RIA erra was annouced several years ago by companies like Adobe, Microsoft and Sun. Those companies had special software “fixtures” that move web behind static HTML. Flash player, Silverlight or JavaFX carried promise of more interactive future.
The only problem was that technologies like Flash Player and Silverlight were under control of companies. Yes, there were a lot of things that you could do with RIA tools. Building video player, complex enterprise apps and so on.
Adobe took even further step and made this technology available for Linux community. Unfortunately some managers took measures and decided that they won’t ship Eclipse based plugin for Linux and as a result this led company to cancelling support for Linux in Adobe AIR. The glorious promise of one code multiple platform was broken.
Flex/Flash/AIR and Silverlight are very advanced technology. They can do a lot. The price for that is hidden in their complexity. The web learned from mistakes of those technologies.
It happens that when you write code for the first time then you make a lot of mistakes. Once you do it again you can make it even more efficient. RIA era was great starting point for open technologies that we have today.
I would like to add further points to Flex, because I invested huge amount of my time into this technology. Flex is great piece of technology art. There is no question about that. Flex is even open source. Unfortunately it is complex. Complexity is good when you want to sell enterprise software. Let me formulate it in other way: It was good when you wanted to sell enterprise software. Complexity of projects were blocking Innovation. Take jQuery do some fancy stuff in 5 minutes and you won’t be able to do it in Flex in 4 days.
The primary trap of Flex was one big untrimmed framework. Adobe found out that Flex 3 is too big to fit on mobile devices and therefore Flex 4.5 has completely different architecture. It is so different that it took several days or weeks to port application. That is expensive and result is questionable. My advice is do not try to port app to Flex 4. Write a new one.
The last hope for Adobe Flash player was to promise something great. They promised wonders of 3D in Flash player “soon” at Adobe MAX 2010. Today is summer 2011. No 3D was launched in official version of Flash Player. Meanwhile WebGL and Canvas took off. Open technologies are taking over the ground of 3D and people are doing real creative stuff with great performance even without Flash.
Adobe focused Flex 4.5 on mobile development. I doubt that it was right step how they did it. In order to meet the promise of mobility they had to broke a lot of backward compatibility stuff and to be honest you have to rebuild apps from the scratch again. Another problem is that many good Flex/RIA developers left Adobe in last months. It’s a big challenge for Flex team to keep the ball rolling. I wish them good luck.
I do not regret time invested into Adobe technologies. It taught me a lot. The only thing that I saw as a weak point of Adobe is communication with community. Voices from Linux community were overlooked for many years. Even minor bugfixes took 2 years to implement. Adobe was not able to off-load this development and testing to community. jQuery and other JavaScript frameworks did this in much better fashion.
As far as I understand actual situation Adobe is now moving toward more “safer” enterprise world. Adobe bought Day software and other companies that are focused on enterprise world. But that is different story.
To tell long story short: This is the end of the RIA era as we know it. There are new challenges 
Your desktop environment from Linux and Windows will merge in seamless way:
