Updating a website with data from an asynchronously called Webservice

Hi!

I wrote the following code to update a label on my aspx-page with data retrieved by an asynchronously called Webservice.

Protected Sub Page_Load(ByVal senderAs Object,ByVal eAs System.EventArgs)Handles Me.LoadIf Not Page.IsPostBackThen Dim wsAs localhost.WebServiceTest =New localhost.WebServiceTestDim ResultAs IAsyncResult = ws.Beginmessages(AddressOf renderResult, ws)End If End Sub Private Sub renderResult(ByVal ResultAs IAsyncResult)Dim wsAs localhost.WebServiceTest =CType(Result.AsyncState, localhost.WebServiceTest) Label1.Text = ws.Endmessages(Result)End Sub

The problem is that the Label (which is surrounded by an Updatepanel) does not get updated with the value returned by the Webservice although "renderResult" is executed correctly. (Maybe the problem is that the asynchronous function is called in a different thread on the webserver?)

Do you have any ideas or solutions to solve this issue?

Thank you

No suggestions?

Try doing your asynchronous webservice calls from the client-side rather than from the server.

http://www.asp.net/learn/ajax-videos/video-79.aspx

http://www.asp.net/AJAX/Documentation/Live/tutorials/ASPNETAJAXWebServicesTutorials.aspx

As DisturbedBuddha points out, you would probably want to do this sort of thing client side (remember the runat=server thing).

But, if youreally want to do this server side, my first question would be - is the updatepanel inside a form?

Cheers

Martin

Thank you for your help.

Calling the webservice client-side worked!

Updating gridview without postback

Hi!

I want to refresh a gridview without doing postback every second and for do it I use a System.Timer.

I have the grid into an updatepanel and I want to know how can I make, from the elapsed event of the timer, to refresh the grid.

I am trying to use theICallbackEventHandlerbut I can't reach my target.

Could anyone said me if I can do it and how could I do?

I have search code samples but they aren't useful for me.

Try this:

Put a button on the form somewhere, set the onclick event to trigger an update of the gridview. Check that pressing this button updates the gridview as expected.

Make this button invisible by using style='Display:none;'.

On the timer elapsed event add a call to myButton.Click();

Andy.

Finally I have used the Anthem.net library and its panel component. It was very easy working with it doing the refresh without the postback.

There is more information inhttp://www.codeproject.com/Ajax/AnthemNET.asp.

Use "Hello World Using Client Script" in UserControl

Hi

I want to create a asp.net user control for dynamic date entering, and I'm trying to use the same approach as in the example:

 <form runat="server">
 <div>
 Search for
 <input id="SearchKey" type="text" />
 <input id="SearchButton" type="button"
 value="Search"
 onclick="DoSearch()" />
 </div>
 </form>
 <hr style="width: 300px" />
 <div>
 <span id="Results"></span>
 </div>
 <script type="text/javascript"
 function DoSearch()
 {
 var SrchElem = document.getElementById("SearchKey");
 Samples.AspNet.HelloWorldService.HelloWorld(SrchElem.value,
 OnRequestComplete);
 }
 function OnRequestComplete(result)
 {
 var RsltElem = document.getElementById("Results");
 RsltElem.innerHTML = result;
 }
 </script>

The problem is if I use <input id=SearchKey> -tag for the result, then there will be problems if I use the same control multiple times on one page (the id is not unique, and the OnRequestComplete will update every <input>-tag with id=SearchKey). If I change it to <input id=SearchKey runat=server>, asp will render unique id's for the <input>, but then .getElementById() does not find "object".

I have done a "workaround" where I passes the object's Id to the Webservice, and returns it in an array together with the result, but I don't think this is "a great way". Is there any other solution? A better one?

function DoSearch(CallerId)
{
var SrchElem = document.getElementById(CallerId);
Samples.AspNet.HelloWorldService.HelloWorld(this.id, SrchElem.value,
OnRequestComplete);
}

function OnRequestComplete(result)
{

var objectId = result[0].toString();
var WebServiceResult = result[1].toString();
var RsltElem = document.getElementById(objectId);
RsltElem.innerHTML = result;
}

Regards

Lars K.

This is a common problem... if you use ASP.NET server IDs you need to reference the client ID in client script:

var Ctl = $('<%= SearchKey.ClientID %>');

will do the trick in finding the control reliably.

You also need to use this if use MasterPages or any contained control, so as a general rule this is the best way to reference server based page variables.

+++ Rick --