供 MQTT 设备订阅的 Azure C2D 消息

Question

我已成功将两个实际设备连接到 Azure IoTHub(在同一个 IoT 中心)，并希望第二个设备接收第一个设备发送的消息。因此，在普通的 MQTT 代理中，第二个设备仅订阅该主题，但 Azure没有普通的 MQTT 代理。

我现在想做的是编写一个 Azure 函数，每当通过事件中心触发器在 IoTHub 中接收到来自第一台设备的消息时，该函数就会触发；并将带有接收到的消息(字符串)的C2D消息发送到第二设备。要实现第二个设备订阅此主题:devices/secondDevice/messages/devicebound

这是我的函数

#r "Microsoft.Azure.EventHubs"


using System;
using System.Text;

using Microsoft.Azure.EventHubs;
using Microsoft.Azure.Devices;

static ServiceClient serviceClient;
static string connectionString = ".........pXH9WI.....";  
static string targetDevice = "secondDevice";

public static async Task Run(EventData[] events, ILogger log)
{
    var exceptions = new List<Exception>();
    serviceClient = ServiceClient.CreateFromConnectionString(connectionString);
    foreach (EventData eventData in events)
    {
        try
        {
            string messageBody = Encoding.UTF8.GetString(eventData.Body.Array, eventData.Body.Offset, eventData.Body.Count);

            // Replace these two lines with your processing logic.
            log.LogInformation($"C# Event Hub trigger function processed a message: {messageBody}");
            await Task.Yield();
            var commandMessage = new Message(Encoding.ASCII.GetBytes(messageBody));
            await serviceClient.SendAsync(targetDevice, commandMessage);  //  send the message to the second device that the first device sent to IoTHub
        }
        catch (Exception e)
        {
            // We need to keep processing the rest of the batch - capture this exception and continue.
            // Also, consider capturing details of the message that failed processing so it can be processed again later.
            exceptions.Add(e);
        }
    }

    // Once processing of the batch is complete, if any messages in the batch failed processing throw an exception so that there is a record of the failure.
    if (exceptions.Count > 1)
        throw new AggregateException(exceptions);

    if (exceptions.Count == 1)
        throw exceptions.Single();
}

这是 .json 代码:

{
  "bindings": [
    {
      "type": "eventHubTrigger",
      "name": "events",
      "direction": "inout",
      "eventHubName": "samples-workitems",
      "cardinality": "many",
      "connection": "myIoTHub_events_IOTHUB",
      "consumerGroup": "$Default"
    }
  ]
}

我正在接收第一台设备的消息，但在第二台设备订阅的主题中没有看到该消息。

有什么想法吗？我通过门户网站完成所有这些工作是因为我目前在 VSCode 方面遇到了很多问题，并且希望快速解决这个 C2D 问题。

谢谢

Answer 1

第二个设备应按照 docs 订阅主题过滤器 # 。那么话题就变成了:

devices/secondDevice/messages/devicebound/#