Routing for an API with subdomains - ruby-on-rails

Question

I have written a simple API but something feels wrong about the routes and the APIs. Its my first time am writing an API and just a few months writing ROR code. Take a look at the code below and help me straighten it!!
I wish the API to respond to requests like https://api.xxxxx.com/v1/xml?username=u_name&password=passwd& to=xxxxx&from=xxxx&message=text
The subdomain does not seem to be working either;
Routes
namespace :api, :path => "", constraints: {subdomain: 'api'} do
namespace :v1 do
namespace :json, defaults: {format: :json} do
resources :messages
resources :balance
end
namespace :xml, defaults: {format: :xml} do
resources :messages
resources :balance
end
end
end
These are the controllers for the json API
Messages Controller:
class Api::V1::Json::MessagesController < ApplicationController
before_filter :authenticate
def show
end
def create
#user = current_user
#message = Message.new(params[:message])
if #message.save
MessageWorker.perform_async(#message.id, lists, current_user.id)
render json: {status: "success", to: #message.count, from: #message.from,
balance: #user.balance, message: #message.message},
time: #message.created_at}
else
render status: 400
end
end
def authenticate
authenticate_or_request_with_http_basic do |username,password|
resource = User.find_by_email(username)
if resource.valid_password?(password)
sign_in :user, resource
end
end
end
end
Balance Controller:
class Api::V1::Json::BalanceController < ApplicationController
before_filter :authenticate
def show
#balance = current_user.balance
render json: {user: current_user.name.titleize, balance: "#{current_user.currency}: #{#balance}"}
end
def authenticate
authenticate_or_request_with_http_basic do |username,password|
resource = User.find_by_email(username)
if resource.valid_password?(password)
sign_in :user, resource
end
end
end
end

Answer 1

Do:
constraints subdomain: 'api' do
scope module: :api do
namespace :v1 do
You'd rather not namespace json or xml, it makes no sense: the same controllers should handle both request, just a matter of format.
Rails makes it really easy with respond_to