Head Rush Ajax

38

Chapter 1

To gure out what’s going on, we’re going to have to step back a bit, and

think about web applications in general. When you think about a web

appl, you probably think about an HTML page, some JavaScript code, a

bit of CSS for style, and maybe a web server running some scripts or a

servlet. All these pieces work together, like this:

How we see web apps...

JavaScript

Request

Web Server

Response

<html>

.

.

.

</html>

h1, h2 {

fon

col

}

p {

HTML

CSS

You use HTML to say

what a web page is...

...and CSS

to say how

the page

should look.

The HTML and CSS get

combined into what we actually

see—the web page.

You use JavaScript to say

what a web page does.

The web server waits on

requests, and then sends

data back to your web page.

But there’s more going on than meets the eye...

PHP scripts, Java servlets,

Ruby programs, and other

server-side components.

<script>

var request...

function foo()

{

...

}

</script>

a simplistic view of web applications

you’re on your way 4

39

next generation applications

?

It’s time to test those higher-order thinking skills. There’s an important

character in the Ajax play that you haven’t met yet, and he’s ready to make

his grand entrance. See if you can upstage this new character by guring

out who he is before you turn the page. We’ve managed to collect a few

quotes from the ...