RDF 1 1 Concepts and Abstract Syntax Yanan

RDF 1. 1 Concepts and Abstract Syntax Yanan Zhang 2021/3/6 1

contents � RDF current status � Introduction to RDF 1. 1 Concepts and Abstract Syntax � Changes from RDF 2004 to this version 2021/3/6 2

RDF current status � � � RDF Model and Syntax (1999 Recommendation) and RDF Schema (2000 Candidate Recommendation). ……. W 3 C Recommendation 10 February 2004 ◦ ◦ ◦ � Group notes ◦ ◦ ◦ � RDF Concepts and Abstract Syntax RDF Semantics RDF Primer RDF Vocabulary Description Language 1. 0 : RDF Schema RDF/XML Syntax Specification RDF Test Cases Microdata to RDF Interfaces ……. RDF 1. 1 Concepts and Abstract Syntax(2012 -06 -05) 2021/3/6 3

The Resource Description Framework (RDF) • is a framework for representing information in the Web. • has an abstract syntax that reflects a simple graph-based data model, and formal semantics. • that allows data to be shared and reused across application, enterprise, and community boundaries. 2021/3/6 4

Introduction to RDF 1. 1 Concepts and Abstract Syntax � Graph-based Data Model RDF/XML 2021/3/6 5

IRI (Internationalized Resource Identifier) � IRIs are a generalization of URIs. ◦ IRI: Universal Character Set (Unicode/ISO 10646). ◦ URI: a subset of the ASCII character set � As globally unique identifiers that describes resources(its referent), and as starting points for RESTful interaction with these resources. http: //www. w 3. org/2000/10/swap/pim/contact#Person 2021/3/6 6

RDF Vocabularies and Namespace IRIs � a collection of IRIs with clearly established referents intended for use in RDF graphs. ◦ eg. classes such as exterms: Tent, ◦ properties such as exterms: model, exterms: weight. In. Kg, and exterms: packed. Size � RDF Vocabulary Description Language : RDF Schema ◦ rdfs: Class rdfs: sub. Class. Of rdf: type rdf: Property rdfs: domain, rdfs: range, and rdfs: sub. Property. Of ◦ http: //www. w 3. org/TR/2004/REC-rdf-schema-20040210/ � The IRIs in an RDF vocabulary often share a common substring known as a namespace IRI. 2021/3/6 7

blank node � something with the given relationships exists, without explicitly naming it. � Replacing blank nodes with IRIs, use a well-known IRI with the registered name genid. ◦ http: //example. com/. well-known/genid/d 26 a 2 d 0 e 98334696 f 4 ad 70 a 677 abc 1 f 6 2021/3/6 8

literal � A literal in an RDF graph consists of: ◦ a lexical form being a Unicode string, ◦ a datatype IRI being an IRI that establishes the literal value. ◦ e. g. "27"^^http: //www. w 3. org/2001/XML Schema#integer "1999 -08 -16"^^http: //www. w 3. org/2001/XML Schema#date � A language-tagged string is any literal whose datatype IRI is equal to http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#lang. String. � simple literals, datatype IRI http: //www. w 3. org/2001/XMLSchema#string. � In earlier versions of RDF ◦ Plain literals ◦ Typed literals 2021/3/6 9

Datatypes � lexical space lexical-to-value mapping � The XML Schema Built-in Datatypes � xsd: boolean ◦ RDF-compatible XSD types, http: //www. w 3. org/2001/XMLSchema#xxx, where xxx is the name of a datatype. ◦ Added xsd: duration , xsd: day. Time. Duration, xsd: year. Month. Duration and xsd: date. Time. Stamp � The rdf: XMLLiteral Datatype ◦ http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#XMLLiteral � The rdf: HTML Datatype ◦ http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#HTML. 2021/3/6 10

Changes from RDF 2004 to this version � � � � � Introduced a datatype for language-tagged strings, and one for HTML fragments Modified the lexical space and value space of the rdf: XMLLiteral datatype Updated the list of RDF-compatible XSD types to reflect XML Schema 1. 1 a section on skolemization of blank nodes Add a note that explains that #x 0 -#x 1 F are no longer allowed in simple literals Changed “RDF URI Reference” to “IRI” Renamed “graph equivalence” to “graph isomorphism” many updated references to other specifications Added a Conformance section 2021/3/6 11

Thanks! 2021/3/6 12