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Re: [dotNetRDF-Support] "underlying connection was closed" errors when talking to Stardog
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From: Rob V. <rv...@do...> - 2014-11-25 10:43:45
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Reading the Stardog support thread it sounds like we can just turn on Keep-Alive and keep using HTTP 1.1 Please go ahead and make the changes Rob From: Ron Michael Zettlemoyer <ro...@ze...> Reply-To: dotNetRDF User Help and Support <dot...@li...> Date: Thursday, 13 November 2014 16:22 To: dotNetRDF User Help and Support <dot...@li...> Subject: Re: [dotNetRDF-Support] "underlying connection was closed" errors when talking to Stardog > Thanks Rob. I have a message up on the Stardog forum to see if they have any > thoughts. I'll see what they say... > > > On Wed, Nov 12, 2014 at 4:32 AM, Rob Vesse <rv...@do...> wrote: >> Ron >> >> 1 - No idea why it would have changed, check with the Stardog folks to see if >> there have been any changes in their HTTP server implementation recently >> >> Particularly the fact that it tends to happen only with POSTs may imply some >> sort of issue on the server side. Have you tried reproducing this using the >> same queries that fail via CURL or another SPARQL API? >> >> 2 - Well it is a proxy so it is doing something with the requests and adds an >> additional connection hop to the pathway. Fiddler may be handling >> connections differently to .Net >> >> 3 - I'd prefer to see what the Stardog folks think before making these >> changes especially if there is a possibility of a bug in their server being >> the culprit. >> >> HTTP 1.0 is rather old now and there is a recent it is so infrequently used, >> one particular thing to be aware of is that it may not support more secure >> authentication mechanisms so you may be sending your Stardog credentials in >> clear text (or at best lightly encoded text) if you use HTTP 1.0 >> >> Rob >> >> From: Ron Michael Zettlemoyer <ro...@ze...> >> Reply-To: dotNetRDF User Help and Support >> <dot...@li...> >> Date: Wednesday, 12 November 2014 02:59 >> To: dotNetRDF User Help and Support >> <dot...@li...> >> Subject: [dotNetRDF-Support] "underlying connection was closed" errors when >> talking to Stardog >> >>> I've just recently started getting these weird "The underlying connection >>> was closed: A connection that was expected to be kept alive was closed by >>> the server" errors when talking to a Stardog database. Here are the >>> particulars: >>> * Mostly happens when the Stardog database is on a remote server - in this >>> case when I'm at home and querying a Windows 2012 server hosted at Azure. >>> When talking to the database locally from the same box (at Azure) it rarely >>> exhibits this behavior. >>> * Same thing happens if I query Stardog on a Linux server at Azure >>> * If I use a proxy between dotNetRDF and Stardog - like Fiddler - to examine >>> what's going on, it always works! But stop using the proxy and it fails. >>> Which makes it hard to diagnose. >>> * It only seems to fail when the SPARQL query is long and a POST is >>> necessary. GETs for query queries don't seem to fail. >>> After playing around and Googling for a while, I found this post >>> (http://stackoverflow.com/questions/13188058/httpwebrequest-the-underlying-c >>> onnection-was-closed) that suggested setting these options in the >>> WebRequest: >>> >>> request.KeepAlive = false; >>> request.ProtocolVersion = HttpVersion.Version10; >>> >>> I added this to the CreateRequest function in BaseStardogConnector and it >>> seems to have fixed the problem! >>> >>> So three questions: >>> >>> 1- Anyone have any ideas why this problem would seem to start for no reason, >>> after it'd been working fine for months? >>> >>> 2- Any idea why proxying through Fiddler would hide the problem? Shouldn't >>> it be passing the request straight through? >>> >>> 3- Is there any reason we shouldn't merge these changes into the codebase? >>> >>> >>> - Ron >>> >>> ---------------------------------------------------------------------------- >>> -- Comprehensive Server Monitoring with Site24x7. Monitor 10 servers for >>> $9/Month. Get alerted through email, SMS, voice calls or mobile push >>> notifications. Take corrective actions from your mobile device. >>> http://pubads.g.doubleclick.net/gampad/clk?id=154624111&iu=/4140/ostg.clktrk >>> _______________________________________________ dotNetRDF-Support mailing >>> list >>> dot...@li...https://lists.sourceforge.net/lists/l >>> istinfo/dotnetrdf-support >> >> ----------------------------------------------------------------------------->> - >> Comprehensive Server Monitoring with Site24x7. >> Monitor 10 servers for $9/Month. >> Get alerted through email, SMS, voice calls or mobile push notifications. >> Take corrective actions from your mobile device. >> http://pubads.g.doubleclick.net/gampad/clk?id=154624111&iu=/4140/ostg.clktrk >> _______________________________________________ >> dotNetRDF-Support mailing list >> dot...@li... >> https://lists.sourceforge.net/lists/listinfo/dotnetrdf-support >> > > ------------------------------------------------------------------------------ > Comprehensive Server Monitoring with Site24x7. Monitor 10 servers for > $9/Month. Get alerted through email, SMS, voice calls or mobile push > notifications. Take corrective actions from your mobile device. > http://pubads.g.doubleclick.net/gampad/clk?id=154624111&iu=/4140/ostg.clktrk__ > _____________________________________________ dotNetRDF-Support mailing list > dot...@li... > https://lists.sourceforge.net/lists/listinfo/dotnetrdf-support |
