How do I build an API for my Rails app, so that multiple sites can share one database?

I have a Rails application that right now 开发者_如何学JAVAis pretty standard: Heroku/PostgreSQL backend, users go directly to my site to update data, there's no mobile app or anything. We're going to start licensing out the tech to other companies, so that different versions of the interface live on company1.mywebsite.com, company2.mywebsite.com, etc, where all of these interfaces share the same database.

I want some advice on how to go about building this. Do I create a separate Rails app for company1, company2, etc (with a lot of redundant code) and then set up each of them with API keys to query my master app, using its RESTful routes?

Any tutorials to point me to would be great as well.

I recommend you the book Service Oriented Design with Ruby and Rails, by Paul Dix. It has a lot of info about the kind of system that you want to build.

To answer your question:

• Build an API server. It serves a JSON – for example – RESTful interface.

  api.mydomain/client1/users.json
  

• Build a frontend server. It consume the API service – using typhoeus for example – and serves the final pages. It uses a subdomain or domain name for identification of different clients.

  client1.mydomain/users
  

We have a similar "platform".

What we did:

1. build a master API app (REST + Push)
2. build a core plugin for rails which has all the shared code
3. build a separate rails app for each client which has all the client specific code

We are using this setup for 3 years now and I'm pretty happy with it.