RedLeaf Glossary

As we've been reading up on RDF concepts and other implementations, we're finding a lot of ambiguous wording and interchangeable terminology. While some of the terms used in RDF are synonyms, most are not, and shouldn't be used as such. (A node is not a triple, for example.)

As we work, we'll be using the vocabulary as defined by the w3 ​here. We'll be adding to this as needed, and referencing it as code progresses. (Confused about what our class RedLeaf::Node is for? Look here.)

Pieces

Blank node

Functionally equivalent to a wildcard '*', or the concept of 'any'.

Literal

Any value that is not an URI or a Blank node, usually a naked string. A Literal can only be used as a Object in a Statement. It can also contain a language flag or a datatype URI.

Subject

An RDF URI reference or Blank node. The first part of a Statement.

Predicate

An RDF URI reference. The second part of a Triple, that joins the Subject to the Object. Also called Property.

Property

Synonym of Predicate.

Object

An RDF URI reference, Literal, or Blank node. The third part of a Statement.

Putting the pieces together

Nodes

The Subjects and Objects within a Graph.

Statement

A assertion that describes a relationship between two Nodes. Also called a Triple.

|---------|                   |--------|
|         |                   |        |
| subject | ----------------> | object |
|         |     predicate     |        |
|---------|                   |--------|

  (node)         (arc)          (node)

Triple

Synonym of Statement.

Graph

A arbitrary collection of Statements. Also called Model.

Model

Synonym of Graph.