get  '/service/items' => sub {
  content_type 'application/json' ;
  my $items = $dbh->selectall_arrayref(...) ;
  return to_json($items) ;
} ;

post '/service/items/:item_id' => sub {
  content_type 'application/json' ;
  $dbh->do(...) ;
  return to_json({updated => 1}) ;
} ;

put  '/service/items' => sub {
  content_type 'application/json' ;
  $dbh->do(...) ;
  return to_json({added => 1}) ;
} ;

del  '/service/items/:item_id' => sub {
  content_type 'application/json' ;
  $dbh->do(...) ;
  return to_json({deleted => 1}) ;
} ;