Posted by Andy Dingley on 06/23/83 11:39

On Thu, 09 Feb 2006 18:46:16 GMT, "Noozer" <dont.spam@me.here> wrote:

>OK, I'm at a loss here... I've spent some time on Google and Wikipedia and
>still don't understand just what Ajax is...

Your google fu is extremely weak then.

Read the excellent "Ajax in Action"
<http://www.amazon.com/gp/product/1932394613/codesmiths-20>

>Just what is Ajax?

It's an enabling paradigm shift underlying the Web2.0 technology
platform, silly!

>Is it just a "way" to code a webpage? Is it a different
>language, like VB.Net or Java?

No, absolutely not. Ajax is something that has been done regularly
since 1999 or so, built by assembling existing tools. Then it was
rounded up, tidied up, had its nose wiped and a book or two written
about it.

>Does anyone have any examples of what IS and what ISN'T Ajax? (Like a CSS
>comparison of a table layout vs. a CSS layout)

Think of an interactive form-filling task on the web, with an address
fill-in.

Old style:

User requests page.
Server sends page. Page is very big.
User selects State. Can't select County
User clicks to send page.
Server returns page with county list added for that state.
User realises they'd selected the wrong state and has to do it again.
User gets bored.

Ajax style:

User requests page.
Server sends page. Page is small.
User selects State.
Page uses Ajax to load county list while the user is on the same page.
User selects county.
Page calculates shipping costs to that county, by querying the post
office's server and UPS's server, then offering the best deal to the
user.
(User still hasn't had to submit a page to the server and wait for its
return yet)


How it does it is that it breaks the old HTML dependence on HTTP, and a
single "get page, submit page, get page, submit page" sequence. Bits of
JavaScript code and a component that can retrieve data (usually in XML)
by doing HTTP from within the same page are used. These allow the page
to get or submit snippets of data all without having to submit the main
page and wait for it to return.

>...and as an aside (and barely related) question, how about XML? I though it
>was just another markup language

It's really a low-level tool for building high-level markup languages.
These days it's the only game in town for that level.

>but I'm being told to stop using ASP and
>start using XML for my database apps.

That's a nonsensical statement. ASP, XML and a database are all
different things. XML has sometimes been used as a database, but it's
very bad at it.

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