OAuth2

• Get familiar with OmniAuth by Intridea: http://github.com/intridea/omniauth. Read about OAuth2.
• Obtain client_id and client_secret for your app from Exvo.
• Install exvo-auth gem or add it to your Gemfile.

Configure middleware.

In Rails, the relevant lines could look like this:

ExvoAuth::Config.client_id     = "foo"
ExvoAuth::Config.client_secret = "bar"
ExvoAuth::Config.debug         = true # dumps all HTTP traffic to STDERR, useful during development.
config.middleware.use ExvoAuth::Middleware

Add routes.

The following comes from Rails config/routes.rb file:

match "/auth/failure"                  => "sessions#failure"
match "/auth/interactive/callback"     => "sessions#create"
match "/auth/non_interactive/callback" => "sessions#create" # only if you use json-based login
match "/sign_out"                      => "sessions#destroy"

Failure url is called whenever there's a failure (d'oh). You can have separate callbacks for interactive and non-interactive callback routes but you can also route both callbacks to the same controller method like shown above.

Include controller helpers into your application controller.

include ExvoAuth::Controllers::Rails (or Merb)

Implement a sessions controller.

Sample implementation (Rails):

class SessionsController < ApplicationController
  def create
    sign_in_and_redirect!
  end

  def destroy
    sign_out_and_redirect!
  end

  def failure
    render :text => "Sorry!"
  end
end

Implement #find_or_create_user_by_uid(uid) in your Application Controller.

This method will be called by #current_user. Previously we did this in sessions_controller but since the sharing sessions changes this controller will not be used in most cases because the session comes from another app through a shared cookie. This method should find user by uid or create it. Additional info (emails, etc) can be obtained using auth api (/users/uid.json path).

In short: you get params[:auth]. Do what you want to do with it: store the data, create session, etc.

Sign up and sign in paths for use in links.

sign in path:                       "/auth/interactive"
sign up path:                       "/auth/interactive?x_sign_up=true" # this is OAuth2 custom param
sign in path with a return address: "/auth/interactive?state=url"      # using OAuth2 state param

You have a handy methods available in controllers (and views in Rails): sign_in_path and sign_up_path.

Read the source, there are few features not mentioned in this README.

Inter-Application Communication

You need to have "App Authorization" created by Exvo first. Contact us and provide following details:

• consumer_id - Id of an app that will be a consumer (this is you)
• provider_id - Id of the provider app
• scope - The tag associated with the api you want to use in the provider app

Consumer side

consumer = ExvoAuth::Autonomous::Consumer.new(
  :app_id => "this is client_id of the app you want to connect to"
)
consumer.get(*args) - interface is exactly the same like in HTTParty. All http methods are available (post, put, delete, head, options).

Provider side

See #authenticate_app_in_scope!(scope) method in ExvoAuth::Controllers::Rails (or Merb). This method lets you create a before filter. Scopes are used by providing app to check if a given consuming app should have access to a given resource inside a scope. If scopes are empty, then provider app should not present any resources to consumer.

Example of the before filter for provider controller:

before_filter {|c| c.authenticate_app_in_scope!("payments") }

In provider controller which is just a fancy name for API controller you can use #current_app_id method to get the app_id of the app connecting.

Dejavu - replay non-GET requests after authentication redirects

Limitations:

• doesn't work with file uploads
• all request params become query params when replayed