look at this

route.rb

def process_params(params)
  @identifier = params[:identifier]
  @rooturl = params[:rootUrl]
  if missing_parameters?(params)
    halt 400, "Bad Request! missing required parameters"
  else
    "#{{identifier: @identifier}.to_json}"
  end
end

def missing_parameters?(params)
  identifier = params[:identifier]
  root = params[:rootUrl]
  if identifier == nil || identifier == ""
    true
  elsif root == nil || root == ""
    true
  else
    false
  end
end