Service object for converting Base64 encoded image to save with Carrier Wave in Ruby apps

ConvertBase64ImageServiceObject

# Needed for Rails 3+
class FilelessIO < StringIO
  attr_accessor :original_filename
end


class ConvertBase64ImageService

  def call(base64_encoded_image, filename)
    split_encoded = split_base64(base64_encoded_image)
    io = FilelessIO.new(split_encoded[:data])
    io.original_filename = filename
    io
  end

  private
  def split_base64(encoded)
    if encoded.match(%r{^data:(.*?);(.*?),(.*)$})
      {
          type: $1,
          encoder: $2,
          data: Base64.decode64($3),
          extension: $1.split('/')[1]
      }
    end
  end
end

where to write this code? how FilelessIO ,ConvertBase64ImageService classes are called