Re: [Bigdata-developers] Handling of URL encoded strings in SPARQL queries submitted via HTTP

[Steve B. <ste...@va...>]

Followup: I performed this query:

PREFIX wdt: <http://www.wikidata.org/prop/direct/>
SELECT DISTINCT ?country WHERE {
     ?country wdt:P1448 "中华人民共和国"@zh-hans.
}

on the Wikidata Blazegraph endpoint using this URI:

https://query.wikidata.org/sparql?query=PREFIX%20wdt%3A%20%3Chttp%3A%2F%2Fwww.wikidata.org%2Fprop%2Fdirect%2F%3E%0ASELECT%20DISTINCT%20%3Fcountry%20WHERE%20%7B%0A%20%20%20%20%3Fcountry%20wdt%3AP1448%20%22%E4%B8%AD%E5%8D%8E%E4%BA%BA%E6%B0%91%E5%85%B1%E5%92%8C%E5%9B%BD%22%40zh-hans.%0A%7D

and I got a result.  So I guess my problem is not a Blazegraph one, per se.

Steve

On 6/29/17 12:33 PM, Steve Baskauf wrote:
> We have set up a Blazegraph instance at https://sparql.vanderbilt.edu 
> and have loaded it with data.  Those data include multilingual 
> translations of a controlled vocabulary.  The problem I'm having 
> occurs when I send via HTTP to the endpoint a query that contains URL 
> encoded literals that represent non-ASCII UTF-8 characters from other 
> languages.  Here is a query that contains a literal with the character 
> "ú" (URL encoded as %C3%BA):
>
> SELECT DISTINCT ?term where {
> ?term <http://www.w3.org/2000/01/rdf-schema#isDefinedBy> 
> <http://rs.tdwg.org/cv/status/>.
> ?term <http://www.w3.org/2004/02/skos/core#hiddenLabel> 'Común'.
> }
>
> If I paste the query into the Blazegraph SPARQL endpoint GUI box at 
> https://sparql.vanderbilt.edu, I get a single result: the URI 
> <http://rs.tdwg.org/cv/status/extant> as I should.  However, if I URL 
> encode the query and sent it to the same Blazegraph endpoint via HTTP 
> GET as:
>
> https://sparql.vanderbilt.edu/sparql?query=SELECT%20DISTINCT%20%3Fterm%20where%20%7B%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23isDefinedBy%3E%20%3Chttp%3A%2F%2Frs.tdwg.org%2Fcv%2Fstatus%2F%3E.%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2004%2F02%2Fskos%2Fcore%23hiddenLabel%3E%20%27Com%C3%BAn%27.%0A%7D 
>
>
> there are no results.  I'm confident that the URL encoding is correct 
> because if the same query is sent via HTTP GET to our old 
> Callimachus-based endpoint, it returns the correct URI:
>
> http://rdf.library.vanderbilt.edu/sparql?query=SELECT%20DISTINCT%20%3Fterm%20where%20%7B%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23isDefinedBy%3E%20%3Chttp%3A%2F%2Frs.tdwg.org%2Fcv%2Fstatus%2F%3E.%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2004%2F02%2Fskos%2Fcore%23hiddenLabel%3E%20%27Com%C3%BAn%27.%0A%7D 
>
>
> The problem appears to be with the endpoint's handling of the encoded 
> literal characters.  If I change the literal to one that does not 
> contain non-ASCII characters, such as "common" (a hidden label synonym 
> of "Común"), so that the query is:
>
> SELECT DISTINCT ?term where {
> ?term <http://www.w3.org/2000/01/rdf-schema#isDefinedBy> 
> <http://rs.tdwg.org/cv/status/>.
> ?term <http://www.w3.org/2004/02/skos/core#hiddenLabel> 'common'.
> }
>
> the URL encoded HTTP GET:
>
> https://sparql.vanderbilt.edu/sparql?query=SELECT%20DISTINCT%20%3Fterm%20where%20%7B%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23isDefinedBy%3E%20%3Chttp%3A%2F%2Frs.tdwg.org%2Fcv%2Fstatus%2F%3E.%0A%3Fterm%20%3Chttp%3A%2F%2Fwww.w3.org%2F2004%2F02%2Fskos%2Fcore%23hiddenLabel%3E%20%27common%27.%0A%7D 
>
>
> produces the correct result.
>
> I am at a loss as to where to go with this as far as trouble-shooting 
> is concerned.  It's possible that there is some incorrect server 
> configuration setting that I don't know about.  I suppose it's also 
> possible that it's a bug.  This is a rather serious problem for us 
> because we have significant multilingual data in the triplestore and 
> users need to be able to search against it.
>
> Steve Baskauf
>

-- 
Steven J. Baskauf, Ph.D., Senior Lecturer
Vanderbilt University Dept. of Biological Sciences

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