Format/indirect-link
From LDTables Wiki
An indirect-link is a normal HTML hypertext link used to identify some conceptual entity by linking to some web content about that entity. For example, in a table of information about commercial airports, the airports can be identified using indirect-links to some public pages about each airport. This allows easier automatic integration of data.
If a link is not an indirect-link, it is usually a direct-link, which identifies some Web resource itself, such as a document or video. Thus the URL http://en.wikipedia.org/wiki/Henry_V_%28play%29 can be used as an indirect-link to identify Shakespeare's famous 1599 play, or as a direct link to identify a Wikipedia web page about that play. The URL http://en.wikipedia.org/wiki/Henry_V_of_England, used as an indirect-link identifies a king of England; used as a direct link, it identifies another Wikipedia page. Finally, the URL http://shakespeare.mit.edu/henryv/full.html, as a direct link, identifies a web page containing the entire text of Shakespeare's play.
A good indirect-link leads to content which is stable and precise about what it exactly it describes. Wikipedia pages tend to be fairly good for this. Many web pages do not have a clear and unambiguous subject. For example if we use that ...full.html URL, above, as an indirect-link, are we identifying the human being King Henry V of England, the somewhat fictionalized Henry V portrayed in that play, or, more abstractly, the stories and themes conveyed in that play? In general, content authors are encouraged, when making indirect-links, to use only page which are clearly describing a particular conceptual entity.
See the special property self-link, which can be used to establish the connection between a table entry and the item described in that entry, by way of an indirect-link.
[edit] Examples
| Example Values | Corresponding item in the value space |
|---|---|
| Tim Berners-Lee, the person, himself | |
| George Washington, the first president of the US. | |
| The San Francisco International Airport, identified through the official governmental page | |
| The San Francisco International Airport, identified through its wikipedia page |
@@ bad examples?
[edit] Mapping to RDF
Since RDF has only direct links, when converting indirect-link data to RDF, a "TDB" URL of some sort must be created. Options include the proposed tdb: URI scheme, and the http://thing-described-by.org/ service. Probably the best option, at this point, is a tdb service that does content negotiation and can do format conversion. In particular, when a GET is done, instead of just 303-redirecting to the content, it could redirect to a service where it provides the data in the requested format. This service translate Linked Data Table data to RDF/XML, for example.
