Active resource in rails
 This is a powerful feature of rails to communicate between two models in two different application running in two different server. ActiveResource:Base is the main class for mapping RESTful resources as models in a Rails application. Active Resource objects represent your RESTful resources as manipulatable Ruby objects. To map resources to Ruby objects, Active Resource  only needs a class name that corresponds to the resource name (e.g., the class User maps to the resources Products, very similarly to Active Record) and a site value, which holds the URI of the resources.   class User < ActiveResource::Base    self.site = "http://api.products.com:3000/"  end    In order to access products.com controller you need to send the json response like i am going to call the index action so we need to write :-  def index  @products = Product.all  respond_to do |format|    format.json { render :json => @products}  end end   Now the User class is mapped to RESTful resources located...