Head Rush Ajax

358

what’s the goal

Chapter 6

XML is a specication that the World Wide Web

Consortium (W3C) works and agrees on. That

means that when you say XML, everyone knows

what you mean. But XML is really a

metalanguage: a language for dening other

languages. So, in the Boards app, you used XML,

but you dened your own elements that had names

that worked well with the Boards ‘R’ Us app.

If you wanted to update Break Neck

Pizza’s server to return XML, you’d

probably use different elements, perhaps

with names like <deliveryTime> and

<orderConrmation>. The code on your

server and the JavaScript code that you write must

use the same element names, or nothing is going

to work.

You keep saying XML is better because it’s not

proprietary, and that it’s a “standard.” But that

Boards ‘R’ Us XML uses elements like <boardsSold>

and <bootsSold>. How is that standard? I mean, who

else

is gonna use those elements?

XML is a standard...

...but how you use it isn’t.

XML

This is XML. It denes what an element

is, what an attribute is, and how things

like angle brackets, < and >, are supposed

to be used. XML is a metalanguage.

<

>

XML is

a meta-

language:

it defines

other XML

languages.

you’re on your way 4

359

xml requests and responses

<?xml version=”1.0” encoding=”utf-8”?>

<totals>

<boards-sold>1710</boards-sold>

<boot ...