Datasheet

Chapter 1: AJAX Technologies

Things are pretty simple on the client side, as you can see in the following code fragment from Listing 1-4 :

var response = request.responseText;

eval(“var employee=” + response + “;”);

This simply calls the eval JavaScript function to deserialize an employee object in the JSON string

received from the server. As you can see, the messy XML deserialization code presented in Listing 1-3 is

all gone and replaced with a simple call into the

eval JavaScript function. However, this simplicity

comes with a price. Because the

eval JavaScript function basically trusts the scripts that it runs, it intro-

duces serious security issues. This is not a problem in this example because the JSON representation is

coming from a trusted server. However, in general, you must be very careful about what gets passed

into

eval .

ASP.NET AJAX

The ASP.NET AJAX framework brings to the world of AJAX-enabled Web application development

what ASP.NET and the .NET Framework brought to the world of server-side Web application

development over the past few years. The biggest advantage of ASP.NET over the earlier server-side

Web development technologies such as the classic ASP is that you get to program in the .NET Frame-

work, which provides the following benefits among many others:

❑ The .NET Framework is a full-fledged, object-oriented framework that enables you to take full

advantage of all the well-known benefits of object-oriented programming such as classes, inter-

faces, namespaces, polymorphism, inheritance, and the like.

❑ The .NET Framework comes with a large set of managed classes with convenient methods,

properties, and events that save you from having to write lots of infrastructure and generic code

that have nothing to do with the specifics of your application.

❑ The .NET Framework includes a full-fledged typing and type-reflection system that enables you

to perform runtime type inspections, discoveries, instantiations, invocations, and the like.

❑ The .NET Framework provides you with groundbreaking facilities and capabilities such as the

following:

❑ Application lifecycle and its events: The HttpApplication object that represents an ASP.NET

application goes through a set of steps or phases collectively known as the application life-

cycle. This object raises events before and/or after each lifecycle phase to allow you to cus-

tomize the application lifecycle.

❑ Page lifecycle and its events: Every ASP.NET page goes through a set of steps or phases

collectively known as the page lifecycle. The

Page object that represents the ASP.NET page

raises events before and/or after each lifecycle phase to allow you to customize the page

lifecycle.

❑ Server controls: Server controls enable you to program against the underlying markup

using the .NET Framework and its rich, object-oriented class library. This gives you the

same programming experience as these server controls desktop counterparts provide.

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