Semantic Web

All unapproved Citizendium articles may contain errors of fact, bias, grammar etc. A version of an article is unapproved unless it is marked as citable with a dedicated green template at the top of the page, as in this version of the 'Biology' article. Citable articles are intended to be of reasonably high quality. The participants in the Citizendium project make no representations about the reliability of Citizendium articles or, generally, their suitability for any purpose. This article is currently being developed as part of an Eduzendium student project. The course homepage can be found at CZ:Special_Topics_2010. To provide students with experience in collaboration, you are warmly invited to join in here, or to leave comments on the discussion page. The anticipated date of course completion is 13 August 2010. One month after that date at the latest, this notice shall be removed. Besides, many other Citizendium articles welcome your collaboration!

The Semantic web is a concept, first named by Tim Berners-Lee, for a "web of knowledge" in which world wide web documents' contents would be annotated and classified so that computers can parse the classifications and provide search results based on the semantic information (what the content means), rather than simply on matching of text strings. There is also a W3C standards effort related to this concept.

What differentiates the Semantic Web from existing data structures is the use of URIs to uniquely identify things, and relationships between things. The sort of problem scenario that Semantic Web technologies try to solve are those involving multiple disparate source of data - for instance, hooking together train timetables and class timetables, so a student can automatically plan their travel itinerary without having to manually match the data together.

The W3C have put forward a variety of standards built on top of the Resource Description Framework, a formal semantic model for representing things and the relationships between them.

Domain-specific semantic models

Medicine

Semantic models seem the major trend in expert support to medicine. As an example of how semantic methodologies are used, consider several isolated concepts, which could be considered "nouns":

• beta-adrenergic antagonists (i.e., beta blockers)
• bradycardia (i.e., slow pulse)
• asthma
• hypertension
• benign hand tremor

One of the notations for relationships is the Unified Medical Language System® (UMLS®). Informally, some of the "verb" semantic relationships among the above could be:

• beta-adrenergic antagonists TREAT hypertension and benign hand tremor
• beta-adrenergic antagonists CAUSE bradycardia
• beta-adrenergic antagonists TRIGGER asthma

"Hypertension" would have a number of other TREATS relations, from drug classes such as thiazide diuretics, angiotensin-II converting enzyme antagonists, calcium channel blockers, angiotensin-II receptor blockers, etc.

ULMS is now being extended with formal ontologies:

Semantic Web in CMS

Content management systems (CMS) can benefit greatly from RDF features. RDF is an expressive means by which CMS can both publish and consume data. Because RDF makes data more easily machine readable it is perfect for systems that integrate data (such as CMS).

The Drupal content management system is making a big push to include RDF and semantic web as part of the upcoming Drupal 7 release. There is a Drupal group devoted to semantic web as well as a code sprint devoted to the topic. With over significant and growing market share of CMS, Drupal's support of semantic web will mean a vast increase in implementation of RDF.