Separate REST JSON API server and client? [closed]
I'm about to create a bunch of web apps from scratch. (See http://50pop.com/code for overview.) I'd like for them to be able to be accessed from many different clients: front-end websites, smartphone apps, backend webservices, etc. So I really want a JSON REST API for each one.
Also, I prefer working on the back-end, so I daydream of me keeping my focus purely on the API, and hiring someone else to make the front-end UI, whether a website, iPhone, Android, or other app.
Please help me decide which approach I should take:
TOGETHER IN RAILS
Make a very standard Rails web-app. In the controller, do the respond_with switch, to serve either JSON or HTML. The JSON response is then my API.
Pro: Lots of precedent. Great standards & many examples of doing things this way.
Con: Don't necessarily want API to be same as web app. Don't like if/then respond_with switch approach. Mixing two very different things (UI + API).
REST SERVER + JAVASCRIPT-HEAVY CLIENT
Make a JSON-only REST API server. Use Backbone or Ember.js for client-side JavaScript to access API directly, displaying templates in browser.
Pro: I love the separation of API & client. Smart people say this is the way to go. Great in theory. Seems cutting-edge and exciting.
Con: Not much precedent. Not many examples of this done well. Public examples (twitter.com) feel sluggish & are even switching away from this approach.
REST SERVER + SERVER-SIDE HTML CLIENT
Make a JSON-only REST API server. Make a basic HTML website client, that accesses the REST API only. Less client-side JavaScript.
Pro: I love the separation of API & client. But serving plain HTML5 is quite foolproof & not client-intensive.
Con: Not much precedent. Not many examples of this done well. Frameworks don't support this as well. Not sure how to approach it.
Especially looking for advice from experience, not just in-theory.
Solution 1:
At Boundless, we've gone deep with option #2 and rolled it out to thousands of students. Our server is a JSON REST API (Scala + MongoDB), and all of our client code is served straight out of CloudFront (ie: www.boundless.com is just an alias for CloudFront).
Pros:
- Cutting-edge/exciting
- A lot of bang for your buck: API gives you basis for your own web client, mobile clients, 3rd party access, etc.
- exceedingly fast site loading / page transitions
Cons:
- Not SEO friendly/ready without a lot more work.
- Requires top-notch web front-end folk who are ready to cope w/ the reality of a site experience that is 70% javascript and what that means.
I do think this is the future of all web-apps.
Some thoughts for the web front end folks (which is where all the new-ness/challenge is given this architecture):
- CoffeeScript. Much easier to produce high-quality code.
- Backbone. Great way to organize your logic, and active community.
- HAMLC. Haml + CoffeeScript templates => JS.
- SASS
We've built a harness for our front-end development called 'Spar' (Single Page App Rocketship) which is effectively the asset pipeline from Rails tuned for single page app development. We'll be open-sourcing within the next couple of weeks on our github page, along with a blog post explaining how to use it and overall architecture in greater detail.
UPDATE:
With respect to people's concerns with Backbone, I think they are over-rated. Backbone is far more an organizational principle than it is a deep framework. Twitter's site itself is a giant beast of Javascript covering every corner-case across millions of users & legacy browsers, while loading tweets real-time, garbage collect, display lots of multimedia, etc. Of all the 'pure' js sites I've seen, Twitter is the odd one out. There have been many impressively complicated apps delivered via JS that fare very well.
And your choice of architecture depends entirely on your goals. If you are looking for the fastest way to support multiple clients and have access to good front-end talent, investing in a standalone API is a great way to go.
Solution 2:
Very well asked. +1. For sure, this is future useful reference for me. Also @Aaron and others added value to discussion. Like Ruby, this question is equally applicable to other programming environments.
I have used the first two options. First one for numerous applications and second one for my open source project Cowoop
Option 1
This one is no doubt the most popular one. But I find implementation are very much http-ish. Every API's initial code goes in dealing with request object. So API code is more than pure ruby/python/other language code.
Option 2
I always loved this.
This option also implies that HTML is not runtime generated on server. This is how option 2 is different from option 3. But are build as static html using a build script. When loaded on client side these HTML would call API server as JS API client.
Separation of concerns is great advantage. And very much to your liking (and mine) backend experts implement backend APIs, test them easily like usual language code without worrying about framework/ http request code.
This really is not as difficult as it sounds on frontend side. Do API calls and resulting data (mostly json) is available to your client side template or MVC.
Less server side processing. It means you may go for commodity hardware/ less expensive server.
Easier to test layers independently, easier to generate API docs.
It does have some downsides.
Many developers find this over engineered and hard to understand. So chances are that architecture may get criticized.
i18n/l10n is hard. Since HTML is essentially generated build time are static, one needs multiple builds per supported language (which isn't necessarily a bad thing). But even with that you may have corner cases around l10n/i18n and need to be careful.
Option 3
Backend coding in this case must be same as second option. Most points for option 2 are applicable here as well.
Web pages are rendered runtime using server side templates. This makes i18n/l10n much easier with more established/accepted techniques. May be one less http call for some essential context needed for page rendering like user, language, currency etc. So server side processing is increased with rendering but possibly compensated by less http calls to API server.
Now that pages are server rendered on server, frontend is now more tied with programming environment. This might not be even a consideration for many applications.
Twitter case
As I understand, Twitter might does their initial page rendering on server but for page updates it still has some API calls and client side templates to manipulate DOM. So in such case you have double templates to maintain which adds some overhead and complexity. Not everyone can afford this option, unlike Twitter.
Our project Stack
I happen to use Python. I use JsonRPC 2.0 instead of REST. I suggest REST, though I like idea of JsonRPC for various reasons. I use below libraries. Somebody considering option 2/3 might find it useful.
- API Server: Python A fast web micro framework - Flask
- Frontend server: Nginx
- Client side MVC: Knockout.js
- Other relevant tools/libs:
- Jquery
- Accounting.js for money currency
- Webshim : Cross browser polyfill
- director: Client side routing
- sphc: HTML generation
My conclusion and recommendation
Option 3!.
All said, I have used option 2 successfully but now leaning towards option 3 for some simplicity. Generating static HTML pages with build script and serving them with one of ultra fast server that specialize in serving static pages is very tempting (Option 2).
Solution 3:
We opted for #2 when building gaug.es. I worked on the API (ruby, sinatra, etc.) and my business partner, Steve Smith, worked on the front-end (javascript client).
Pros:
Move quickly in parallel. If I worked ahead of Steve, I could keep creating APIs for new features. If he worked ahead of me, he could fake out the API very easily and build the UI.
API for free. Having open access to the data in your app is quickly becoming a standard feature. If you start with an API from the ground up, you get this for free.
Clean separation. It is better to think of your app as an API with clients. Sure, the first and most important client may be a web one, but it sets you up for easily creating other clients (iPhone, Android).
Cons:
- Backwards Compatibility. This is more related to an API than your direct question, but once your API is out there, you can't just break it or you break all your clients two. This doesn't mean you have to move slower, but it does mean you have to often make two things work at once. Adding on to the API or new fields is fine, but changing/removing shouldn't be done without versioning.
I can't think of anymore cons right now.
Conclusion: API + JS client is the way to go if you plan on releasing an API.
P.S. I would also recommend fully documenting your API before releasing it. The process of documenting Gaug.es API really helped us imp
http://get.gaug.es/documentation/api/