ASP.NET AJAX :JSON Infrastructure

The growing use of out-of-band calls in Web applications poses a new
issue—moving more and more complex data around. It's not a mere
serialization issue for which the .NET Framework and other
platform-specific frameworks have a ready-made solution. The
serialization involved with out-of-band calls is not just
cross-platform; it also involves distinct tiers and radically
different tools and languages. With out-of-band calls, you move data
from a client to a server and back. But the client is a browser (if
not a mobile device), and JavaScript is the native format of data.
The server is a Web server hosted on a variety of hardware/software
platforms and running a specific Web application framework.

JSON is the emerging technology for passing structured data across the
Web. It is a data interchange format and is fully described at
http://www.json.org. Relatively easy to read for
humans and to parse and generate for machines, JSON describes data
using two universal data structures—collections and array—that are
supported in one way or another by most
modern programming languages and class libraries.

JSON is a text format that is completely language independent,
although it relies heavily on a number of conventions inherited from
the C family of languages.

The JSON client infrastructure can serialize a JavaScript object to an
interchange format and send it over the wire to a server-side
receiver. The platform-specific receiver will parse the data stream to
build a platform-specific object. Likewise, the JSON server
infrastructure can take any platform-specific object and serialize to
an interchange format. Back on the client, the data stream is promptly
transformed in a JavaScript object. As far as the .NET Framework and
ASP.NET are concerned, a bit of reflection is used to examine the
internal structure of classes and create proper JavaScript wrappers.

Virtually all AJAX-based frameworks implement a JSON infrastructure.
ASP.NET AJAX is no exception.