Beginning ASP.NET 4.5 in CSharp and VB Opsylum

376 x CHAPTER 10 ASP.NET AJAX
page. The downside of registering the web service in the master page is that its client JavaScript is referenced
in each and every page in your site. For a service you only use once or twice, it’s much better
to add a ScriptManagerProxy to the specific page(s) and register the service there. Within your page,
the ScriptManagerProxy control looks and acts like a normal ScriptManager control. However, in
reality it’s just a proxy control that relays all its settings to the true ScriptManager in the master page,
combining the settings for both controls. You used the ScriptManagerProxy control as follows to set
up the element:
All you need to do is refer to the service by setting the Path property. Just as with other server-side
URLs you have seen in this book so far, you can use the tilde (~) syntax to refer to the application’s
root.
Once you have registered the service, it becomes available in your client-side code. Note that
IntelliSense in VS is smart enough to discover the WCF services you have defined and registered. As
soon as you typed NameService followed by a dot in a client-side script block, IntelliSense kicked in
again and showed the public methods it found. This makes it extremely easy to find the correct services
you have defined in your site. This is a huge improvement over old versions of Visual Studio that
had only a fixed number of JavaScript-related items in the IntelliSense list. Starting with Visual Studio
2008, IntelliSense is now actually able to look at your code and fill the IntelliSense list with the right
variable names, methods, services, and so on that it finds in your code. In VS 2010 and VS 2012,
Microsoft improved IntelliSense even further by improving the performance and the accuracy of the
items shown in IntelliSense.
To see how the actual page works, and how it accesses the web service, take a look at the code in the
block.
The first code you need to look at is the helloWorld method:
function helloWorld()
{
var yourName = document.getElementById('YourName').value;
NameService.HelloWorld(yourName, helloWorldCallback);
}
First, this code gets a reference to the text box you created earlier. You then access its value property
to get the name the user entered.
This name is then sent to the web service method HelloWorld with the following code:
NameService.HelloWorld(yourName, helloWorldCallback);
The first argument of the call to HelloWorld is the argument that the web service method expects:
a string holding your name. The second argument, helloWorldCallback, is a reference to another
JavaScript method that is triggered when the service returns the result. By design, the call to the web