restws.api.php

Oh, yes this is very much missing.

+ catch (Exception $e) {}
+ throw new RestWSException('Creation error', 406);

Wrong parentheses.. ;)

>+ */
+ public function delete($id) {
+ try {
+ rules_invoke_component('mymodule_book_service_delete', $id);
+ return;

Just going with mymodule_book_delete() probably would make more sense for people here?