Today there is tons of AJAX implementations but if you look closer you'll find three categories :
For every implementation its best usage, performance and negative
points, difficult to see them all here one by one, but most important
is how to find the best framework for your application or just use a
JavaScript based implementation. This depend on the application itself,
on the developer's experience, and frameworks capabilities. But with
this large choice of implementations it's in the same time difficult to
decide and easy to find exactly what you are looking for.
AJAX, the standard
There is updates on W3C work about XMLHttpRequest, but you'll find a post prior to this talking in details about the W3C Working Draft of the XMLHttpRequest Object which have been released on December 27, 2006. This is in addition to the work of the OpenAjax Alliance lead by IBM and which include most important actors in Ajax technology. Open AJAX alliance have released a White Paper where you can find more about the technology and the activity of the group.
AJAX
involve the web client, JavaScript and server-side capabilities
together, the reason why many organizations and companies are involved
to make a standard for AJAX.
AJAX and Flash
I agree with many experts that AJAX have lots to learn from flash for rich media capabilities, but in the same time I find that AJAX
have many advantages especially that you won't have to download a
client, there is no problems of version compatibilities, the necessary
for the end-user already exist : a browser with Javascript support.
I was looking at phpmagazine's stats for 2006 and noticed for Flash
the different versions used over the year. Version goes from 7.0 to
9.0, so if I have flash website wich require Flash 9 for example there
will be 82% of visitors who'll have to update their clients.
