- From: Rob Warren <warren@muninn-project.org>
- Date: Fri, 19 Apr 2013 10:25:16 -0300
- To: Jerven Bolleman <jerven.bolleman@isb-sib.ch>, public-lod@w3.org
> Hi Rob, > > There is a fundamental problem with HTTP status codes. > Lets say a user submits a complex but small sparql request. > > My server sees the syntax is good and starts to reply in good faith. > This means the server starts the http response and sends an 200 OK > Some results are being send.... > However, during the evaluation the server gets an exception. > What to do? I can't change the status code anymore... Is this really so? Failures in large transfers are common and there are a few ways to detect it from the client's end (wrong format, wrong Content-Length and dropped connection). There are SPARQL server implementation specifics here, but it's possible to have a good statistical estimate of whether the query runtime or expected transfer amount will exceed the limits before firing the query. Since the query planner has to do this processing before returning triples, you can decide to fire the query or just refuse the request with an error header based on your limits. If your estimation is wrong and you have to kill the query at runtime, you can re-tune the query planner / optimizer statistics to be more conservative at the next request. rhw
Received on Friday, 19 April 2013 13:25:44 UTC