Linked Data Leaders: The Semantic Web Is Here

Two Linked Data visionaries say the standards are in place and the Semantic Web vision is a reality — you just have to know where to look.
Posted June 10, 2008

Dan Muse

To paraphrase the immortal words of Ferris Bueller, the World Wide Web moves moves pretty fast. If you don't stop and look around once in awhile, you could miss it.

LinkedData Planet

If you haven't been looking around lately, you might just miss the next evolutionary stage of the Web — the Semantic Web or Linked Data movement promises to change the way software developers, enterprises and consumers interact with data.

The technology driving the Semantic Web and Linked Data will be on display on June 17 -18 at the LinkedData Planet conference in New York. "The adoption by business of semantics technology is producing a new generation of applications, sometimes known as Web 3.0 and Enterprise 2.0," said Ken North, co-chair for the conference.

North said that the lineup of speakers at LinkedData Planet reflects the conference theme: the confluence of Web and enterprise computing.

Sir Tim Berners-Lee, the director of the World Wide Web Consortium and the man who introduced the concept of the Semantic Web several years ago, will deliver one of the conference's keynote addresses.

Other speakers include Berners-Lee's colleagues Rensselaer Polytechnic Institute Professor James Hendler and OpenLink Software CEO Kingsley Idehen, who North called a thought leader of the Linked Data movement. North said Hendler, Idehen and others have advocated linking data as an important step in evolving the Web - a process of moving from a web of linked documents to a web of linked data.

To get a better perspective of where thing are heading with the Semantic Web and Linked Data movements, we posed questions about standards and adoption to Hendler and Idehen.

Q. Given that the Semantic Web is largely based on participants adhering to standards, do you think the standard bodies (such as W3C and IETF) are keeping pace with companies and developers?

James Hendler: I'm not sure I agree with this at all: The Semantic Web isn't defined by the standards, the standards follow the work in the field. The 2001 Scientific American article on the Semantic Web ([which] Tim Berners-Lee, Ora Lassila and I wrote) came out several years before the first standards.

That said, the standards bodies don't have the job to lead, their job is to provide a forum for companies to agree on what they need for interoperability. The set of standards maintained by the W3C Semantic Web [...] has been growing quite fast, with GRDDL, RDFa, SPARQL and others coming along.

Kingsley Idehen
"Linked Data allows us to look at data from a range of perspectives, by peeling back the containment of a Web site, Web page, database, or database table. It sets the records free, by bringing the entities that records represent to life."
— Kingsley Idehen

Kingsley Idehen: Yes [they are keeping pace]. In actual fact they [the standard bodies] are ahead most of the time.

The Semantic Web is an example of the standardization process being way ahead of the roadmaps of companies and developers.

Q. Are the standard bodies adequately responsive to real-world needs?

James Hendler: I think so. Recall that they are a consortia driven by the needs of their members.

Kingsley Idehen: Very much so. I do sometimes wonder if companies are adequately responsive to the emergence and evolution of standards, though.

Q. Are they doing a good job of educating content producers and software developers about standards? That is, will the standards help drive the technology or will the technology drive the standards at this point?

James Hendler: That is not really the job of a standards [consortium]. Their job is to do enough education to get things going. The successful standards generate enough interest to be picked up by the educational market in things like O'Reilly books, books on ideas (like the recent "Semantic Web for the Working Ontologist").

Kingsley Idehen: Usage patterns, in response to the quest for value, trigger the evolution of technology. Of course, the evolution of technology then triggers the need for standardization.

James Hendler
"When people first started to learn about the Web, they needed to learn about "hyperlinks" and "markup." Web 2.0 developers have to learn about Ajax, services and social network mathematics. Should Web 3.0 be any different?"
— James Hendler

Q. Is commercial consideration of good SEO driving content producers to follow better practices in terms of their markup, too. That is, is Google having an educational benefit by virtue of rewarding good markup and more structured data?

James Hendler: Google is not yet talking in public about work with the Semantic Web and these particular approaches to metadata. The smaller companies playing in areas like Semantic Search are showing real potential, and some of the other large companies, that compete with Google are exploring the space (with rumors of buyouts and takeovers afloat).

Remember, at this point, we're primarily talking about data interoperability and not search, and the large data companies (Oracle, IBM and Microsoft) all have people and products in this space.

Kingsley Idehen: No. I don't put Google-induced SEO in the same bucket as, say, constructive addition of structure to the Web. Put differently, Google-induced SEO optimizations more often than not reduce the serendipitous discovery of relevant things on the Web.

