URN (Uniform Resource Name): Identifier for Unique Resources

Uniform Resource Name (URN) is a specific type of Uniform Resource Identifier (URI) that names a resource uniquely without providing its location.

A Uniform Resource Name (URN) is a specific type of Uniform Resource Identifier (URI) that uniquely identifies a resource without specifying its location. Think of it as a persistent, location-independent identifier assigned to a resource to ensure its unique identification.

What is URN?

Definition

A Uniform Resource Name (URN) is an identifier for resources that does not specify a method to locate them. Unlike URLs (Uniform Resource Locators), which provide both the identity and the location of a resource, URNs are designed to serve as persistent, location-independent resource identifiers.

Characteristics

URNs are part of a broader concept known as URIs (Uniform Resource Identifiers). A URN has certain characteristics:

• Permanence: The identity of the resource remains constant, even if the resource itself moves or undergoes changes.
• Resolution Independence: It does not provide a method for locating the resource, only identifying it.

Types of URNs

Examples

URNs are used across various applications. Some examples include:

• ISBN: urn:isbn:0451450523 identifies a book by its International Standard Book Number.
• URI vs. URL vs. URN: It is noteworthy to compare different types of URIs:
  • URL: http://example.com/resource (specifies a location)
  • URN: urn:example:resource (specifies an identity without location)

Special Considerations

When implementing URNs, consider:

• Namespaces: A URN is divided into a Namespace Identifier (NID) and a Namespace Specific String (NSS), for example, urn:isbn:0451450523. Proper namespace management is crucial.
• Persistence: URNs are designed to be long-lived. This requires careful planning and coordination.

Historical Context

The concept of URNs was first introduced to deal with the increasing necessity to identify digital resources with persistent, location-independent names. URNs are defined in RFC 2141, developed by the Internet Engineering Task Force (IETF).

Applicability

Use Cases

URNs are utilized in many fields:

• Libraries and Publishing: Identifiers such as ISBNs and ISSNs.
• Scientific Research: Unique identifiers for datasets and research papers.
• Digital Object Identifiers (DOIs): Frequently used in academic publishing.

Comparison with Related Terms

It’s important to differentiate between URNs and other related terms:

• URI: A generic term for identifiers, which includes URLs and URNs.
• URL: An identifier that also provides a location.
• URN: A type of URI that specifies a resource’s identity without indicating its location.

FAQs

What is the difference between a URI and a URN?

A URI is a generic identifier that can include URLs and URNs. A URN specifically focuses on identifying a resource without specifying its location.

Can a URN be used to locate a resource?

No, a URN does not include information about the location of the resource. It only provides a unique identifier.

How are URNs maintained?

URNs require careful management of namespaces to ensure their persistence and uniqueness.

References

1. RFC 2141 - URN Syntax
2. Internet Society. “Uniform Resource Names (URNs).” Retrieved from https://www.internetsociety.org/resources/doc/urn

Summary

A Uniform Resource Name (URN) is a unique identifier for a resource that does not specify how to locate it. URNs ensure persistent, location-independent identification, pivotal for resource management in various industries, including libraries, publishing, and scientific research.

Understanding the scope and application of URNs helps ensure efficient and reliable resource management, offering a robust solution for the challenges of digital resource identification.