rack_app.rb

require 'rack'
require 'json'

class ApiApp
  def initialize
    @views = {}
  end

  def call(env)
    req = Rack::Request.new(env)
    @views[req.path] ||= 0
    @views[req.path] += 1
    response
  end

  def response
    [
      200, 
      {'Content-type' => 'application/json'},
      [{ views: @views }.to_json]
    ]
  end
end

Rack::Handler::WEBrick.run(ApiApp.new)