Take Microsoft Live Mail for example. It loads in everything at once – contacts, recently updated spaces, all sorts of things that you’re probably not directly interested in; however those things help useability (such as auto-complete when you’re typing in an email address). The initial download is slow, but subsequent requests are quick since Javascript and CSS is locally cached.

When I introduce AJAX into a site, I do so purely for useability reasons; to empower the technically-unsavvy to better manage the tools that are provided for them. Forcing AJAX upon users is a bad idea and should only be used to improve existing functionality; not to replace it entirely.

The reason so many sites use AJAX and are horrendously slow is they are coded by designers, not programmers, and they use monolithic libraries instead of optimized code. It’s a by-product of the whole 37signals/Rubyonrails philosophy, which is focused on being easy for the programmer and leaves little room to optimize. Not coincidentally, some of the worst AJAX offenders are RoR-powered sites.

Where everyone in the company can access them, including executives.

So that everyone in the world that works for that company can use the software as if it were a desktop application, but dont need it on their local machine, which cuts IT costs significantly.

So only one source will need to be fixed if a problem is presented, rather than 1254 different machines out of the 50,000 in the company.

TIBCO’s case studies are a few good examples of where an backbone set of db’s coupled with ajax interfaces can be extremely helpful.

Its just a way of removing a pageload – some people go overkill, but it has its uses.

Here’s 2 good user-interface improvement features of AJAX that immediately pop to mind:

> AJAX popups that can load in a layer over the normal page content. Great for a few things, but there’s lots of potential for this to be overused.

> Form usability (A good example is when you select a Country from a dropdown list, and if you select, say Canada, the next field becomes a “Select Province” option.

@doug gmail is one of the one’s I complain about, it always hangs and thats on every PC I use it on. I hate that back button doesn’t work. Those two apps are nice but how does using ajax help make the better?

@jeremey interesting but you could accomplish the same thing with some creative URL construction, robots and meta tag implementation and not lose the deep-linkability of the url.

Curious Matt has the only reason that attracts me in any way. Every other one seems better solved with non-ajax technology.

Classic HTML: You submit a button on a page and the page posts the information to another page that then renders.

Ajax: You submit a button on a page and the javascript posts the iformation to another page that sends the proper information back and renders it.

There’s really no difference. Ajax is simply a ‘buzzworthy’ term but it simply interacts through javascript how a page transition would.

As for speed, well-constructed Ajax should load much quicker and be less of a stress on your site if built efficiently. The reason is that you can manage ‘chunks’ of data rather than entire pages.

As for CSS – passing visual elements with Ajax should absolutely be a no-no. You should simply be passing back and forth the minimal data and forming it appropriately using styles. There’s a ’sister’ technology called AHAH that passes HTML back and forth – again, presentation should be separate from the data. Take a look at http://payraisecalculator.com and http://www.addressfix.com – both utilize Ajax but in a manner that makes it a better user experience.

Google Maps, Gmail, Yahoo Mail, and others are all constructed brilliantly with Ajax. I would add that there are great places to use Ajax and stupid places to use it. It’s only as good as its gains in Usability and efficiency.

Aside from Comment posting, I’ve really not seen any viability in utilizing a lot of Ajax on blogs.

Regards,
Doug