I just found this interesting Semantic Web effort via '
Danny Ayers' blog. Here is the synopsis from his post:
Piggy Bank 2.0 Beta
New release of Piggy Bank, the Semantic Web extension for Firefox. It harvests data as you browse (when you click a status bar indicator), which can later be searched and viewed in a facetted browser.
The docs have come along some too -
Piggy Bank can collect pure information in the following cases:
1. The web page has invisible link(s) to RDF data (encoded in RDF/XML or N3 formats).
2. The web page exports an RSS feeds.
3. The address of the web page is a file:/ URL pointing to a directory.
4. Piggy Bank has a "screen scraper" [XSLT or Javascript] that can re-structure the web page HTML code into RDF data.
There's a tutorial on writing Javascript screenscrapers on the site, nice touch.
I have also added an architecture diagram to accelerate comprehension (a picture speaks a thousand words...):
The infrastructure for tier-3 is an aspect of
Virtuoso's functionality pool; combining Database & Web Application Server functionality amongst other things, as a single product offering.