Web Form with Progress Bar of Web Service Execution

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Introduction

The purpose of this article is to show how to get progress notifications of current web service progress. This will be achieved by using AJAX enabled web page, async call to web service and some easy CSS trick to display progress bar. This article also shows how to manage state of web service.

1. Look at the web service code. To manage state of a web service, we use a class named ProgressValues and Cache object. Values are stored in Cache with unique ID.

   public class ProgressValues
   {
       public bool AbortPressed = false;
       public int step = 0;
       public int value = 0;
   }       
   
   ProgressValues pw = new ProgressValues();
   Context.Cache[UID] = pw;

2. Web page has an AJAX Timer which is disabled by default and starts tick when user presses the start button and also has AJAX UpdatePanel to display progress bar, controls and GridView without full page postbacks.

3. When user clicks "Start Process" button we make async execution of a web service and pass values of IAsyncResult to Session object by the following lines of code:

   MyService.Test ts = new MyService.Test();
   
   // AsyncResult for async execution of service
   IAsyncResult my_ar;         
   
   // Start async execution of web service
   my_ar = ts.BeginGo(UID, steps, values, null, null); 
   
   // Remember AsyncResult in Session for later use
   Session["my_ar"] = my_ar;

4. When tick event occurs, we get IAsyncResult from Session and update controls with the following lines of code:

   // Get IAsyncResult from Session
   IAsyncResult my_ar = (IAsyncResult)Session["my_ar"]; 
   
   // Get ProgressValues from web service
   pw = ts.GetProcessValues(Session["WebServiceUID"].ToString()); 
   
   // Async execution of service done
   if (my_ar.IsCompleted)  

Using the Code

First of all, you need Microsoft AJAX installed on your web server. Second, you need to compile/deploy/start TestService project into your web server, then add Web References to "Test project" with name MyService. If you do this, then Proxy class for your service will exist and you can use this proxy class in Test project.

History

• 6^th August, 2008: Initial post