- From: Steve Harris <steve.harris@garlik.com>
- Date: Fri, 14 Aug 2009 16:57:54 +0100
- To: Lee Feigenbaum <lee@thefigtrees.net>
- Cc: "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
On 14 Aug 2009, at 14:34, Lee Feigenbaum wrote: > Steve Harris wrote: > >>> Option 8 - New protocol operation (?serviceDescription) >>> >>> A request to a URI such as /endpoint/sparql?serviceDescription >>> returns the service description. Argument for: Simple extension of >>> SPARQL protocol that maps nicely to non-HTTP instantiations of the >>> protocol. Easy to implement and invoke. A well-known pattern from >>> Web Services stacks. Argument against: ?? Not sure, other than >>> Steve is ok with it but not thrilled. :-) >> There is an annoyance with it, which only just occurred to me. >> There's no really easy way to reference the actual endpoint with a >> relative URI, which is sadly necessary in many situations. >> You can use </endpoint/sparql>, in the example above, but that >> won't work in the general case if the endpoint is being reverse >> proxied. > > Steve, > > I'm feeling a bit dense today, but don't totally understand what > you're saying here. Mind giving an example? Sorry, the message was a bit terse. Imagine you have a SPARQL server running on http://localhost:8080/sparql/ , internally to a server, firewalled, and you want to reflect that externally as https://machine.example.com/myapp/sparql/ using a reverse proxy (this might sound a bit odd, but I know of at least three companies that are doing exactly this). If the service description if fetched from the exact endpoint URI, and the description looks like: <> a sparql:Endpoint ; sparql:has sparql:featureA ; ... Then it will all work fine, from both the native endpoint and via the proxy. However, if the description of http://localhost:8080/sparql/ lives at http://localhost:8080/sparql/?serviceDescription , then you can't use <>, so you have to write something like: </sparql> a sparql:Endpoint ; sparql:has sparql:featureA ; ... And that will give you an incorrect and unhelpful answer if you request it as https://machine.example.com/myapp/sparql/?serviceDescription - Steve -- Steve Harris Garlik Limited, 2 Sheen Road, Richmond, TW9 1AE, UK +44(0)20 8973 2465 http://www.garlik.com/ Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
Received on Friday, 14 August 2009 15:58:33 UTC