MVC 2 Async Controller COMET concept RSS

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  jimslattery

  Member

  4 Points

  4 Posts

  MVC 2 Async Controller COMET concept

  May 01, 2010 05:14 PM|LINK

  Ok, so I am new to Async controllers, and the COMET concept. But I have successfully created a COMET implementation using MVC 2 RTM and jQuery.

  I am working on a Web application for organizing a physical filing system (for a large group of file cabinets in an office). I need a synchronization subsystem which will keep edited content synchronized among the many clients.

  The following code WORKS. When I edit a "file" record using the service, the content from the response of the Async controller action is then sent to a custom alert subsystem. I am now wiring up the content sync subsystem so that when a file is edited, the contents are pushed out to the other clients.

  Question: Am I doing this right? Am I using the .net framework and threading appropriately? Any suggestions?

  Here is the Async Controller:

  public class SyncController : AsyncController
      {
          private FileSync sync;
          protected override void Initialize(System.Web.Routing.RequestContext requestContext)
          {
              sync = new FileSync();
              base.Initialize(requestContext);
          }
         
          public void IndexAsync()
          {
              sync.Listen();
          }
          public ActionResult IndexCompleted()
          {
              System.Text.StringBuilder sb = new System.Text.StringBuilder();
              foreach (File item in FileSync.UpdateList)
              {
                  sb.AppendFormat("Updated File: {0}", item.fileTitle);
              }

              //Simple return to alert the user of the titles of the files recently changed.
              return Content(sb.ToString());
          }
      }

  Here are the events and other classes:

  public delegate void FileUpdatedHandler();
  
  
      public class ListWithEvent : ArrayList
      {
          public event FileUpdatedHandler Updated;
  
  
          protected virtual void OnUpdated()
          {
              if (Updated != null)
              {
                  Updated();
              }
          }
  
  
          public override int Add(object value)
          {
              int ret = base.Add(value);
              OnUpdated();
              return ret;
          }
          
  
      }
      
  
      public class FileSync
      {
          public static ListWithEvent UpdateList;
          private EventWaitHandle wait;
          public FileSync()
          {
              if (UpdateList == null)
                  UpdateList = new ListWithEvent();
          }
          
  
          
  
          public void AddUpdate(File file)
          {
              UpdateList.Add(file);
          }
          public void ClearUpdates()
          {
              UpdateList.Clear();
          }
          
  
          public void Listen()
          {
              wait = new EventWaitHandle(false, EventResetMode.AutoReset);
              FileUpdatedHandler handler = new FileUpdatedHandler(UpdateList_Updated);
              UpdateList.Updated += handler;
              wait.WaitOne();
              wait.Close();
              UpdateList.Updated -= handler;
          }
  
  
          private void UpdateList_Updated()
          {
              wait.Set();
          }
          
  
      }

   

  here is the usage for an updated file:

  public void UpdateFile(File file, string UserName)
  {
              

    }
  
  here is the jQuery ajax function in use:
  function SyncInit() {
          $.ajax({
              url: '/FileMaster/Sync/Index',
              type: 'post',
              beforeSend: function (oXhr) { oXhr.setRequestHeader('Connection', 'Keep-Alive'); },
              dateType: 'html',
              success: function (data) { window.parent.$$.Alert.SetAndOpen(data); SyncInit(); },
              cache: false,
              async: true
  
          });
      }