AJAX calls and Rich Internet Applications

Question

I am confused with the definition of Rich Internet Applications and AJAX calls.

As far as I understood every application which needs some executions in client-side will be considered RIA. So, this way, this website should be considered RIA because if you hover your mouse on the left menu in the page a sub-menu will be shown while there is no communication to the web server (and no change in the URL.) Also, if you right-click on the page and check out the page source, none of the elements inside that sub-menu exist on the page. But, when you right-click and hit the inspect element option you will find all those elements.

• Why do these elements exist in the DOM representation of the page while they don't exist on the HTML representation of the page?
• Should we consider such a execution an AJAX call? (As far as I understood the browser loads an AJAX engine when it loads a page, so every request will be issued to this engine, some of them will be handled on client-side while the others should be sent to the web server. So, would it be true to consider such a execution an AJAX calls which has been handled by AJAX engine in client-side?)
• What is the exact way of identifying a RIA? (there might be applications in which some JavaScript functions is used only to change the colour of the page for example. Should we consider such an application a RIA?)

Answer 1

Why do these elements exist in the DOM representation of the page while they don't exist on the HTML representation of the page?

Because the DOM can be manipulated with JavaScript.

Should we consider such a execution an AJAX call?

No. That's entirely achievable without making additional HTTP requests.

What is the exact way of identifying a RIA?

It's a fuzzy marketing term, not something with a strict technical definition. "Exact" doesn't come into it.