Question

Is there a specific metric which a system should meet to be considered/classified as real-time web application or a near- real time web application?

When I see a non-functional requirement for a system on which I am working which states the solution shall return data in real time/near real time. I understand the definition of the terms (as found http://en.wikipedia.org/wiki/Near_real-time), but I was wondering if there were standards like one might find for an application UI (example: Gnome recommendations
http://developer.gnome.org/hig-book/3.5/feedback-response-times.html.en) for expectations of near real time in a web application.

This is a variant of another question:
Define realtime on the web for business

Answer 1

Real-time computing has nothing to do with performance, but rather the guarantee that an event can be completed in a set amount of time. Real-time requirements have implications throughout the architecture from CPU scheduling algorithms to the operating system all the way to the application being built.

Real-time requirements are specified in terms of the amount of time in which an operation must be completed. Again, this must be guarantee and systems will often fault when the deadline is not met (this is not expected).

See also What constitutes 'real time'