A dereferenceable Uniform Resource Identifier or dereferenceable URI is a resource identification mechanism that uses the HTTP protocol to obtain a representation of the resource it identifies. In the case of Linked Data, the representation takes the form of an information resource that describes the resource that the URI identifies.

Background

Dereferenceable URIs are based on the well established theory and practices of "data access by reference". A data access and manipulation mechanism used extensively in general computer programming (e.g., C/C++ pointers) and database call level interfaces (e.g., ODBC and JDBC) amongst others. The term: dereferencing describes the act of obtaining a representation of a description of an entity via its URI.

In the Semantic Web realm, dereferencable URIs offer the critical fabric that drive the giant global graph of interconnected data popularly referred to as Linked Data; a term also coined by Tim Berners-Lee in his Linked Data Design Note^[1] and furthered by other articles such as "Cool URIs for the Semantic Web" by Sauermann and Cygniak^[2].

Dereferenceable URI Formats

Dereferenceable URIs are constructed using one of two forms: Hash or a Slash. The critical thing about either format is the underlying use of existing Web architecture to preserve the implicit identity (or Pointer) function.

Hash URI Example

Entity Berlin: http://linkeddata.openlinksw.com/about/Berlin#this

Slash URI Example

Entity Berlin: http://dbpedia.org/resource/Berlin

Benefits of a Dereferenceable URI

When an object has a dereferenceable URI, not only does that object have an insignia that can be used across the web, but it also provides a key to unlocking ways of providing more detail and links to relevant information about that object.

Dereferenceable URI's used in this way also enhance OpenID, when not only can the URI be an OpenID but can also provide information about that agent user. The combination of insignia, access to more information and OpenID provides an all round solution for the representation of human users on the Internet.

Summary

In summary we can establish the following facts:

• A dereferenceable URI is a kind of Uniform Resource Identifier (but is accessible via HTTP).
• A dereferenceable URI is a kind of reference (as found in existing computer science theory and practice).

References

Further reading

• Hash vs Slash URI