Head Rush Ajax

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145

asynchronous applications

Building an Ajax-powered coffee maker

Two coffee makers...

...and a whole ofce of caffeine addicts.

As the ofcial “coffee pot manager,” it’s your job to make sure that the caffeine

needs of your ofcemates are met... and quickly, at that. All your mates are

caffeine addicts, and they get a bit testy if there’s no fresh coffee on hand. Good

thing that there are two coffee makers; even if one order is being brewed, your

co-workers can place another order, and have it lled by the second coffee maker.

You’re going to build an Ajax application to allow

your co-workers to order their coffee online.

You don’t want anyone coming after you with empty coffee cups, so let’s write an

Ajax application for ordering coffee and keeping track of the status of both coffee

makers. Here’s what it will look like:

Here’s the second coffee

maker. If an order is brewing

in coffee maker #1, this

coffee maker will handle any

additional orders. Just like

coffee maker #1, it takes a

little time to brew a cup.

This is the main

coffee maker. Anytime

an order is placed, and

no coffee is brewing,

this coffee maker

handles the order. It

takes a little time to

brew a cup, though,

and the coffee maker

can only brew one cup

at a time.

Here’s where you place

your order. You enter

your name, the size of

the cup you want, and

what type of beverage

you’re interested in. ...