Linked Data on the Web is about structured data on the Web where granularity goes right down to the level of individual entities (e.g., people, places, events, subject matter, books, music, photos, tags and so on.)

Q. When someone interested in exploring the Semantic Web first starts looking around, he or she might find himself/herself facing a collection of unfamiliar technologies that seem to make it harder to produce "good" content and that concern themselves with unfamiliar concepts like "ontologies" and "knowledge domains."

James Hendler: When people first started to learn about the Web they, needed to learn about "hyperlinks" and "markup." Web 2.0 developers have to learn about Ajax, services, and social network mathematics. Each new Web technology brings new things with it and the leading developers push these forward, with others learning after. Should Web 3.0 be any different?

Kingsley Idehen: This is unfortunate, as it is a prevalent misconception.

The Semantic Web is a broad vision that transcends a broad time spectrum regarding the evolution of the Web. In addition to the broad spectrum, there are several technology layers. The intersection of the vision's timeline breadth and the layered technology offerings has lead to a lot of confusion, to put things mildly.

At the current time, Linked Data is the part of the Semantic Web vision that is most relevant and demonstrable, value-wise.

A Web of Linked is simply about the application of Web architecture to the time-tested concept of "Data Access by Reference." It is about publication, derivation and dissemination of structured data that exposes discrete entities that exploit the prowess of the HTTP protocol for Naming and Name Resolution. Linked Data is not different (conceptually) to Open Database Connectivity (ODBC) or Java Database Connectivity (JDBC) when exploring the subject of Data Access by Reference. What Linked Data offers over ODBC or JDBC is the ability to provide Data Source Naming scoped to a database record as opposed to just the database or database table levels. In addition, the use of HTTP extends the data access reference scope beyond the confines of traditional data access constraints such as DBMS vendor engine, dbms schema, host operating system, network protocol, network topology, local area networks and so on.

You have direct access to records across the Web, internal Intranets or custom extranets. As Jim Hendler once stated: I can point to records in your database from mine.

Note, that today's Web Spaces (social networks, bookmarking services and other shared spaces based on the software as a service) are no different to dnterprise databases that sit behind DBMS vendors' Call Level Interfaces (DBMS vendor APIs) and/or SOA-style Web Services. We are talking about the same thing in different realms. Thus, the emerging desire on the enterprise front to conceptualize enterprise data via virtualization heterogeneous data sources also carries over to the Web. There is a growing need, as expressed via the Data Portability movement, for the same conceptual mode access to virtualized data sources across a plethora of Web Data Silos.

Linked Data solves the problem for the enterprise and the broader Web, concurrently It allows us to look at data from a range of perspectives, by peeling back the containment of a Web site, Web page, database or database table. It sets the records free by bringing the entities that records represent to life.

Q. If you wanted to provide a bewildered but still curious novice a public example of Linked Data at work in their everyday life, what would it be?

James Hendler: Point them at It's already out there, it's just not obvious.

Kingsley Idehen:

My Linking Open Data community Profile Page - the Linked Data integration is exposed via the "Explore Data" Tab.

My Linked Data Space - viewed via OpenLink's AJAR (Asynchronous Javascript and RDF) based Linked Data Brower.

In both cases, you have the ability to explore my data spaces by simply clicking on the links, which on the surface appear to be standard hypertext links. In reality, you are dealing with hyperdata links (i.e., links to entities that result in the generation of entity description pages that expose entity properties via hyperdata links). Thus, you have a single page that describes me in a very rich way since it encompasses all data associated with me, covering personal profile, blog posts, bookmarks, social networks and so on.

Q. What would you show the CEO or CTO of a company outside the tech industry?

James Hendler: I would show them RadarNetworks Twine (note, I'm on the advisory board), MetaWeb, Garlik and other sites that already have thousands of users and are generating ROI. If they are in the financial, pharmaceutical or government areas, I would show them a number of specialized products where people are making money off these technologies.

The Semantic Web isn't about annotation of the current Web — that's one small piece — and the data side story is out there, growing and doing extremely well.

Kingsley Idehen: A link to the Entity ALFKI, from the popular Northwind Database associated with Microsoft Access and SQL Server database installations.

This particular link exposes a typical enterprise data space (orders, customers, employees, suppliers ...) in a single page. The hyperdata links represent intricate data relationships common to most business systems that will ultimately seek to repurpose existing legacy data sources and SOA services as Linked Data.

Alternatively, I would show the same links via the Zitgist Data Viewer (another Linked Data-aware browser). In both cases, I am exploiting direct access to entities via HTTP due to the protocols incorporation into the Data Source Naming scheme.

Tags: Google, search, virtualization, semantic Web, semantic

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