W3C issues RDF and OWL Recommendations

Background

The Web was designed for people to read. A page's markup tells a browser how to display text and images but says little about what that text means, so software cannot reliably tell what a page is about or how its data relates to data elsewhere. The Semantic Web idea was to add descriptions that machines could process: statements about what a thing is, what it is connected to, and what rules apply to it. Two specifications do most of that work — one for writing the descriptions, one for building vocabularies with enough logic for a computer to reason over them.

What happened

On 10 February 2004 the World Wide Web Consortium announced final approval of two key Semantic Web technologies: the revised Resource Description Framework (RDF) and the Web Ontology Language (OWL)^[1]. Both were issued as W3C Recommendations. In W3C's usage, a Recommendation is what industry and the Web community understand as a Web standard — a stable specification developed by a Working Group and reviewed by the W3C Membership^[1]. Approval therefore marked the end of drafting and review, and the point at which the specifications were put forward as standards.

The two pieces

RDF is the simpler of the two. It expresses data as short statements about resources, so that separate systems can describe the same thing in the same shape and combine their descriptions without a custom translation for every pair of databases. OWL works one level up: it is a language for ontologies, explicit vocabularies of classes, relations and constraints, written so that software can check descriptions for consistency and infer facts that were never stated outright. W3C summed up the pair as providing a framework for asset management, enterprise integration and the sharing and reuse of data on the Web^[1].

Key details

The OWL Recommendation was not a single document. The OWL Overview records its status as W3C Recommendation of 10 February 2004 and names Deborah L. McGuinness of Stanford University and Frank van Harmelen of the Vrije Universiteit Amsterdam as editors^[2]. The Overview is one of six parts of the OWL Recommendation, developed by the Web Ontology Working Group for publication on that date^[2].

W3C director Tim Berners-Lee said RDF and OWL make a strong foundation for Semantic Web applications, and noted that their approval came at a time when new products were springing up in areas as diverse as enterprise integration and medical decision support^[1].

Eric Miller, W3C Semantic Web Activity Lead, described the work as continuity rather than rupture: the Semantic Web is more Web Evolution than Revolution, he said, made through incremental changes that bring machine-readable descriptions to data and documents already on the Web^[1].

What it changed

W3C said the announcement marked the emergence of the Semantic Web as a broad-based, commercial-grade platform for data on the Web^[1]. That claim rested on the status of the documents rather than on any single product: a Recommendation is a stable specification that vendors can build against, and the two specifications together cover both how data is written down and what can be inferred from it. Miller's framing points at where the change was expected to show up — not in a new Web replacing the old one, but in descriptions attached to pages and datasets that were already there.