Simplest Asynchronous Web Service Call sample – C#

1. Create an Empty Web Site (preferable Http and not File System).

2. Right the project -> choose Add -> Add New Item..

3. Choose Web Services

Then you will see the screen below.


4. From pull down menu Build -> Build Solution.

5. Right click the WebService.asmx then choose View in browser



5. Open another instance of Visual Studio 2010.

6. Create an Empty Web Site.

7. Add a Web Form, right click on project -> Add -> Add New Item… then choose Web Form

8. Pull a Button from Toolbox to the web form.

9. Add Web Reference, right click on project -> Add Web Reference

10. Type if the URL you got from step 5 above.

11. Put the code in code behind file as follow.

protected void Button1_Click(object sender, EventArgs e)


ws.BeginHelloWorld(HelloCompleted, null);


protected void HelloCompleted(IAsyncResult result)


string str= ws.EndHelloWorld(result);




12. Run.

Download the complete code from The sample file name is webtemp.rar. My MSN ID is

About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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1 Response to Simplest Asynchronous Web Service Call sample – C#

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