Uniform Resource Name (URN) in Transport Layer

The transport layer is the important layer in the OSI reference model. A URN is a uniform resource identifier that provides a way of uniquely naming a resource without specifying an access protocol or mechanism, and without specifying a particular location.

Uniform Resource Name (URN):

Basically, URN is the string of characters i.e. name to identify the intended resource. The URN identifies the resource by the name in the given name-space. It is location-independent.URN is a type of Uniform Resource Identifier (URI). It is the subset of URI.

URN allows the descriptive information to associate with it called the Uniform Resource Characteristics(URC). Some URCs of URN are a date, length, etc. The user only needs to know the name of the resource to use the URN. URNs are persistent.URN requires a resolution service to convert names into real addresses.

URN format:

"urn :" <NID> " : " <NSS>

<NID> is the Namespace Identifier and <NSS> is the Namespace Specific String.

Examples of URN : 

urn : efg : // abcd   
Here, efg : // is the namespace identifier 
and abcd is namespace specific string.
urn : pqr : // xyz      
Here , pqr : //  is the namespace identifier 
and xyz is namespace specific string.

In the first example, efg: // can be an accessible directory for all dictionaries and encyclopedias on the Internet. abcd was the name of the term. Whereas in the example, 2 pqr: // can be an accessible directory to all dictionaries and encyclopedias on the Internet. xyz was the name of the term.

Using the namespace identifiers results in the best definition or the longest definition of the namespace-specific string it can find on the Internet.