I'm bearish on Rails because its maintainers don't want it to just be an API. The fight to become the best backend API is much different than the fight to become the best html server. Rails isn't even participating in the fight. Rails has a lot of cruft not needed in an API, Sinatra or Express feel much better for that.
Rails isn't even participating in the fight
Rails became popular because with it developers had the ability to cut down on soul-sucking activities in their day to day jobs, like building yet another authorization system, or yet another admin. That some people ran with it and scaled it to its limits, that's only because they felt in love with its ease of getting things done.
That's its main advantage. When it comes to getting things done, there's no better alternative.
The fight to become the best backend API
is much different than the fight to become the
best html server.
So you see, there is no fight. That fight was won long ago by the JVM and the frameworks that run on top of it. Every big website on the web right now (except Microsoft-stuff), runs either on top of the JVM or with custom-baked solutions written in C/C++.
That didn't stop people from building cool stuff on top of PHP, or Rails, or Django, or every other platform that brought instant gratification, but that's another point entirely and we are talking about "battles" here.
Can you define big? I've worked on some big sites that used MRI ruby for APIs and we served a ton of traffic with strict SLAs for a max of 250ms at the 99th percentile and things like that.
I think by big that's a code word for enterprise.
The big sites you have worked on are comparatively small if Ruby is backing the show. That's not to take away from the ton of traffic that you guys were able to serve; it's just that there are few enterprise level Ruby backed sites running these days.
Github, I believe is one, but lately I've been getting the "unicorn is angry" icon when viewing repositories, so I wonder about scalability issues. For the record, I have never, ever seen a "unicorn is angry" icon on Twitter. Maybe switching to the JVM got rid of all the magic ;-)
"The big sites you have worked on are comparatively small if Ruby is backing the show."
That's a big assumption. You have no idea who I am or what I've worked on. One of the sites I worked on was yellowpages.com. That's a top 1000 site, but even that doesn't tell the full story. When I was there we were serving ads for most requests to bing maps. Do you consider bing maps comparatively small?
I currently work for disney who runs espn.go.com. The person sitting next to me right now worked on espn.go.com before she transferred to my group. I can assure you that espn.go.com could easily be served with ruby instead of java.
I'm questioning a couple of specific claims made by bad_user. That all big sites use the JVM or c/c++ or .net. I think that is false, or the definition of "big" is so narrow as to be meaningless for 99.9% of programmers. I'm also questioning the claim that the best backend is the one that is the fastest. I'd argue that the best backend is the one that is fast enough and the cheapest, wouldn't you agree? As I mentioned before, I was working on an api that served requests for bing maps with a very tight SLA. We ran it on MRI ruby, and we met the SLA.
Here's something that people often forget, you can put things like varnish in front of your API. This doesn't work for everyone, but if you're API is easily cached, then you shouldn't have any problems scaling it even if you're using a language like MRI ruby which has a GIL.
I beg your pardon, but... what?! Out of the box, Rails has none of this. Rails is almost a meta-framework. Honestly taking your two examples: Devise is horribly complicated and the half-dozen admin frameworks that had a hard time crossing the 3.x line (which is not encouraging for the future) are either generators, downright incomplete enough to be useful outside of a hello world, or frameworks in themselves. I defy anyone beginning with Rails to set up Devise and an admin system in less than half a day, let alone an hour. I'm not trying to pick up a fight, but anecdotally compare this to Django, where setting up both auth and admin is largely under 30min for a newcomer, easy, with ample possibilities left ahead.
So although Rails helps a lot in various areas (like resource routing, respond_to/with), but it still ends up being soul-sucking in numerous others where you have to either delve into needlessly complicated stuff or implement it yourself.
This is a false equivalence IMO. With rails i spend far less time on incidental complexity than I do with anything else I've tried.
What does that make Wikipedia (PHP), Craiglist (Perl), Wordpress (PHP) and Youtube (Python[1]) ?
[1]: http://www.quora.com/Is-YouTube-still-written-in-Python
Wordpress is an interesting one, I wonder if they aren't doing some C++ pre-compilation a la Facebook's HipHop? Maybe not, WP is pretty light code-wise (compared to the slow, bloated dog that is Drupal), and for the most part personal blogging sites are not handling Twitter level bandwidth last I checked.
@bad_user is a cool thinker @icebraining, no hot headedness to be found, he's just stating the facts in regard to industry trends for enterprise level applications: it's an M$ and JVM world.