Programming ASP.NET 3.5, 4th Edition

Creating and Consuming AJAX-Enabled Web Services

AJAX (Asynchronized JavaScript and XML) is a popular way to enhance web pages to make them more interactive for the user. In an AJAX style, instead of submitting an entire page to the server and generating a new page, you make connections to servers with JavaScript and then use the results to change the existing page. Originally, this was done with XML, but the data can be in any format and still be considered AJAX. In VS2008, there is direct support for AJAX in ASP.NET, and combined with WCF you can call web services directly from the browser in JavaScript.

When you’re building a service for use in ASP.NET AJAX, VS2008 can perform most of these steps for you. Let’s build an AJAX page using this built-in support.

In the preceding example, you created a page to search for text using Microsoft’s MS Live Search service. In this demonstration, you’ll repeat the exercise but you’ll use AJAX to view the results without page refreshes. In contrast to the preceding example, rather than calling the Live Search service directly from the page, you must first create an AJAX-enabled WCF service of your own that will call Live Search on behalf of your page’s. The page itself must also be AJAX-enabled.

To create the new service, right-click the C16_WebServiceClients project in the Solution Explorer and click Add New Item. From the Add New Item dialog, select “AJAX-enabled WCF Service” and call it LiveSearchWithAjax.svc, as shown in Figure 16-17. Click ...