Chapter 4

Semantic Web Application StructureBy NK

Keyword

• RDF store• RDF query engine• SPARQL• SPARQL endpoint• Application interface• Scraper• Converter• RDFa & GRDDL

Context

• RDF Parser / Serializer• RDF Store

RDF Parser / Serializer ( 1 )

• RDF Parser– can read RDF Application’s data source that

has .rdf extension.– has a data source as an Input data.– translate data source into triple

RDF Parser / Serializer ( 2 )

• Serializer– It is a Reverse Operation– Using a RDF parser and Serializer to possible the

'Round-trip' of the triple.– What mean is ‘Round-trip’?

RDF Parser / Serializer ( 3 )

• Example for Serializer Format– N-Triples

RDF Store ( 1 )

• Store RDF Data• Using each parser and serializer for ‘Populate’

and ‘Publish’• In contrast to a relational data store, includes

as a fundamental capability the ability to ‘merge’ two data sets together– Because of Flexible nature of the RDF data model.

RDF Store ( 2 )

• RDF Data Standards and Interoperability of RDF Stores– Relational data store is a difficult process to transfer a

whole database from one system to another.– But RDF data model is a shared by all of these products– All of them can import and export their data sets in the

RDF/XML format.– This feature, early and aggressive standardization

process, makes it much easier to begin with one RDF store, secure in the knowledge that the system can be migrated to another as the need arises.

RDF Store ( 3 )

• RDF Query Engines and SPARQL– Accessed using a query language.– Cover the highlights of SPARQL query language in

this section.

RDF Store ( 4 )

• RDF Query Engines and SPARQLN3 Graph

RDF Store ( 5 )

• RDF Query Engines and SPARQL– The basic building block of a SPARQL query is the

triple pattern.– Variables are indicated as symbols preceded by

the special ‘?’ character.– Example• ?w lit:wrote lit:KingLear .

lit:Shakespeare ?r lit:KingLear.lit:Shakespeare lit:wrote ?p.

RDF Store ( 6 )

• RDF Query Engines and SPARQL– Who wrote King Lear?– What relationship did Shakespeare have to King Lear?– What did Shakespeare write?

RDF Store ( 7 )

• RDF Query Engines and SPARQL– Interesting query is one in which the query

specifies a graph pattern.– A graph pattern is specified as a set of triple

patterns, with the stipulation that any variable that appears in two or more triple patterns must match the same resource in the graph.

– In SPARQL syntax, graph patterns are given as a list of triple patterns enclosed within braces ({ and }).

RDF Store ( 8 )

• RDF Query Engines and SPARQL– ?person lit:wrote lit:KingLear .}

{?person bio:livedIn ?place.?place geo:isIn geo:England.?person lit:wrote lit:KingLear . }

RDF Store ( 8 )

• RDF Query Engines and SPARQL

– It has no knowledge that marriage is a symmetric union and so Shakespeare must have married Anne Hathaway.

– Solution OWL (Will Learn Chapter 7)

Summary

• What are RDF Parser and Serializer• How operation RDF Store• How access RDF Store using RDF Query engine• SPARQL• SPARQL endpoint