AJAX Client Side Programming
page 5 of 8
by Brian Mains
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Views (Total / Last 10 Days): 39300/ 79

Web Services

ASP.NET AJAX heavily uses web services to perform client-server communication.  There are multiple ways to create a web service that the client can connect with.  The one way I'll touch upon here is the System.Net.WebServiceProxy class.  This class is the proxy to make a call to a method on a web service.  Whether the web service succeeds or fails, the appropriate method call is made.

As a simple test, I defined a WebMethod inside of my page as such:

Listing 15

public static string GetOutput()
  return "Successful";

The following markup simply makes the call to the page method and supplies the label with the text value returned from the web service method, if no errors occurred.  Otherwise, if errors did occur, the text "Error" appears from the onFailure callback.

Listing 16

<script language="javascript" type="text/javascript">
      function pageLoad()
            var wsProxy = new Sys.Net.WebServiceProxy();
            var label = $get("output");
            var request = wsProxy._invoke("http://localhost:61379/testloader.aspx", 
                  "GetOutput", false, {}, onSuccess, onFailure, label);
      function onSuccess(result, userContext, methodName)
            userContext.innerText = result;
      function onFailure(result, userContext, methodName)
            userContext.innerText = "Error";
<span id="output"></span>

Running this page makes the call to the web service and returns the result to the label.  A nice feature of Visual Studio 2008 is that you can debug both the server-side and client-side call to ensure it works correctly.

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User Comments

Title: Good Article   
Name: Amol
Date: 2010-09-17 2:48:44 AM
Very good article
Title: Informative   
Name: PickaTutorial.com
Date: 2010-08-07 2:44:15 AM
A good informative resource.
Title: good   
Name: good
Date: 2010-07-23 2:53:53 AM
Title: Good   
Name: Ananth
Date: 2009-04-15 12:51:48 PM
Title: Parameters to be passed webserivices (reply)   
Name: Brian Mains
Date: 2009-02-09 8:59:45 AM

You could pass the values as straight parameters; I preferrably like to have the web service use a custom object that has those parameters. The reason is that it makes maintenance easier. If you need 21 parameters later, you have to change the web service, and anything that connects to this web service.

This way, you simply add a parameter to the class and make use of it in the web service, less coding work to do this way.

The proxy generator will also generate the class that's accepted by the parameter, as long as it's simple enough (not deeply nested properties), and you can instantiate this and pass it to the web service call.
Title: Parameters to be passed webserivices.   
Name: Rupesh Kumar Tiwari
Date: 2009-02-09 5:37:28 AM
I have to pass 20 parameters to a webmethod from the clientside.so, is it advisable to make a webmethod that will take 20 parameters or else i have to send one array of parameters to reduce the confusion. Any other suggesion do you have. then kindly tell me. Any quick response is appreciable.

Title: Thanks a lot for the info   
Name: The Black Knight
Date: 2008-11-19 6:24:52 PM
Excellent info
Title: Nice Article   
Name: ---
Date: 2008-06-21 5:40:01 AM
really nice article, it is good for the beginners.
good job :)
Title: dragpanel extender in ajax controls   
Name: lalitha
Date: 2008-06-12 5:46:21 PM
its not working as i had written as it was mentioned here in the tutorial plse give a brief coding about that control
Title: expect more   
Name: sivaram
Date: 2008-05-02 4:50:01 AM
ok .i expected more.If possible plz explain with the examples
Title: nice but shud little brief   
Name: snehal
Date: 2008-04-30 3:20:58 PM
nice article but give more details on ajax its merits... funnalities future implementation ....etc thnx
Title: thanks   
Name: suhas kudekar
Date: 2008-04-23 9:02:58 AM
its very new concept 4 me. thanks
Title: very good   
Name: panakj lahjoti
Date: 2008-04-21 7:34:42 AM
i found this aticle very useful for the newbies
Title: Very helpful   
Name: Raviraj
Date: 2008-04-20 1:28:30 PM
thanks it is very helpful to me

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