There are many things that make up a RIA today. I posted last week about Interactive vs Internet, and I think it's played out enough. Personally my conclusion is to let the "I" be silent, and it could be "Information, Interactive, Internet, Interface, Idiocy" etc. "I" of the beholder if you will.
This blog is what I'd classify a website, but one could also argue that it has a degree of "application" associated to it, in that think of the context of use. You visit the site, you read my posts, you decide to move on or leave a comment - if you will - you reply.
Now where have I seen that methodology before. Oh yes, email.
What are the differences between Email Messages and Blogs, especially as more and more agents popup around the globe in helping you manage all your RSS feeds. Yet, at the grass roots of them all, they are simply websites?
What is RIA today, and where is it going. Already folks from the competition are talking about branded applications being accepted as RIA? (*shrug*)
Website or Application? show me the distinct difference between Flickr and Picnik.com? once you do, compare the results against Nike+ while at the same time compare to <insert your favourite RIA here>.
Confused? I know I am and I've been in this space since 1999. I must be getting old and all this new RIA fashion seems to be skewing my understanding of a website.
Is it a case of "If it has a runtime, it's classified as RIA until proven otherwise" or is it even possible today to show a definitive split between website and application. That being said, the Rich part of the discussion will be easy, as it's simply a case of underpinning the user experience quality and degrees of such.
Overall, I doubt there will be a true definitive answer suffice to say, the term is slowly starting to crack in places and in a very subtle way, being bent to suite different agenda's. In saying this, my conclusion is that it's fast becoming a term that lacks maturity, governance and is practically the same as other terms like CMS, CRM, ERP, SOA etc.
It's what you make of it, and any whom oppose your belief is both right and wrong. It will just come down to your debating skills as to which of the two will ultimately win out.
In the end, it's all a website, just with different grades of user experience housed within an aggregated view over different layers of services.