Kingsley Idehen:This is unfortunate, as it is a prevalent misconception.
The Semantic Web is a broad vision that transcends a broad time spectrum, with regards to the Web's evolution. In addition to the broad spectrum of the vision, there are several technology layers that actually form a "platter of goodies" rather than a "layered cake." The intersection of the vision's timeline, breadth and the assumption that the technology stack is layered 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. I tend to refer to this as the "foundation layer" or "ground zero."
A Web of Linked Data 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 & Resolution scoped to a database record as opposed to 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 limits 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, or as Jim Hendler once stated: I can point to records in your database from mine.
Note that today's Web Data Spaces (social networks, bookmarking services and other shared spaces based on the software as a service) are no different to enterprise 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; the emerging desire on the enterprise front to conceptualize enterprise data via virtualization of heterogeneous data sources also carries over to the Web. The emergence of the Data Portability movement, is an example of the Web community warming to the need for data access virtualization across a plethora of Web Data Silos.
Linked Data addresses the problem of open data connectivity for both the enterprise and the broader Web, by peeling back the data confinement 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 food.yahoo.com. 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.
This article first appeared on internetnews.com.
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