re: status code. This is an interesting problem. The http spec does not have a good answer for this right now as you point out below. Internally (we don't use fuseki), our app server returns 503 when a query times out. It is not perfect, but it indicates the temporary nature of the problem, i.e. if you add resources to the machine or change the timeout value, you may get 200 again. Ideally, there is a 4xx class answer since a timeout is not really a server error (unless you consider a lack of CPU/memory a server problem :-) ). I looked at [5] below and 403 does not seem entirely wrong but we didn't choose it (we use 403 for a number of other things and it would require our clients to further disambiguate the cause for 403), although arguably that can also be said for 503. The main difference though is that 503 suggests that retrying could alleviate the problem and that is technically true because a query (in our product) may timeout because the server is overloaded with requests.
Simon From: Alexander Dutton <[email protected]> To: "[email protected]" <[email protected]> Date: 11/09/2011 10:50 AM Subject: QueryCancelledException not being caught in Fuseki -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi all, I'm playing with the --timeout argument to Fuseki (checked out from trunk a couple of days ago). When a query times out the client currently receives the following, which doesn't explain much: > Error 500: Server Error This is the result of a QueryCancelledException being caught at line 107 of SPARQL_ServletBase, which has the comment "This should not happen" It'd be good if this were explicitly caught and a more user-friendly error message provided. I don't know what HTTP status code should be provided[1]. The spec does say 500, but that upsets me (and Hugh Glaser)[2]. Shall I create an issue in JIRA and put together a patch? Yours, Alex [1] I've asked[2] the HTTP WG whether they'd consider the inclusion of a "Request Too Onerous" status code in the new status code draft[3]. [2] There's been previous discussion of this on public-lod[5]. [3] http://lists.w3.org/Archives/Public/ietf-http-wg/2011OctDec/0188.html [4] http://tools.ietf.org/html/draft-nottingham-http-new-status-03 [5] http://lists.w3.org/Archives/Public/public-lod/2011Apr/0259.html ff. - -- Alexander Dutton Metamorphoses Project Developer, Claros Oxford University Computing Services, ℡ 01865 (6)13483 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iEYEARECAAYFAk66oKMACgkQS0pRIabRbjAZ1QCfSBhh8aPVwD3FxM9y1Obxi3f1 zN8AnjDu68k++p5mbi6O9AxZoSGRuzb6 =kJIA -----END PGP SIGNATURE-----
