In my Article Preventing Duplicate Date With ASP.NET AJAX I’ve used ASP.NET AJAX With
Web Service Technology, Therefore I add this topic as an introduction how to access
Web services from client script in AJAX-enabled ASP.NET
Web pages. As well I write this topic to answer the common questions which most of the developers face while working with ASP.NET Ajax
Web Services especially in Microsoft ASP.NET official forum http://forums.asp.net/. ASP.NET enables you to create
Web services can be accessed from client script in
Web pages by using AJAX technology to make
Web service calls. Data is exchanged asynchronously between client and server, typically in JSON format. Lets go a head with the steps : 1-Create a new project , if you are using VS 2005 you have to create ASP.NET Ajax Enabled
Web site. 2-Add new Item , Choose
Web Service file . 3-To make
your Web Services accessible from script, first it must be an .asmx
Web service whose
Web service class is qualified with the ScriptServiceAttribute attribute and every method you are using to be called from Client script must be qualified with the WebMethodAttribute attribute. On other hand you can use
your Web page( CS or VB files) to add static methods accessible from Client Script , just you need to add WebMethod Attribute and set the EnablePageMethods attribute of the ScriptManager control to true.. The other condition is to register the ScriptHandlerFactory HTTP handler, which processes calls made from script to .asmx
Web services : <system.web>
<httpHandlers>
<remove verb="*" path="*.asmx"/> <add verb="*" path="*.asmx" type="System.
Web.Script.Services.ScriptHandlerFactory" validate="false"/>
</httpHandlers>
<system.web>
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
but this already added automatically for any
Web.config file of any ASP.NET AJAX Enabled WebSite or Project, So you don’t need to add it.
4-Avoid the default Method HelloWorld, then add
your method in
your asmx file lets say OurServerOutput , As a consequence
your Web service will be like this :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.
Web.Services;
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.
Web.Script.Services.ScriptService]
public class WebService : System.
Web.Services.WebService {
[WebMethod]
public string OurServerOutput() {
return "The Server Date and Time is : " + DateTime.Now.ToString();
}
}
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
5-Add ScriptManager Contol to
your aspx file then reference the
Web service by adding an asp:ServiceReference child element to the ScriptManager control and setting its path attribute to point to the
Web service, That generate a JavaScript proxy class for calling the specified
Web service from client script.
<asp:ScriptManager runat="server" ID="scriptManager">
<Services>
<asp:ServiceReference Path="WebService.asmx" />
</Services>
</asp:ScriptManager>
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
Basically ,to enable
your application to call
Web services(.asmx files) by using client script, the server asynchronous communication layer automatically generates JavaScript proxy classes. A proxy class is generated for each
Web service for which an <asp:ServiceReference> element is included under the <asp:ScriptManager> control in the page.
6-Create new button to call the JavaSciprt function and a label to display the returned value .
<input id="btnCallDateTime" type="button" value="Call
Web Service" onclick="CallDateTime()"/>
<asp:Label ID="lblOutupt" runat="server" Text="Label"></asp:Label>
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
7-Define the JavaScript code to call the
Web Service :
<script language="javascript" type="text/javascript">
function CallDateTime() {
WebService.OurServerOutput(OnSucceeded);
}
function OnSucceeded(result) {
var lblOutput = document.getElementById("lblOutupt");
lblOutput.innerHTML = result;
}
</script>
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
CallDateTime function calls the
Web Service Method OurServerOutput…
OnSucceeded function Used as the callback function that processes the
Web Service return value. which the result parameter is a simple parameter contain the Server Date Time value returned from the
Web Service .
Finally , when you complete these steps and run
your application you can press the button and retrieve Server Date time without postback.
Conclusion:
In this topic I describes how to access
Web services from client script in AJAX-enabled ASP.NET
Web pages With a full .NET Framework/JSON serialize, direct integration with the familiar .asmx
Web services ,Using simple example,Also you can connect with the database to return value by create WebMethod in
your Web Service file and the same steps you can use.
Next time I will show you more complex example which returns a complex type like objects.
Hope this help.
