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Internet Technologies

Internet Technologies. Making Queries on RDF. Two Approaches. SPARQL - Simple Protocol And RDF Query Language - Looks like SQL - Used by Dbpedia MQL - Metaweb Query Language - Based on JSON - Used by Freebase. Both freebase and Dbpedia

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Internet Technologies

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  1. Internet Technologies Making Queries on RDF Master of Information System Management

  2. Two Approaches • SPARQL - Simple Protocol And RDF Query Language - Looks like SQL - Used by Dbpedia • MQL - Metaweb Query Language - Based on JSON - Used by Freebase Both freebase and Dbpedia make their statements available in RDF. Master of Information System Management

  3. Today’s Lecture • A brief look at SPARQL • A brief look at MQL Master of Information System Management

  4. SPARQL • SPARQL Simple Protocol and RDF Query Language • W3C Recommendation January 2008 • Queries written using Turtle - Terse RDF Triple Language • Download Jena and ARQ Query Engine • For Ruby, see ActiveRDF Master of Information System Management

  5. SPARQL • Three specifications: (1) A query language (2) A query results XML format (3) A WSDL 2.0 Data Access Protocol using HTTP and SOAP • SPARQL is read only and cannot modify the RDF data Master of Information System Management

  6. Input <?xml version="1.0" encoding="UTF-8"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:rss="http://purl.org/rss/1.0/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:html="http://www.w3.org/1999/xhtml"> <foaf:Agent rdf:nodeID="id2246040"> <foaf:name>John Barstow</foaf:name> <rdf:type rdf:resource="http://xmlns.com/foaf/0.1/Person"/> <foaf:weblog> <foaf:Document rdf:about="http://www.nzlinux.org.nz/blogs/"> <dc:title>Visions of Aestia by John Barstow</dc:title> <rdfs:seeAlso> <rss:channel rdf:about="http://www.nzlinux.org.nz/blogs/wp-rdf.php?cat=9"> <foaf:maker rdf:nodeID="id2246040"/> <foaf:topic rdf:resource="http://www.w3.org/2001/sw/"/> <foaf:topic rdf:resource="http://www.w3.org/RDF/"/> </rss:channel> </rdfs:seeAlso> </foaf:Document> </foaf:weblog> <foaf:interest rdf:resource="http://www.w3.org/2001/sw/"/> <foaf:interest rdf:resource="http://www.w3.org/RDF/"/> </foaf:Agent> </rdf:RDF> This is shortblogger.xml The file bloggers.xml has many bloggers. Master of Information System Management

  7. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?url FROM <shortblogger.xml> WHERE { ?contributor foaf:name "John Barstow" . ?contributor foaf:weblog ?url . } Stored in a file called ex1.rq Master of Information System Management

  8. Output sparql --query ex1.rq ------------------------ | url | ========================= | <http://www.nzlinux.org.nz/blogs/> | -------------------------------------------- Master of Information System Management

  9. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT ?url FROM <shortblogger.xml> WHERE { ?contributor rdf:type foaf:Person . ?contributor foaf:weblog ?url . } Output sparql --query ex2.rq ------------------------- | url | =============== | <http://www.nzlinux.org.nz/blogs/> | ------------------------- Master of Information System Management

  10. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT ?x ?n FROM <bloggers.xml> WHERE { ?contributor rdf:type foaf:Person . ?contributor foaf:weblog ?x . ?contributor foaf:name ?n } All three conditions must be satisfied to match the query. Master of Information System Management

  11. Output sparql --query ex4.rq -------------------------------------------------------------------------------------- | x | n | ================================================ | <http://www.picklematrix.net/semergence/> | "Seth Ladd" | | <http://www.wasab.dk/morten/blog/> | "Morten Frederiksen" | | <http://www.lassila.org/blog/> | "Ora Lassila" | | <http://people.w3.org/~dom/> | "Hazaël-Massieux" | | <http://xmlarmyknife.org/blog/> | "Leigh Dodds" | | <http://blogs.sun.com/bblfish/> | "Henry Story" | | <http://jeenbroekstra.blogspot.com/> | "Jeen Broekstra" | | <http://people.w3.org/~djweitzner/blog/?cat=8> | "Danny Weitzner" | | <http://danbri.org/words/> | "Dan Brickley" | Master of Information System Management

  12. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT DISTINCT ?n FROM <bloggers.xml> WHERE { ?contributor foaf:name ?n } Output ----------------------------------------- | n | ================= | ”Mike McCarthy" | | "Pasquale Popolizio" | | "Dean Allemang" | : : Master of Information System Management

  13. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT DISTINCT ?n FROM <bloggers.xml> WHERE { ?contributor foaf:name ?n } ORDER BY ?n ---------------------- | n | ============= | "Alexandre Passant" | | "Alistair Miles" | | "Andrew Matthews" | | "Benjamin Nowack" : : Master of Information System Management

  14. Semi-Structured Data • Definition: If two nodes of the same type are allowed to hold different sets of properties the data is called semi-structured. • SPARQL uses the OPTIONAL keyword to process semi-structured data. Master of Information System Management

  15. Processing PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT DISTINCT ?n ?interest FROM <bloggers.xml> WHERE { ?contributor foaf:name ?n . OPTIONAL { ?contributor foaf:interest ?interest } } ORDER BY ?n "Tetherless World Constellation group RPI" <http://www.w3.org/2001/sw/> "Tetherless World Constellation group RPI" <http://www.w3.org/RDF/> "Tim Berners-Lee" "Uldis Bojars" <http://www.w3.org/2001/sw/> "Uldis Bojars" <http://www.w3.org/RDF/> Master of Information System Management

  16. Generating XML PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT ?n FROM <shortblogger.xml> WHERE { ?contributor foaf:name ?n . } Master of Information System Management

  17. From The Command Line sparql --query ex8.rq --results rs/xml <?xml version="1.0"?> <sparql xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:xs="http://www.w3.org/2001/XMLSchema#" xmlns="http://www.w3.org/2005/sparql-results#" > <head> <variable name="n"/> </head> <results> <result> <binding name="n"> <literal>John Barstow</literal> </binding> </result> </results> </sparql> Master of Information System Management

  18. MQL • Metaweb Query Language • Make queries against the freebase data store. • The input and outputs are JSON strings. Master of Information System Management

  19. Using MQL In A URL Example from the MQL documentation. Enter the following in your browser: https://api.freebase.com/api/service/mqlread?query= {“query”:{“type”:”/music/artist”,”name”:”The Police”,”album”:[]}} This is a query to freebase represented in JSON. Master of Information System Management

  20. Output { "code": "/api/status/ok", "result": { "album": [ "Outlandos d'Amour", "Reggatta de Blanc", "Zenyatt\u00e0 Mondatta” "The Police Live!" ], "name": "The Police", "type": "/music/artist" }, "status": "200 OK", "transaction_id”:"cache;cache03.p01.sjc1:8101;2011-10-13T15” } Many more albums in the real query result. Master of Information System Management

  21. Another look at the query. { "query": { "type":"/music/artist", "name":"The Police", "album":[] } } Master of Information System Management

  22. Use The Query Editor http://www.freebase.comqueryeditor Master of Information System Management

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