More In This Article
Editor's Note: We are posting this feature from our December 2007 issue because of a discussion on the semantic web at ScienceOnline09.
Six years ago in this magazine, Tim Berners-Lee, James Hendler and Ora Lassila unveiled a nascent vision of the Semantic Web: a highly interconnected network of data that could be easily accessed and understood by any desktop or handheld machine. They painted a future of intelligent software agents that would head out on the World Wide Web and automatically book flights and hotels for our trips, update our medical records and give us a single, customized answer to a particular question without our having to search for information or pore through results.
They also presented the young technologies that would make this vision come true: a common language for representing data that could be understood by all kinds of software agents; ontologies—sets of statements—that translate information from disparate databases into common terms; and rules that allow software agents to reason about the information described in those terms. The data format, ontologies and reasoning software would operate like one big application on the World Wide Web, analyzing all the raw data stored in online databases as well as all the data about the text, images, video and communications the Web contained. Like the Web itself, the Semantic Web would grow in a grassroots fashion, only this time aided by working groups within the World Wide Web Consortium, which helps to advance the global medium.
Since then skeptics have said the Semantic Web would be too difficult for people to understand or exploit. Not so. The enabling technologies have come of age. A vibrant community of early adopters has agreed on standards that have steadily made the Semantic Web practical to use. Large companies have major projects under way that will greatly improve the efficiencies of in-house operations and of scientific research. Other firms are using the Semantic Web to enhance business-to-business interactions and to build the hidden data-processing structures, or back ends, behind new consumer services. And like an iceberg, the tip of this large body of work is emerging in direct consumer applications, too.
Just below the Surface The Semantic Web is not different from the World Wide Web. It is an enhancement that gives the Web far greater utility. It comes to life when people immersed in a certain field or vocation, whether it be genetic research or hip-hop music, agree on common schemes for representing information they care about. As more groups develop these taxonomies, Semantic Web tools allow them to link their schemes and translate their terms, gradually expanding the number of people and communities whose Web software can understand one another automatically.
Perhaps the most visible examples, though limited in scope, are the tagging systems that have flourished on the Web. These systems include del.icio.us, Digg and the DOI system used by publishers, as well as the sets of custom tags available on social sites such as MySpace and Flickr. In these schemes, people select common terms to describe information they find or post on certain Web sites. Those efforts, in turn, enable Web programs and browsers to find and crudely understand the tagged information—such as finding all Flickr photographs of sunrises and sunsets taken along the coast of the Pacific Ocean. Yet the tags within one system do not work on the other, even when the same term, such as “expensive,” is used. As a result, these systems cannot scale up to analyze all the information on the Web.
The World Wide Web Consortium—an ad hoc organization of more than 400 companies and universities co-hosted by the Massachusetts Institute of Technology in the U.S., the European Consortium for Informatics and Mathematics in France, and Keio University in Japan—has already released the Semantic Web languages and technologies needed to cross such boundaries, and large companies are exploiting them. For example, British Telecom has built a prototype online service to help its many vendors more effectively develop new products together. Boeing is exploring the technologies to more efficiently integrate the work of partners involved in airplane design. Chevron is experimenting with ways to manage the life cycle of power plants and oil refineries. MITRE Corporation is applying Semantic Web tool kits to help the U.S. military interpret rules of engagement for convoy movements. The U.K.’s national mapping agency, Ordnance Survey, uses the Semantic Web internally to more accurately and inexpensively generate geographic maps.
Other companies are improving the back-end operations of consumer services. Vodafone Live!, a multimedia portal for accessing ring tones, games and mobile applications, is built on Semantic Web formats that enable subscribers to download content to their phones much faster than before. Harper’s Magazine has harnessed semantic ontologies on its Web site to present annotated timelines of current events that are automatically linked to articles about concepts related to those events. Joost, which is putting television on the Web for free, is using Semantic Web software to manage the schedules and program guides that viewers use online.