An example API server 

$ curl -D - http://0.0.0.0:3000/product/NU217EXA
HTTP/1.0 404 Not Found
Server: Perl Dancer 1.3099
Content-Length: 29
Content-Type: application/json
X-Powered-By: Perl Dancer 1.3099

{
   "error" : "Not Found"
}