How the Semantic Web would work
Rensselaer project papplies RDF to Data.gov to create new datasets
The concept of a Semantic Web, in which data is linked via machine-readable formats, is still far from reality, but some organizations and researchers are making progress.
At the recent International Semantic Web Conference, researchers from the Rensselaer Polytechnic Institute demonstrated how they re-rendered all the data from the Office of Management and Budget’s Data.gov Web sites into the Resource Description Framework. Their work was partially funded by grants from the Defense Advanced Research Projects Agency and National Science Foundation.
"Our goal is to make the whole thing shareable and replicable for others to reuse," said project researcher Li Ding.
Rendering data into RDF, which is used to create the Linked Data necessary to the Semantic Web, can make it easier to interpose it with other sets of data to create entirely new datasets and visualizations, Ding said. He showed a Google Map graphic that interposed RDF versions of two different data sources from the Environmental Protection Agency, originally rendered in CSV files.
The graphic derives the new material by linking common elements from the two datasets, Ding said. The map shows the levels of ozone depletion across the country, and the severity of the depletion is marked by the circumference of the bubbles over the area where the readings were taken. One dataset contained the ozone readings while the other data source contained the geographical locations where the readings were taken. The map data was created by joining these two sets of data by using their common element — the names of the locations where the readings took place.
At least some systems that the government is now setting up could be easily adapted to RDF.
One example is the White House's recent deployment of the Drupal open-source content management system for its Web site.
David Lantner, editor of the "Clear Type Press" blog, noted that Drupal will give the White House a good start in annotating its data in a machine-readable way, if the managers choose to do so. Drupal's use of RDF "enables authors to add semantic metadata…to their markup using attributes that are both machine-readable and human-friendly," Lantner wrote.
At the ISWC conference, Stephane Corlosquet, a former researcher at the National University of Ireland's Digital Enterprise Research Institute, demonstrated a set of four interrelated new modules he helped develop for Drupal to ease the use of RDF. The modules were written to "expose the site structure in an RDF format automatically, so site administrators or users don't have to care about RDF or do anything with RDF," he said.
"Drupal has a very modular design, so we can plug [the modules] into the system very easily," Corlosquet said. He said these modules will be incorporated into the next core version of the system, Drupal 7.