Azure 函数 - 从事件中心触发器向 Azure SignalR 服务发送消息答案

【问题标题】：Azure Function - Send a message from an Event Hub Trigger to an Azure SignalR ServiceAzure 函数 - 从事件中心触发器向 Azure SignalR 服务发送消息
【发布时间】：2020-07-02 17:27:25
【问题描述】：

我正在尝试从 Azure Function EventHub 触发器向 Azure SignalR 服务发送消息。

我没有得到异常，甚至没有输出窗口上的信息，我做错了什么？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Azure.EventHubs;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.SignalRService;
using Microsoft.Extensions.Logging;

namespace AzureFunction_EventHubToSignalR
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static async Task Run([EventHubTrigger("dio", Connection = "EventHubSharedAccessPolicyConnectionString")] EventData[] events, 
                                     [SignalR(HubName = "%AzureSignalRHubName%")] IAsyncCollector<SignalRMessage> signalRMessages, 
                                     ILogger log)
        {
            var exceptions = new List<Exception>();

            foreach (EventData eventData in events)
            {
                try
                {
                    string messageBody = Encoding.UTF8.GetString(eventData.Body.Array, eventData.Body.Offset, eventData.Body.Count);

                    await signalRMessages.AddAsync(
                       new SignalRMessage
                       {
                           Target = "BroadcastMessage",
                           Arguments = new[] { messageBody }
                       });

                    await signalRMessages.FlushAsync();

                    // Replace these two lines with your processing logic.
                    log.LogInformation($"C# Event Hub trigger function processed a message: {messageBody}");
                    await Task.Yield();
                }
                catch (Exception e)
                {
                    log.LogError($"Event Hub trigger failed to process or send a message: {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();
        }
    }
}

【问题讨论】：

标签： c# azure .net-core azure-eventhub azure-signalr

【解决方案1】：

由于某种原因，我无法使用 SignalR 扩展使其工作，而是最终使用了原始 SignalR 包（Microsoft.AspNetCore.SignalR.Client、Microsoft.AspNetCore.SignalR.Client.Core) 向 Azure SignalR 服务发送消息..

 [FunctionName("Function1")]
 public static async Task Run([EventHubTrigger("dio", Connection = "EventHubSharedAccessPolicyConnectionString")] EventData[] events,
                              [SignalRConnectionInfo(HubName = "%AzureSignalRHubName%")] SignalRConnectionInfo connectionInfo,
                              ILogger log)
 {
 ....
     //Build connection with token
     HubConnection _connection = new HubConnectionBuilder()
     .WithUrl(connectionInfo.Url, option =>
     {
          option.Headers.Add("Authorization", $"Bearer {connectionInfo.AccessToken}");
     })
     .Build();

     //Start the hub connection
     await _connection.StartAsync();

     //My Hub has a BroadcastMessage method that receives 2 arguments
     await _connection.SendAsync("BroadcastMessage", "test", "test", default);
 ...
 }

【讨论】：