doc.: ieee 802.19-01/0169r0 submission joe kwak (interdigital) slide 1 november 2010 slide 1...

Joe Kwak (InterDigital)Slide 1

doc.: IEEE 802.19-01/0169r0

Submission

November 2010

Slide 1

Overview of Resource Description Framework (RFD/XML)

Date: 2010-11-11

Name Affiliations Address Phone email Joe Kwak InterDigital POB 93,

Hawkesbury, ON (630) 739-4159 [email protected]

Authors:


doc.: IEEE 802.19-01/0169r0

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Outline

• Basic concept: descriptive statement triple

• RDF/XML representation

• RDF capablilities: containers, collections, reification

• RDF Schema defines application vocabularies

• 802.21 example: RDF Schema for Information Service

• References


doc.: IEEE 802.19-01/0169r0

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Descriptive Statement TRIPLE: Subject | Predicate

RDF GRAPH what | | value

Truck | color | red

created to describe web resources

http://www.example.org/index.html has a creator whose value is John Smith

<http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> RDF in XML of URIs <http://www.example.org/staffid/85740> .

property attributecharacteristic


doc.: IEEE 802.19-01/0169r0

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RDF/XML Representation

XML qualified names (Qnames) used for RDF shorthand.Common xmlns (xml namespace) prefixes:• prefix rdf:, namespace URI: http://www.w3.org/1999/02/22-rdf-syntax-ns#• prefix rdfs:, namespace URI: http://www.w3.org/2000/01/rdf-schema#• prefix dc:, namespace URI: http://purl.org/dc/elements/1.1/• prefix owl:, namespace URI: http://www.w3.org/2002/07/owl#• prefix xsd:, namespace URI: http://www.w3.org/2001/XMLSchema#• prefix ex:, namespace URI: http://www.example.org/ • prefix exstaff:, namespace URI: http://www.example.org/staffid/

Same statement using XML prefixes: ex:index.html dc:creator exstaff:85740 .


doc.: IEEE 802.19-01/0169r0

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Compound Statements and Blank Nodes


doc.: IEEE 802.19-01/0169r0

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Typed Literals

• Default literal is string of ascii for URIs

• RDF Schema defines many standard datatypes

• Online library is commonly referenced

• DataTypes defined in library at http://www.w3.org/2001/XMLSchema

• "value"^^<DataTypeLibrary # datatypename>


doc.: IEEE 802.19-01/0169r0

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DataTypes defined at http://www.w3.org/2001/XMLSchema


doc.: IEEE 802.19-01/0169r0

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RDF statements in XML

Triple to XML equivalent:


doc.: IEEE 802.19-01/0169r0

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More Complex RDF/XML


doc.: IEEE 802.19-01/0169r0

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RDF Containers• Bag: items in no significant order

• Seq:: items sequenced in a required order– Bag and Seq are semantically identical in XML with <rdf:Bag> - <rdf:Seq>

– Application layer needs to interpret order as significant for sequence only

• Alt: a set of alternative items "one of the below".


doc.: IEEE 802.19-01/0169r0

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Collection uses property concept of "first", "rest" and defines the null node to delimit list.

Collections are closed containers whereas bags and sequences are open.

Collection is a closed linked list


doc.: IEEE 802.19-01/0169r0

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• Reification permits RDF syntax to be applied to RDF statements. Description of the Description.

• RDF triple:

• RDF description of the above RDF statement

• Useful for provenance descriptors: Created By, Creation Date, Version #etc

– These are properties about the code itself– Description NOT about the objects identified and described in the code.

RDF Reification – making the language a thing


doc.: IEEE 802.19-01/0169r0

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RDF permits "Literal" type for XML strings as values

• In this example, the value for the book title is an XML string:"" <span xml:lang="en" The <em><br /><em> Element Considered Harmful.

""

• Note that the string is interpreted as XML and not simply as ascii.


doc.: IEEE 802.19-01/0169r0

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RDF Schemas• A Schema is a particular use of

rdf_class and rdf_property to define particular terms useful for a particular application

• The defined terms are called a VOCABULARY for this RDF application.

• The property relationships among the classes are meaningful.

• The datatype definitions here are an example of a schema.


doc.: IEEE 802.19-01/0169r0

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Customized Schemas are Useful

• Custom schema to describe


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Custom Vehicle Schema in Triples


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Custom Vehicle Schema in RDF/XML

• h


doc.: IEEE 802.19-01/0169r0

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Properties of RDF_Properties• RDF language emphasis and some capabilities differ

from object oriented languages (OOL).

• RDF is a description oriented language (DOL).

• In OOL, objects are type classed and they have properties.

• In DOL, properties have properties and may be abstractly defined.

• Properties have Range and Domain.

has Domain of

OBJECT Value

Property

has Range of


doc.: IEEE 802.19-01/0169r0

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Examples

• Range

• Ranges can also be explicit (0..255)

• Domain

• In a way these RDF statements treat properties like objects


doc.: IEEE 802.19-01/0169r0

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Using EPRI's CIM/XML Schema:


doc.: IEEE 802.19-01/0169r0

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Issues for 19.1• Utility of language for describing message structures

• Ease of use and readability of language for message structures.

• ASN.1 and RDF/XML share most, if not all, features.

• Extensibility is key for ASN.1 vs RDF/XML decision.

• ASN.1 is tightly structured and requires use of "…" placement to permit extensibility.

• RDF allows open ended class and property extensions.There is no "…." construct within RDF.

• IN PRACTICE, we would like to know the shortcomings of both approaches.


doc.: IEEE 802.19-01/0169r0

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Quick look at 802 standards

• 802.11 MIB in ASN.1

• 802.21 Information Service Schema in RDF/XML


doc.: IEEE 802.19-01/0169r0

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References• RDF Primer:

http://www.w3.org/TR/2004/REC-rdf-primer-20040210/#xmlliterals

• RDF Vocabulary Schema: http://www.w3.org/TR/rdf-schema/#ch_domainrange

• RDF/XML Schema: http://www.w3.org/TR/xmlschema-1/ andhttp://www.w3.org/TR/xmlschema-2

• Many many others branch out of the above references.


doc.: IEEE 802.19-01/0169r0

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Discussion

doc.: ieee 802.19-01/0169r0 submission joe kwak (interdigital) slide 1 november 2010 slide 1...

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