Ubiquitous semantic interoperability is like world peace: It's a goal so grandiose, nebulous and contrary to the fractious realities of distributed networking that it hardly seems worth waiting for.

In most circumstances we can assume that heterogeneous applications will employ different schemas to define semantically equivalent entities — such as customer data records — and that some sweat equity will be needed to define cross-domain data mappings for full interoperability.

Nevertheless, many smart people feel that automated, end-to-end, standards-based semantic interoperability (where computers exchange not just data but the data's meaning as well) is more than a pipe dream. Most notably, the long-running Semantic Web initiative of the World Wide Web Consortium (W3C) just keeps chugging away, developing specifications that have fleshed out Tim Berners-Lee’s vision to a modest degree and gained a smidgen of real-world adoption.

If nothing else, the W3C can point to the Resource Description Framework (RDF) — the first and most fundamental output from this W3C activity — as a solid accomplishment. Created just before the turn of the millennium, RDF — plus the closely related Web Ontology Language (OWL) — provides an XML- and Uniform Resource Identifier (URI)-based grammar for representing diverse entities and their multifaceted relationships.

RDF, OWL and kindred W3C specifications have not exactly taken the service-oriented-architecture (SOA) world by storm, however. In fact, you’d be hard-pressed to name a single pure-play vendor of Semantic Web technology that’s well known to the average enterprise IT professional.

Also rare is the enterprise IT organization that’s looking for people with backgrounds in or familiarity with Semantic Web technologies. This remains an immature, highly specialized niche in which academic research projects far outnumber commercial products and in which most products are point solutions rather than integrated features of enterprise databases, development tools and application platforms.

Part of the problem is that from the start, the focus of W3C’s Semantic Web initiative has been more Utopian than practical. If you tune into Berners-Lee’s vision, it seems to refer to some sort of super-magical metadata, description and policy layer that will deliver universal interoperability by making every networked resource automatically and perpetually self-describing on every conceivable level. Alternately, it seems to call for some sort of XML-based tagging vocabulary that everybody will apply to every scrap of online content, thereby facilitating more powerful metadata discovery, indexing and search. The success of the whole Semantic Web project seems to be predicated on the belief that these nouveaux standards will be adopted universally in the very near future.