调用Event Hub CreateBatchAsync时连接失败问题求助

按照微软文档创建Azure免费试用版Event Hub后，在.Net示例应用中配置了connectionString和eventHubName，运行代码时调用CreateBatchAsync方法抛出错误：A connection attempt failed because the connected party did not properly respond。尝试了连接字符串和访问控制两种认证方式，均出现相同错误。

示例代码如下：

class Program
{
    const string eventHubName = "<eventHubName>";
    const string connectionString = @"<connectionString>";

    public static async Task Main(string[] args)
    {
         await EventHubIngestionAsync();
    }

    public static async Task EventHubIngestionAsync()
    {
        await using (var producerClient = new EventHubProducerClient(connectionString, eventHubName))
        {
            int counter = 0;
            for (int i = 0; i < 100; i++)
            {
                int recordsPerMessage = 3;
                try
                {
                    var records = Enumerable
                        .Range(0, recordsPerMessage)
                        .Select(recordNumber => $"{{\"timeStamp\": \"{DateTime.UtcNow.AddSeconds(100 * counter)}\", \"name\": \"{($"name {counter}")}\", \"metric\": {counter + recordNumber}, \"source\": \"EventHubMessage\"}}");
                    
                    string recordString = string.Join(Environment.NewLine, records);

                    EventData eventData = new EventData(Encoding.UTF8.GetBytes(recordString));
                    Console.WriteLine($"sending message {counter}");
                    // Optional "dynamic routing" properties for the database, table, and mapping you created. 
                    //eventData.Properties.Add("Table", "TestTable");
                    //eventData.Properties.Add("IngestionMappingReference", "TestMapping");
                    //eventData.Properties.Add("Format", "json");

                   using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();
                    eventBatch.TryAdd(eventData);
                    IEnumerable<EventData> dd = null;
                    await producerClient.SendAsync(dd);
                }
                catch (Exception exception)
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("{0} > Exception: {1}", DateTime.Now, exception.Message);
                    Console.ResetColor();
                }

                counter += recordsPerMessage;
            }
        }
    }
}

针对这个连接错误和代码问题，可按以下步骤排查修复：

• 网络/防火墙拦截
  该错误通常是本地防火墙、公司网络或代理阻止了Event Hub的AMQP端口（5671/5672）。可以尝试切换到AMQP over WebSockets（使用443端口，通常不会被拦截），修改客户端初始化代码：

  var producerOptions = new EventHubProducerClientOptions
  {
      TransportType = EventHubsTransportType.AmqpWebSockets
  };
  await using var producerClient = new EventHubProducerClient(connectionString, eventHubName, producerOptions);
  

• 连接字符串验证
  确认连接字符串是Event Hub命名空间的有效连接字符串（而非Event Hub实体的），检查Endpoint、SharedAccessKeyName、SharedAccessKey是否复制正确，没有多余空格或字符。免费层命名空间需确认处于正常状态，未超出配额。

• 修复代码逻辑错误
  代码中存在明显错误：SendAsync传入了null的IEnumerable<EventData>，这会引发异常。同时需要检查TryAdd的返回值，确保事件成功加入批次：

  using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();
  if (!eventBatch.TryAdd(eventData))
  {
      // 若当前批次无法容纳事件，发送现有批次后创建新批次
      await producerClient.SendAsync(eventBatch);
      eventBatch = await producerClient.CreateBatchAsync();
      if (!eventBatch.TryAdd(eventData))
      {
          throw new InvalidOperationException("单个事件大小超过批次最大限制");
      }
  }
  // 发送批次
  await producerClient.SendAsync(eventBatch);
  

• 免费层配额限制
  Azure Event Hub免费层有吞吐量限制（每秒1MB、1000个事件），若循环发送速度过快可能触发限制。可在循环中添加await Task.Delay(100);降低发送频率，避免触发限流。

内容的提问来源于stack exchange，提问作者RK Tamil