Links - Semantic Web Examples
Updated: Oct 4 2007
The most complete and developed example of the Semantic Web to date is probably Semantic MediaWiki at ontoworld.org. Note that its vision is in the Wiki on Steriods school of thought, which is one of several overlapping but distinct visions. From the site:
While articles in MediaWiki are just plain texts, SMW allows users to add structured data, comparable to the data one would usually store in a database. SMW uses the fact that such data is already contained in many articles: users just need to "mark" the according places so that the system can extract the relevant data without "understanding" the rest of the text. With this information, SMW can help to search, organise, browse, evaluate, and share the wiki's content.
The Semantic Web Topic Hierarchy provides a good overview of all SemWeb subjects, a very good outline. To see examples of RDF information, follow the links down the People pathway. Al Gore is on the list ( not too big a surprise really ).
Mindswap is of the Semantically Interlinked Communities school and claims to be the first site on the semantic web. They seem to make a good case for it. Note particularly the People page and the wealth of assertions made about the people listed.
For example, picking all assertions about Jen Golbeck ( because she is the first on the list of Mindswap staffers and is also a good example ) will show three columns of data - on the left is the subject ( Jen Golbeck ), in the middle is the predicate ( the relationship to the subject ) and to the right is the object ( the value indicated by the relationship ). The objects are almost exclusively URLS. You may have to use the horizontal scroll bar to see all the information to the right.
If you locate the predicate for "personal mailbox" and then click on the object "mailto:golbeck@cs.umd.edu", it takes you to a resource page for the Email Address type, showing further predicates and objects concerning her personal mailbox. Note that it also has information about the Email Address type and its parent type, Thing . It's possible to get yourself into a spot of trouble at this point so don't click on "Thing", or you will get a gigantic page containing everything. Clicking on "Email Address" gives a relatively small list of email addresses. ( How do they control all the spammers ? ).
It's an interesting site to explore.
Also notable is Googlebase ... included as an example of the Semantic Web more by respect for Google's immense market position and a keen awareness of new trends on the Web than being a good example of the SemWeb. Googlebase supports RDF-style attributes and has some strong SemWeb type features. From the site:
What are attributes?
Google Base lets you describe your items with detailed information called attributes, which will help searchers find your content more easily when they search on various Google properties.
Attributes are words or phrases that help describe the characteristics and qualities of your items. For any given attribute you may enter multiple values separated by commas.
For example: If you're describing a recipe you want to share, your attributes might include 'Theme: Breakfast', 'Main Ingredient: Eggs, Chicken', and 'Servings: 4'.
However, it seems to be under construction for the most part. They may need develop clearer explanations of integration features and the role of various components Certainly, Google will be a major player in whatever emerges under the title of "the Semantic Web".
Swoogle is supported by the UMBC ( University of Maryland Baltimore County ) and calls itself a "Semantic Web Google", and it is in a sense. Swoogle is really a Google of OWL ontologies and searches the links and relationships expressed therein.
A quote from the Swoogle FAQS page of the site:
What does Swoogle do?
Swoogle is a search engine for the Semantic Web on the Web. Swoogle crawl the World Wide Web for a special class of web documents called Semantic Web documents, which are written in RDF. Currently, it provides the following services to the following services:
- search Semantic Web ontologies
- search Semantic Web instance data
- search Semantic Web terms, i.e., URIs that have been defined as classes and properties
- provide metadata of Semantic Web documents and support browsing the Semantic Web. [ link ].
- archive different versions of Semantic Web documents
Currently, Swoogle only indexes some metadata about Semantic Web documents. It neither stores nor searches all triples in an Semantic Web documents as a triple store.
The easiest way to view the ontologies is probably with the Opera Tabulator widget. Also see the page for Swoogle Web Services.