@Override
 @Secured({"ROLE_USER"})
 @Transactional(readOnly = true)
 public boolean exist(long id) {
   LOGGER.debug("Exist computer with id : {}", id);
   return computerDAO.exists(id);
 }
 @Override
 @Secured({"ROLE_ADMIN"})
 public void create(Computer c) {
   LOGGER.debug("Create computer : {}", c);
   if (computerDAO.exists(c.getId())) {
     throw new IllegalArgumentException("The computer already exists");
   }
   computerDAO.save(c);
 }
 @Override
 @Secured({"ROLE_ADMIN"})
 public void update(Computer c) {
   LOGGER.debug("Update computer : {}", c);
   if (c == null) {
     throw new IllegalArgumentException("You must specify a computer");
   }
   // Check the Computer already exists
   if (!computerDAO.exists(c.getId())) {
     throw new IllegalArgumentException("Computer with id " + c.getId() + " not found !");
   }
   computerDAO.save(c);
 }