Sparql endpoint toegang

Datasets
#1

Beste L.s.,

Is het mogelijk om de PDOK LOD platform te gebruiken in een federated sparql query zoals bijv:

SELECT *

WHERE {
  SERVICE <https://data.pdok.nl/ldt/sparql> { 
    ?a ?b ?c
  }
}
limit 10

Is dit het juiste adres voor de service?

alvast bedankt.

Hans

#2

Hoi Hans,

Hier wordt nog hard aan gewerkt! De url zou nog wel omsloten moeten worden met <>, maar het is nog niet ondersteunt. Je vraag staat een onze issue lijst als reminder, zou je willen geĂŻnformeerd willen worden als deze functionaliteit wel beschikbaar is? If yes dan plak ik je email (als je die wil geven) er ook even aan vast, dan geven we een gil als het zover is !

Namens het grid team

Gr Werner

#3

Hoi Hans,

De service https://data.pdok.nl/sparql (dus zonder /ldt) ondersteunt nu federated queries.

Groet, Dimitri

#4

@dvh
Dear Dimitri,

I am trying to access https://data.pdok.nl/sparql through oracle spatial and graph but to no avail. I am keep getting errors:

ORA-20000: Service request cannot be completed.
ORA-29273: HTTP request failed
Nevertheless, with dbpedia sparql endpoint, it works.

Regards,
Evangelos

#5

Dear @ETheo,

Based on the information that you give the team cannot help you. Could you provide more specific information on the request that you make? Preferably the exact request that is made and the exact error that our sparql endpoint provides.

One thing that we can imagine is that you are running into SSL-certificates issues (as we use PKI-overheid certificates who are not always trusted by all systems). More information on SSL-issues are provided in the following topic: https://forum.pdok.nl/t/how-to-work-with-the-overheid-certificaat-in-java-applications/253

1 like
#6

Dear @jasperroes ,
I am trying the query bellow

SELECT *
FROM TABLE(SEM_MATCH(
'SELECT *
WHERE {
SERVICE <brk.basisregistraties.overheid.nl/sparql> {

SELECT ?s ?p ?o
WHERE { ?s ?p ?o }
LIMIT 10

}
}’
,sem_models(‘geometries’)
,null,null,null,null));

and I get, ORA-20000: Service request cannot be completed.
ORA-29273: HTTP request failed
ORA-06512: at “SYS.UTL_HTTP”, line 380
ORA-06512: at “SYS.UTL_HTTP”, line 1127
ORA-06512: at “MDSYS.SPARQL_SERVICE_IMPL_T”, line 351
ORA-06512: at “MDSYS.SPARQL_SERVICE_IMPL_T”, line 446
ORA-06512: at line 1
20000. 00000 - “%s”
*Cause: The stored procedure ‘raise_application_error’
was called which causes this error to be generated.
*Action: Correct the problem as described in the error message or contact
the application administrator or DBA for more information.

I think that the SSL certificates are the problem, nevertheless, when I try the solution
in the thread you provided I run into “100 Problems” error message.

content=“escline/InstallCert” />

                                                                         ^

InstallCert.java:85: error: expected

 ^

InstallCert.java:85: error: illegal start of expression

             ^

InstallCert.java:85: error: > expected

                    ^

InstallCert.java:85: error: ‘;’ expected

                                                                           ^

InstallCert.java:85: error: expected

   ^

InstallCert.java:85: error: illegal start of expression

                           ^

InstallCert.java:85: error: > expected

                                  ^

InstallCert.java:85: error: ‘;’ expected

                                ^

InstallCert.java:85: error: expected

                                        ^

InstallCert.java:85: error: illegal start of expression

                                                  ^

InstallCert.java:88: error: > expected

^
InstallCert.java:88: error: ‘;’ expected

^
InstallCert.java:88: error: expected

^
InstallCert.java:88: error: ‘;’ expected

                ^

InstallCert.java:88: error: expected

                     ^

InstallCert.java:88: error: expected

                          ^

InstallCert.java:88: error: illegal start of type

                                    ^

InstallCert.java:88: error: ‘;’ expected

                                     ^

InstallCert.java:91: error: ‘;’ expected

^ InstallCert.java:91: error: expected ^ InstallCert.java:93: error: > expected ^ InstallCert.java:93: error: ';' expected ^ InstallCert.java:93: error: expected ^ InstallCert.java:95: error: > expected ^ InstallCert.java:95: error: ';' expected ^ InstallCert.java:95: error: expected ^ InstallCert.java:95: error: ';' expected ^

InstallCert.java:95: error: expected

 ^

InstallCert.java:96: error: > expected

^ InstallCert.java:96: error: ';' expected ^ InstallCert.java:96: error: expected ^ InstallCert.java:96: error: ';' expected ^ InstallCert.java:96: error: expected ^ InstallCert.java:96: error: illegal start of type ^ InstallCert.java:98: error: > expected ^ InstallCert.java:98: error: ';' expected ^ 100 errors

C:\Program Files\Java\jdk1.8.0_121\jre\lib\security>

#7

I am not an expert in Oracle and/or SSL certificates so I am afraid that it will be difficult for me to help you. I would however suggest you use https://data.pdok.nl/sparql instead of the current url you are using (as that one is redirected) and then ask your Oracle DBA or application manager whether they can help you with the specific Oracle errors that you see.

#8

Thank you very much for your suggestion. I already contacted someone on Oracle too and I am working to bridge the gap from both sides.