Resource Description Framework RDF

Lesson title: Resource Description Framework RDF
Keywords: RDF, RDF vocabularies, RDF serialization
Objective/Description: In this lesson we will introduce RDF and name some advantages and disadvantages, all of it illustrated by practical examples
Learning outcomes:
- Stating what the Resource Description Framework is about
- Explaining the main elements in RDF
- Illustrating via diagrams the sort of statements that can be modelled with RDF
- Naming the different serializations for RDF graphs
- Naming different ways to syntactically validate RDF data
- Using RDF-XML serialization (and Turtle) to represent knowledge
- Explaining how graph representations can be separated into RDF triples

Resources

PDF
Video

Questions and answers

These Q&A aim to validate a basic understanding of concepts discussed during the lecture. The use of such concepts is beyond the scope of this Q&Astudy set as it is addressed via projects and hands-on for those enrolled in the corresponding university course.

+ Show What are the main specifications used in the Resource Description Framework as a standard model for data interchange on the web?

RDF syntax (rdf), RDF Schema (rdfs) and XSD (xsd).

+ Show Name some possible uses of an rdf:Statement

In general, a statement established a relation (via the predicate) between a subject and an object. Some examples are:
Simple facts: car - is - red,
Database statements: x1 - hasValue - 0.5,
Facts from knowledge bases: Cat - isA - Carnivore,
Distributed information: BlueEye - isUser - Google.

+ Show Name some of the possible notations/formats/serializations for RDF

RDF/XML (based on XML).
RDF/XML Abbrev (also based on XML, less verbose than RDF/XML).
N-triples.
Turtle (commonly more human-readable and less verbose that the others).
JSON-LD (based on JSON, multiple flavors are possible --compacted, extended, flattened).

+ Show How can you test whether your RDF syntax is correct?

There are validations for different notations.

+ Show What are the three elements present in an rdf:Statement?

S-P-O: Subject (rdf:subject), predicate (rdf:predicate) and object (rdf:object).

+ Show What is an rdf:Property useful for?

rdf:Properties allow us to express relations between concepts.

+ Show What sort of rdf:Literal are available?

In general, any sort of string. rdf:Literal can be combined with XSD to express dates, numbers and so.