Querying the Web of Data with XSPARQL 1.1

Querying the Web of Data with

XSPARQL 1.1

Daniele Dell’Aglio (DEIB, Politecnico di Milano)

Axel Polleres (Vienna University of Economics and Business)

Nuno Lopes (IBM Research Ireland)

Stefan Bischof (SIEMENS Austria)

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What is XSPARQL?

19 October 2014 - ISWC Dev Workshop 2014 Querying the Web of Data with XSPARQL 1.1 2

XSPARQL is a transformation language to conveniently

query XML and RDF side-by-side

It is a syntactic extension of XQuery

A SPARQL-for clause to query RDF data (by using SPARQL

operators)

A CONSTRUCT clause to produce RDF output

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What is XSPARQL?


XSPARQL is a transformation language to conveniently

query XML and RDF side-by-side

It is a syntactic extension of XQuery

A SPARQL-for clause to query RDF data (by using SPARQL

operators)

A CONSTRUCT clause to produce RDF output

Several improvements during the years

Support for querying RDBMS data sources

Support for R2RML

Query optimisations

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Where to go to learn headbanging?

We want to retrieve the list of upcoming concerts of music artists having Nuclear Blast as music label

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ipedia


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We can get

The list of the artists from DBPedia

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ipedia


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We can get


The concerts on Last.fm

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ipedia


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We can get



And put data… together?

Different data sources

Different formats (JSON, RDF)

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ipedia


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We can get



And put data… together?

Different data sources

Different formats (JSON, RDF)

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ture

s fr

om

Wik

ipedia


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How can XSPARQL 1.1 help us?

1. prefix lastfm: <http://xsparql.deri.org/lastfm#>

2. prefix dbprop: http://dbpedia.org/property/

3. prefix dbpedia: <http://dbpedia.org/resource/>

4. for *

5. where {

6. service <http://dbpedia.org/sparql> {

7. $artist a dbowl:Band ;

8. dbprop:label dbpedia:Nuclear_Blast ;

9. dbprop:name $artistName .

10. }

11. }

12. return

13. let $doc := fn:concat("http://ws.../artist=",$artistName)

14. for $event in xsparql:json-doc($doc)//events/event/*

15. construct {

16. [] a lastfm:Event ;

17. lastfm:artist {$artistName} ;

18. lastfm:venue {$event/venue/location/city} ;

19. last:date {$event/startDate}

20. }


http://dbpedia.org/property/



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4. for *

5. where {





10. }

11. }

12. return



15. construct {





20. }

Support of SPARQL 1.1

operators: Assignment/Project Expressions

Aggregate functions: SUM, AVG,...

Federation

Negation

Property paths

Subqueries





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4. for *

5. where {





10. }

11. }

12. return



15. construct {





20. }

Support of SPARQL 1.1

operators: Assignment/Project Expressions

Aggregate functions: SUM, AVG,...

Federation

Negation

Property paths

Subqueries

Processing of JSON files





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How does it work?

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arql

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xsp

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rew

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XSPARQL

query data

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How does it work?

XQuery

query

xsp

arql

eva

luat

or

xsp

arql

rew

rite

r

lexer/parser

rewriter

optimizer

XSPARQL

query data

xsp

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ry


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How does it work?

XQuery

query

XQuery engine

SPARQL engine xsp

arql

eva

luat

or

xsp

arql

rew

rite

r

lexer/parser

rewriter

optimizer

XSPARQL

query

answer

(XML|RDF)

data

xsp

arql-cl

i JA

R L

ibra

ry


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How does it work?

XQuery

query

XQuery engine

SPARQL engine xsp

arql

eva

luat

or

xsp

arql

rew

rite

r

lexer/parser

rewriter

optimizer

XSPARQL

query

answer

(XML|RDF)

data

xsp

arql-cl

i JA

R L

ibra

ry


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How does it work?

…

XSPARQLEvaluator evalutor =

new XSPARQLEvaluator();

Reader query = ...;

Writer out = ...;

evalutor.evaluate(query, out);

…

XQuery

query

XQuery engine

SPARQL engine xsp

arql

eva

luat

or

xsp

arql

rew

rite

r

lexer/parser

rewriter

optimizer

XSPARQL

query

answer

(XML|RDF)

data

xsp

arql-cl

i JA

R L

ibra

ry


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Whats next?


Use of different SPARQL engines

openRDF and Strabon

Support to JSON-LD

No full control flow

XQUERY/XSPARQL don’t allow you to specify politeness (e.g.

crawl delays between doc(.) calls)

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Thank you!

Querying the Web of Data with XSPARQL 1.1

http://xsparql.deri.org

http://sourceforge.net/projects/xsparql

Daniele Dell’Aglio, Axel Polleres, Nuno Lopes

and Stefan Bischof

[email protected]

(Thank you, SWSA and Google, for my Student Travel

grant!)


http://xsparql.deri.org/

http://xsparql.deri.org/



mailto:[email protected]

mailto:[email protected]

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The last slide :)

19 October 2014 - ISWC Dev Workshop 2014 Querying the Web of Data with XSPARQL 1.1

XQuery

query

XQuery engine

SPARQL engine xsp

arql

eva

luat

or

xsp

arql

rew

rite

r

lexer/parser

rewriter

optimizer

XSPARQL

query

answer

(XML|RDF)

data

xsp

arql-cl

i JA

R L

ibra

ry

Pic

ture

s fr

om

Wik

ipedia

8

Technology

Querying the Web of Data with XSPARQL 1.1