Azure应用服务无法从Azure IoT中心获取数据

Question

I want to use Azure App Service to get data from Azure IoT Hub.

I try to register callback event to IoT Hub in the Application_Start() function.

When I can run my program with Visual Studio 2017 on my PC, event trigger normally by Azure IoT Hub and get the data.

Unfortunately, when I deploy to the Azure cloud which is the service "Azure App Service", it only can get the trigger event from Azure IoT Hub when the App Service start up in few seconds.

There is no data get back from Azure IoT Hub and the event doesn't trigger anymore.

I don't know the reason. Any advice will be appriciated.

Here is the event trigger code will run at the initial of the App Service. The entry point is Main() function.

    using Microsoft.ServiceBus.Messaging;
    using System;
    using System.Collections.Generic;
    using System.Configuration;
    using System.Linq;
    using System.Threading.Tasks;
    using System.Web;
    using TelemetryEPHostConsoleApp;

    namespace MCM100_Dashboard.App_Start.TelemetryProcessor
    {
        public class TelemetryMain
        {
            private const string STORAGEACCOUNT_PROTOCOL = "https";// We use HTTPS to access the storage account

            public async static void Main()
            {
                var mainTask = new Task(GetAzureData);
                mainTask.Start();
                await mainTask;
            }
            public static string GetAzureData()
            {
               // IoT Hub
                string iotHubConnectionString = ConfigurationManager.AppSettings["IoTHub.ConnectionString"];
                string eventHubPath = "messages/events";// It's hard-coded for IoT Hub
                string consumerGroupName = "mcmpush";// It's hard-coded for this workshop

                // Storage Account
                string storageAccountName = ConfigurationManager.AppSettings["StorageAccount.Name"];
                string storageAccountKey = ConfigurationManager.AppSettings["StorageAccount.Key"];
                string storageAccountConnectionString = CombineConnectionString(storageAccountName, storageAccountKey);
                string eventProcessorHostName = "eventprocessorhost";
                string leaseName = eventProcessorHostName;

                EventProcessorHost eventProcessorHost = new EventProcessorHost(
                    eventProcessorHostName,
                    eventHubPath,
                    consumerGroupName,
                    iotHubConnectionString,
                    storageAccountConnectionString,
                    leaseName);


                var options = new EventProcessorOptions
                {
                    InitialOffsetProvider = (partitionId) => DateTime.UtcNow
                };
                options.ExceptionReceived += (sender, e) => { Console.WriteLine(e.Exception); };
                re: try
                {
                    eventProcessorHost.RegisterEventProcessorAsync(options).Wait();
                }
                catch (Exception e)
                {
                    System.Threading.Thread.Sleep(1000);
                    goto re;
                }


                eventProcessorHost.UnregisterEventProcessorAsync().Wait();

                return "";

            }

            private static string CombineConnectionString(string storageAccountName, string storageAccountKey)
            {
                return "DefaultEndpointsProtocol=" + STORAGEACCOUNT_PROTOCOL + ";" +
                    "AccountName=" + storageAccountName + ";" +
                    "AccountKey=" + storageAccountKey;
            }
        }
    }

    using Microsoft.ServiceBus.Messaging;
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Net;
    using System.Configuration;
    using System.IO;
    using System.Web;

    namespace TelemetryEPHostConsoleApp
    {
        class TelemetryEventProcessor :IEventProcessor
        {
            static WebServerConnector _webSC = new WebServerConnector();

            async Task IEventProcessor.CloseAsync(PartitionContext context, CloseReason reason)
            {
                if (reason == CloseReason.Shutdown)
                {
                    await context.CheckpointAsync();
                }
            }

            Task IEventProcessor.OpenAsync(PartitionContext context)
            {
                return Task.FromResult(null);
            }

            async Task IEventProcessor.ProcessEventsAsync(PartitionContext context, IEnumerable messages)
            {
                // hope to trigger event
                foreach (EventData eventData in messages)
                {
                    string data = Encoding.UTF8.GetString(eventData.GetBytes());

                }

                //Call checkpoint every 5 minutes, so that worker can resume processing from 5 minutes back if it restarts.
                if (this.checkpointStopWatch.Elapsed > TimeSpan.FromMinutes(5))
                {
                    await context.CheckpointAsync();
                    this.checkpointStopWatch.Restart();
                }
            }

            private void ProcessMessage(string data)
            {
               return "";
            }

        }
    }

Answer 1

Immediately after RegisterEventProcessorAsync you are executing UnregisterEventProcessorAsync . Why is that? You don't allow much time for events getting processed. You might be better off using a continuous running webjob for reading data from the IoT hub.

You should call UnregisterEventProcessorAsync only when you want to stop listening for incoming events. The runtime will call Task IEventProcessor.ProcessEventsAsync(PartitionContext context, IEnumerable messages) any number of times after you have registered the eventprocessor and before unregistering.

Also, what is up with the return ""; I see a couple of times?