A nodejs stack makes more sense to me because the app itself is powered by JavaScript, not Ruby, and then I am truly decoupled from other languages. However, I can see why someone coming from Ruby would prefer Spar -- even Spine.app includes Sprockets support for Ruby devs.
There is a massive gap here, and with any framework that is purely client-side. Here's what you get if you serve html from the server:
* SEO. You can't crawl a page that loads purely over Javascript. Google has an API to allow access to ajaxed-in pages, but that means modifying you code to fit exactly what each crawler needs. Not going to happen.
* Better accessibility. Yes, some screen readers handle Javascript now, but many don't.
* Page performance. Time-to-usability on a page served by a server is several orders of magnitude faster than when you load javascript, then load data, then render the page. If the server can serve html, you can start using the page while the scripts load and initialize in the background.
If performance isn't a big deal, you want to make awkward hacks to force SEO to work, and you don't care about reaching all possible people? Build a single-page-app and nothing else.
I'm not saying don't make a single-page app; I'm saying be smart about it.
You've got two steps out of three - building an API and a single-page app. The missing middle step is building a second server side app that reads from that API (RESTful, right?) and bootstraps the page, which is built using language-agnostic templates like Mustache. Then, you load your Backbone/whatever JS on top, which takes over, and points at your api. It's easy to do with something like Node that can even share the same code to build pages.
SEO - True. There are many different strategies to deliver solid SEO results using technologies like Spar. You can use headless browsers to pre-render and deliver on-demand rendered content, if you know your URL space completely, you can pre-render all documents. Spar isn't an attempt to solve SEO for you, you may not even care if you are building a phone-gap app, for instance. So does that invalidate the technology?
Accessibility: I'm 100% behind accessibility, and if the compatible tricks don't work... do you still make your site accessible for IE3? No... screen- readers MUST catch up. We can all do what we can to help, but shouldn't engineer for the past, which is an orthogonal concern from accessibile technology choices.
Page-performance - I'll challenge the several orders of magnitude claim, we've seen incredible performance w/ the approach, and best-case you're only talking about first-page speed, even ceding that it becomes a much different story later on... and if you're building an 'app' thats a big difference.
> do you still make your site accessible for IE3? No...
I subscribe to the ideas behind progressive enhancement, so I don't have to make that choice. An application can be built that works everywhere, for every technology, with little development overhead (and in my experience, the lowest-experience-first PE approach generally leads to better code anyway.) This isn't just theory - I've done it with apps large and small, and it works. I highly suggest http://filamentgroup.com/dwpe/ to find out more.
> best-case you're only talking about first-page speed
I'd also argue that that's what matters most to visitors - numerous studies show that there's a dropoff as that first page takes longer to load. Here we have the difference between loading a page, being useful, and then loading scripts vs loading an (empty, so faster) page, load libraries, load templates, then load data, then push the template to the screen. Additionally, if you're doing server rendering, you can probably cache that first hit at the web server level and avoid even hitting the web application at all.
The difference won't matter if you have a tiny app, so you don't have much js to download - but it will make a big difference if you have anything reasonably-sized.
If im understanding the OP they have created some tools for helping to create SPA web apps, not solve SEO.
turning ajacksifieds arugement around, I don't see many guys on the SEO threads complaining that the keyword stuffing needs more SPA.
How nice and friendly of you.
