带有回调的.NET异步webservice调用

2 回答

• 1

  将任务保留在IIS上运行是危险的，应用程序域可能会在方法完成之前关闭，这很可能发生在您身上 . 如果您使用HostingEnvironment.QueueBackgroundWorkItem，您可以告诉IIS，正在进行的工作需要保持运行 . 这将使app域保持活动90秒（默认情况下）

  using System;
  using System.Data.SqlClient;
  using System.Threading.Tasks;
  using System.Web.Services;
  
  namespace Sample
  {
      [WebService(Namespace = "urn:Services")]
      [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
      public class MyWebService
      {
          [WebMethod]
          public string Request(string request)
          {
              // Step 1: Call the library method to generate data
              var lib = new MyLibrary();
              HostingEnvironment.QueueBackgroundWorkItem((token) =>
                  lib.GenerateDataAsync(() =>
                  {
                      // Step 2: Kick off a process that consumes the data created in Step 1
                  }));
  
              return "some kind of response";
          }
      }
  
      public class MyLibrary
      {
          public async Task GenerateDataAsync(Action onDoneCallback)
          {
              try
              {
                  using (var cmd = new SqlCommand("MyStoredProc", new SqlConnection("my DB connection string")))
                  {
                      cmd.CommandType = System.Data.CommandType.StoredProcedure;
                      cmd.CommandTimeout = 0;
                      cmd.Connection.Open();
  
                      // Asynchronously call the stored procedure.
                      await cmd.ExecuteNonQueryAsync().ConfigureAwait(false);
  
                      // Invoke the callback if it's provided.
                      if (onDoneCallback != null)
                          onDoneCallback();
                  }
              }
              catch (Exception ex)
              {
                  // Handle errors...
              }
          }
      }
  }
  

  如果你想要比90秒额外更可靠的东西，请参阅Stephen Cleary的文章“Fire and Forget on ASP.NET”以获得其他选项 .

  回复于 2024-04-18T16:43:01+08:00
• 2

  我找到了一个解决我的问题的方法，它涉及异步执行代码的旧式（Begin / End）方法：

  public void GenerateData(Action onDoneCallback)
      {
          try
          {
              var cmd = new SqlCommand("MyStoredProc", new SqlConnection("my DB connection string"));
              cmd.CommandType = System.Data.CommandType.StoredProcedure;
              cmd.CommandTimeout = 0;
              cmd.Connection.Open();
  
              cmd.BeginExecuteNonQuery(
                  (IAsyncResult result) =>
                  {
                      cmd.EndExecuteNonQuery(result);
                      cmd.Dispose();
  
                      // Invoke the callback if it's provided, ignoring any errors it may throw.
                      var callback = result.AsyncState as Action;
                      if (callback != null)
                          callback.Invoke();
                  },
                  onUpdateCompleted);
          }
          catch (Exception ex)
          {
              // Handle errors...
          }
      }
  

  onUpdateCompleted 回调操作作为第二个参数传递给 BeginExecuteNonQuery 方法，然后在 AsyncCallback （第一个参数）中使用 . 这在VS内部调试和部署到IIS时都像魅力 .

  回复于 2024-04-18T16:43:01+08:00