login_controller.rb

require 'openid'
require 'openid/consumer'
require "openid/store/filesystem"
require 'openid/extensions/sreg'

class LoginController < ApplicationController
  def create
    response = openid_consumer.begin(params[:openid_url])
    sregreq = ::OpenID::SReg::Request.new
    sregreq.request_fields(["email"], true)
    sregreq.request_fields(["fullname", "nickname"], false)
    response.add_extension(sregreq)

    redirect_to response.redirect_url(root_url, login_complete_url)
  rescue Timeout::Error
    flash.now[:error] = "OpenID request timed out."
    render :action => "new"
  rescue OpenID::DiscoveryFailure
    flash.now[:error] = "Couldn't find an OpenID for that URL (#{params[:openid_url]})."
    render :action => "new"
  rescue OpenID::OpenIDError
    flash.now[:error] = "An unknown OpenID related error occurred."
    render :action => "new"
  end

  def complete
    response = openid_consumer.complete(request.query_parameters, request.url)
    if response.status == :success
      sreg = ::OpenID::SReg::Response.from_success_response(response).inspect
      p sreg["nickname"]
      p sreg["fullname"]
      p sreg["email"]
      session[:open_id] = response.identity_url
      redirect_to root_path
    else
      flash[:error] = "An unknown error occurred when handling the OpenID response."
      redirect_to login_path
    end
  end

  def destroy
    session.delete(:open_id)
    redirect_to root_path
  end

  private

  def openid_consumer    
    # OpenID::Store::Filesystem.new(Rails.root.join('tmp/openids'))
    # OpenID::Store::Memory.new
    @openid_consumer ||= OpenID::Consumer.new(openid_session, OpenID::Store::Filesystem.new(Rails.root.join('tmp/openids')))
  end

  def openid_session
    session[:openid_consumer] ||= {}
  end
end

routes.rb

YourApp::Application.routes.draw do |map|
  scope :controller => "login"do
    match "login" => :new, :via => :get
    match "login" => :create, :via => :post
    match "login/complete" => :complete
    match "logout" => :destroy
  end

  root :to => "projects#index"
end