Head Rush Ajax

you’re on your way 4

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xml requests and responses

Filling that XML prescription

Trying to come up with a data format that works for the server, that the browser

understands, and that won’t have to change if Katie adds another product line or changes

the order of items on her report... that’s not so easy.

Luckily for us, Dr. Zigmund (as well as that rather impatient girl on the last page) seems

to have a solution: XML, the extensible markup language. Using XML, we can come up

with a simple response format that is clear, and contains all three updated sales totals.

Q:

What’s so great about XML?

A: The biggest thing going for XML

is that it’s a recognized standard. Some

folks at the World Wide Web Consortium

(or the W3C for short) define what makes

XML, well, XML. And since most people

agree to abide by the W3C standard,

browsers, servers, and programs like PHP

scripts can all use XML without wondering

what a bracket or a semicolon means.

Q:

I still don’t see why it’s so bad

to just make up our own data format.

Wouldn’t that be easier?

a: It might seem that way, but

proprietary data formats—formats that

you make up for your own use—can

really cause a lot of problems. If you

don’t document them, people forget

how they work. Even worse, some of

the characters you might use, like a

semicolon or comma, can have more than

one meaning, and they make the format

confusing to programmers.

Q:

I g ...