anchor.diff:              {ok, Req1} = cowboy_req:reply(500, [], stringify(Reason), Req0),
               {stop, Req1, State};
           ok ->
  -            {true, Req0, State}
  +            Req1 = set_cross_domain(Req0),
  +            {true, Req1, State}
       end.
   
   content_types_accepted(Req, State) ->
  
positive.code:     end,
      case dbyr_identifier:publish(Identifier, Metadata) of
          ok ->
              {{true, dbyr_identifier:to_resource(Identifier)},
                  cowboy_req:set_resp_body(<<"true">>, Req1), State};
          {error, Reason} ->
              ?ERROR("publish error: ~p~n", [Reason]),
              {false, Req1, State}
      end.
  
  stringify(Reason) ->
      iolist_to_binary(io_lib:format("~p", [Reason])).
  
negative.code:     {true, Req, State}.
  
  known_methods(Req, State) -> 
      {[<<"OPTIONS">>,<<"GET">>,<<"POST">>,<<"DELETE">>], Req, State}.
  
  allowed_methods(Req, State) ->
      {[<<"OPTIONS">>,<<"GET">>,<<"POST">>,<<"DELETE">>], Req, State}.
  
  content_types_provided(Req, State) ->
      {[{<<"application/json">>, handle_json}], Req, State}.
  
  options(Req0, State) ->
      Req1 = cowboy_req:set_resp_header(<<"Access-Control-Allow-Headers">>,
                                                      <<"content-type">>, Req0),
      {ok, Req1, State}.
  
  resource_exists(Req0, #{identifier := Identifier} = State) ->
      case dbyr_identifier:get_metadata(Identifier) of
  