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 usually 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 is more than a pipe dream. Most notably, the World Wide Web Consortium’s long-running Semantic Web initiative 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/URI-based grammar for representing diverse entities and their multifaceted relationships.
However, RDF, OWL, and kindred W3C specifications have not exactly taken the service-oriented architecture (SOA) world by storm. 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. And 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 very start, the W3C’s Semantic Web initiative has been more utopian than practical in focus. If you tune into Berners-Lee’s vision, it seems to refer to some sort of supermagical 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 nouveau standards will be adopted universally in the very near future.
Needless to say, this future’s been slow to arrive. Commercial progress on the Semantic Web front has been glacial, at best, with no clear tipping point in sight. It’s been eight years since RDF was ratified by W3C, and more than three years since OWL spread its wings, but neither has achieved breakaway vendor or user adoption. To be fair, there has been a steady rise in the number of semantics projects and start-ups, as evidenced by growing participation in the annual Semantic Technology Conference, which was recently held in
But the SOA market sectors that one would expect to embrace the Semantic Web have largely kept their distance. In theory, vendors of search, enterprise content management, enterprise information integration, enterprise service bus, business intelligence, relational database, master data management, and data quality would all benefit from the ability to automatically harmonize divergent ontologies across heterogeneous environments. But only a handful of vendors from these niches—most notably, Oracle, Software AG, and Composite Software—has taken a visible role in the Semantic Web community, and even these vendors seem to be taking a wait-and-see attitude to it all. One big reason for reluctance is that there are already many established tools and approaches for semantic interoperability in the SOA world, and the new W3C-developed approaches have not yet demonstrated any significant advantages in development productivity, flexibility, or cost.
One of the leading indicators of any technology’s commercial adoption is the extent to which Microsoft is on board. By that criterion, the Semantic Web has a long way to go, and may not get to first base until early in the next decade, at the very least. The vendor’s ambitious roadmap for its SQL Server product includes no mention of the Semantic Web, ontologies, RDF, or anything to that effect. So far, the only mention of semantic interoperability in Microsoft’s strategy is in a new development project codenamed “
Clearly, there is persistent attention to semantic interoperability issues throughout the distributed computing industry, and Microsoft is certainly not the only SOA vendor that is at least pondering these issues on a high architectural plane. The W3C’s Semantic Web initiative may indeed be the seedbed of a new semantics-enabling SOA, though it may take a lot longer for this dream to be fully realized. It may take another generation or so before we see anything resembling a universal semantic backplane that spans all SOA platforms.
After all, the utopian hypertext visions articulated by Vannevar Bush in the 1940s and Ted Nelson in the 1960s had to wait till the 1990s, until Tim Berners-Lee nudged something called the World Wide Web into existence.
More to come.