public int action {get; set;}
            }

3) There isn't any reference for myEventHubMessage. You are using myIoTHubMessage in place of that.

4)using Microsoft.Azure.Devices.Client should get you Message class.

This is how I did from plain C# class .Probably you can tweak this code as per your need in Azure Functions.

         CloudToDeviceMethod cloudtoDeviceMethod = new          
         CloudToDeviceMethod(DeviceMethod, 
         TimeSpan.FromSeconds(30), TimeSpan.FromSeconds(30)); 

         ServiceClient serviceClient = null;

         serviceClient = 
         ServiceClient.CreateFromConnectionString("HostName=myhub.azure- 
         devices.net;SharedAccessKeyName=service;SharedAccessKey=xxxxxxxxxxxxxxxx");

         await serviceClient.OpenAsync();  

         var response=await serviceClient.InvokeDeviceMethodAsync(DeviceId, 
         cloudtoDeviceMethod);   

         var json = @"{""Response:" + 
         response.GetPayloadAsJson()+@""",Status:""" + 
         response.Status + @"}";    

         if (serviceClient != null)
         {
            await serviceClient.CloseAsync();
         }

Unable to compile cloud to device Function in Azure Iot Hub

2 Answers