The term "web method" has several meanings, among them:
- In the legacy ASMX web service technology, web service operations were created by adding the [WebService] attribute to a public class, and the [WebMethod] attribute to public instance methods of such a class. these methods would then be exposed as web service operations.
- There is a related technology, "Page Methods" that is part of ASP.NET. ...
The WebMethod attribute is added to each method we want to expose as a Web Service. ASP.NET makes it possible to map traditional methods to Web Service operations through the System. Web. Services. WebMethod attribute and it supports a number of properties that control the behavior of the methods.Jan 29, 2012
Full
AnswerCan you call a method directly in a user control using JQuery?
You cannot call a method directly in a user control using Jquery Ajax.
Is webmethod static or dynamic?
WebMethod should be static. So, You can put it in the user control and add a method in the page to call it.
Can you access WebMethod from user control?
You can't access WebMethod from user control but you can perform your functionality.
Calling Web Services with ASP.NET AJAX
Web Services Configuration
- When a new Web Site project is created with Visual Studio 2008, the web.config file has a numb…
Listing 1. ASP.NET AJAX Web Service Handler ConfigurationThis HttpHandler replacement is made in order to allow JavaScript Object Notation (JSON) calls to be made from ASP.NET AJAX pages to .NET Web Services using a JavaScript Web Service proxy. ASP.NET AJAX sends JSON … - Listing 2. Web Service Request Message Serialized to JSON> [!NOTE] the operation name is defi…
Listing 3. Web Service Response Message Serialized to JSONIn the next section you'll see how to create Web Services capable of handling JSON request messages and responding with both simple and complex types.
Creating AJAX-Enabled Web Services
- The ASP.NET AJAX framework provides several different ways to call Web Services. You can us…
Whether or not you're new to ASP.NET Web Services, you'll find it straightforward to create and AJAX-enable services. The .NET framework has supported the creation of ASP.NET Web Services since its initial release in 2002 and the ASP.NET AJAX Extensions provide additional AJAX funct… - Listing 4 shows an example of applying the WebMethod attribute to a method named GetCusto…
Listing 4. Using the WebMethod Attribute in a Web ServiceThe GetCustomersByCountry() method accepts a country parameter and returns a Customer object array. The country value passed into the method is forwarded to a business layer class which in turn calls a data layer class to retriev…
Using the ScriptService Attribute
- While adding the WebMethod attribute allows the GetCustomersByCountry() method to be calle…
Listing 5 shows an example of applying the ScriptService attribute to a Web Service class named CustomersService.
Using the ScriptMethod Attribute
- The ScriptService attribute is the only ASP.NET AJAX attribute that has to be defined in a .NET …
The UseHttpGet property can be used when a Web Method should accept GET requests as opposed to POST requests. Requests are sent using a URL with Web Method input parameters converted to QueryString parameters. The UseHttpGet property defaults to false and should onl… - Listing 6. Using the ScriptMethod attribute with the UseHttpGet property.An example of the head…
GET /CustomerViewer/DemoService.asmx/HttpGetEcho?input=%22Input Value%22 HTTP/1.1
Working with Complex Types
- Listing 5 showed an example of returning a complex type named Customer from a Web Service. …
In cases where a nested complex type used by a Web Service must also be used in a client page, the ASP.NET AJAX GenerateScriptType attribute can be added to the Web Service. For example, the CustomerDetails class shown in Listing 9 contains Address and Gender properties which rep… - Listing 9. The CustomerDetails class shown here contains two nested complex types.The Addre…
Listing 10. Using the GenerateScriptService attribute to define nested types that should be available to the client.By applying the GenerateScriptType attribute to the Web Service, the Address and Gender types will automatically be made available for use by client-side ASP.NET A…
Creating JavaScript Proxies
- Calling a standard Web Service (.NET or another platform) typically involves creating a proxy obj…
Creating a JavaScript proxy that can call Web Services is accomplished by using the ScriptManager's Services property. This property allows you to define one or more services that an ASP.NET AJAX page can call asynchronously to send or receive data without requiring postb… - Adding a reference to the CustomersService.asmx through the ScriptManager control causes a …
