wait page while excel is generated in ASP.net

I have a requirement, wherein i need to show a wait message while an excel report is being executed and when execution is complete, excel is written to response for user to save. Once save is done i need to hide the wait message.

I was able to show wait message but i am not able to hide the same when the execution is complete. I have used Ifames to achieve the same. i do all the processing required for excel in the iframe and write to the response in the same Iframe. i attempted to hide the wait message using Javascript but any JavaScript function written in onload,onunload, onbeforeunload etc of Iframe is not being executed.

Is there any way i can call a JavaScript function , Or is there any other approach to the problem.

From stackoverflow

• I did something like this a few years ago. I opened a new thread to do the background processing, then redirected to a "waiting" page. The wait page checks the status of the task and if completed, redirects back. That's a real easy solution. Check it out here

  Mike Robinson : +1 for a good read

• Here's how I'd do this:

  • Create an HttpHandler that generates the document, saves it (in cache/on disk/database, your call) and returns an identifier for the generated document
  • Call the HttpHandler using an AJAX call (use jQuery to make this really easy)
  • Use javascript/jQuery to display a waiting message/graphic/animation/whatever
  • In the AJAX request callback, redirect to a page that takes the generated identifier and sends the corresponding document as an attachment using the Content-Disposition header.

  As a side note, this would be a little more straightforward in ASP.NET MVC

  GenerateDocument HttpHandler stub:

  public class GenerateMyDocumentHandler : IHttpHandler
  {
      #region [ IHttpHandler Members ]
  
      public Boolean IsReusable
      {
          get { return true; }
      }
  
      public void ProcessRequest(HttpContext context)
      {
          var docIdentifier = this.GenerateDocument();
  
          context.Response.ContentType = "text/plain";
          context.Response.Write(docIdentifier.ToString("N"));
      }
  
      #endregion
  
      private Guid GenerateDocument()
      {
          var identifier = Guid.NewGuid();
  
          // Logic that generates your document and saves it using the identifier
  
          return identifier;
      }
  }
  

  Client Script stub:

  function generateDocument() {
      var result = $.get('/GenerateDocument.ashx', { any: 'parameters', you: 'need', go: 'here' }, generateDocumentCallback, 'text');
      // display your waiting graphic here
  }
  
  function generateDocumentCallback(result) {
      window.location.href = '/RetrieveDocument.ashx/' + result;
  }
  

  RetrieveDocument HttpHandler stub:

  public class RetrieveDocument : IHttpHandler
  {
      public void ProcessRequest(HttpContext context)
      {
          var identifier = new Guid(context.Request.Url.Segments[1]);
          var fileContent = this.GetFileAsBytes(identifier);
  
          context.Response.ContentType = "application/vnd.ms-excel";
          context.Response.AddHeader("Content-Disposition", "attachment; filename=yourfilename.xls");
          context.Response.OutputStream.Write(fileContent, 0, fileContent.Length);
      }
  
      private Byte[] GetFileAsBytes(Guid identifier)
      {
          Byte[] fileBytes;
          // retrieve the specified file from disk/memory/database/etc
  
          return fileBytes;
      }
  
      public Boolean IsReusable
      {
          get
          {
              return true;
          }
      }
  }
  

  rsapru : exactly what i wanted and worked like magic