If debugging is enabled in web.config a debug version of the JavaScript proxy will be embedded in the page as shown next:The JavaScript proxy created by the ScriptManager can also be embedded directly into the page rather than referenced using the <script> tag's src attribute. Thi…
Using JavaScript Proxies
- Once a Web Service is referenced by an ASP.NET AJAX page using the ScriptManager control, a …
An example of using a JavaScript proxy to call a Web Method named GetCustomersByCountry() is shown in Listing 13. The GetCustomersByCountry() function is called when an end user clicks a button on the page. - Listing 13. Calling a Web Service with a JavaScript proxy.This call references the InterfaceTraini…
Figure 1: Binding data obtained by making an asynchronous AJAX call to a Web Service. (Click to view full-size image)
Handling Errors
- Asynchronous callbacks to Web Services can encounter different types of errors such as the net…
Listing 14. Defining an error callback function and displaying errors.Any errors that occur when the Web Service is called will trigger the OnWSRequestFailed() callback function to be called which accepts an object representing the error as a parameter. The error object exposes severa…
Handling XML Data Returned from a Web Service
- Earlier you saw how a Web Method could return raw XML data by using the ScriptMethod attribu…
Retrieving XML data from a Web Service is no different than retrieving other data types. Start by invoking the JavaScript proxy to call the appropriate function and define a callback function. Once the call returns you can then process the data in the callback function. - Listing 15 shows an example of calling a Web Method named GetRssFeed() that returns an Xml…
Listing 15. Working with XML data returned from a Web Service.This example passes a URL to an RSS feed and processes the returned XML data in the OnWSRequestComplete() function. OnWSRequestComplete() first checks to see if the browser is Internet Explorer to know whether …
Handling Complex Types
- Complex types accepted or returned by a Web Service are automatically exposed through a Java…
To answer this question, assume that an ASP.NET AJAX page displays customer data and allows end users to update a customer's address. If the Web Service specifies that the Address type (a complex type defined within a CustomerDetails class) can be sent to the client then the update … - Figure 3: Output creating from calling a Web Service that returns RSS data. (Click to view full-siz…
Listing 16 shows an example of client-side code that invokes an Address object defined in a Model namespace, fills it with updated data and assigns it to a CustomerDetails object's Address property. The CustomerDetails object is then passed to the Web Service for processing.
Creating and Using Page Methods
- Web Services provide an excellent way to expose re-useable services to a variety of clients inclu…
ASP.NET AJAX provides another mechanism for making Web Service-like calls without creating standalone .asmx files. This is done by using a technique referred to as "page methods". Page methods are static (shared in VB.NET) methods embedded directly in a page or code-beside file … - Listing 17. Defining page methods.When ScriptManager detects the presence of Web Methods i…
Listing 18. Calling page methods with the PageMethods JavaScript object.Using the PageMethods object is very similar to using a JavaScript proxy object. You first specify all of the parameter data that should be passed to the page method and then define the callback functio…
The AutoCompleteExtender and the ASP.NET AJAX Toolkit
- The ASP.NET AJAX Toolkit (available from http://ajax.asp.net) offers several controls that can b…
The AutoCompleteExtender control can be used to extend existing functionality of a textbox and help users more easily locate data they're looking for. As they type into a textbox the control can be used to query a Web Service and shows results below the textbox dynamically. Figure 4 show… - Using the AutoCompleteExtender within an ASP.NET AJAX page requires that the AjaxControlTo…
Figure 4: Using the AutoCompleteExtender control. (Click to view full-size image)
Conclusion
- ASP.NET AJAX provides excellent support for calling Web Services without writing a lot of custom JavaScript code to handle the request and response messages. In this article you've seen how to AJAX-enable .NET Web Services to enable them to process JSON messages and how to define JavaScript proxies using the ScriptManager control. You've also seen how JavaScript proxies ca…
Bio
- Dan Wahlin (Microsoft Most Valuable Professional for ASP.NET and XML Web Services) is a .NE…
Scott Cate has been working with Microsoft Web technologies since 1997 and is the President of myKB.com (www.myKB.com) where he specializes in writing ASP.NET based applications focused on Knowledge Base Software solutions. Scott can be contacted via email at scott.cate…