Resolution of Uniform Resource Identifiers using the Domain Name System
RFC 2168
Document | Type |
RFC - Experimental
(June 1997; No errata)
Updated by RFC 2915
Was draft-ietf-urn-naptr (urn WG)
|
|
---|---|---|---|
Authors | Ron Daniel , Michael Mealling | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 2168 (Experimental) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group R. Daniel Request for Comments: 2168 Los Alamos National Laboratory Category: Experimental M. Mealling Network Solutions, Inc. June 1997 Resolution of Uniform Resource Identifiers using the Domain Name System Status of this Memo =================== This memo defines an Experimental Protocol for the Internet community. This memo does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited. Abstract: ========= Uniform Resource Locators (URLs) are the foundation of the World Wide Web, and are a vital Internet technology. However, they have proven to be brittle in practice. The basic problem is that URLs typically identify a particular path to a file on a particular host. There is no graceful way of changing the path or host once the URL has been assigned. Neither is there a graceful way of replicating the resource located by the URL to achieve better network utilization and/or fault tolerance. Uniform Resource Names (URNs) have been hypothesized as a adjunct to URLs that would overcome such problems. URNs and URLs are both instances of a broader class of identifiers known as Uniform Resource Identifiers (URIs). The requirements document for URN resolution systems[15] defines the concept of a "resolver discovery service". This document describes the first, experimental, RDS. It is implemented by a new DNS Resource Record, NAPTR (Naming Authority PoinTeR), that provides rules for mapping parts of URIs to domain names. By changing the mapping rules, we can change the host that is contacted to resolve a URI. This will allow a more graceful handling of URLs over long time periods, and forms the foundation for a new proposal for Uniform Resource Names. Daniel & Mealling Experimental [Page 1] RFC 2168 Resolution of URIs Using the DNS June 1997 In addition to locating resolvers, the NAPTR provides for other naming systems to be grandfathered into the URN world, provides independence between the name assignment system and the resolution protocol system, and allows multiple services (Name to Location, Name to Description, Name to Resource, ...) to be offered. In conjunction with the SRV RR, the NAPTR record allows those services to be replicated for the purposes of fault tolerance and load balancing. Introduction: ============= Uniform Resource Locators have been a significant advance in retrieving Internet-accessible resources. However, their brittle nature over time has been recognized for several years. The Uniform Resource Identifier working group proposed the development of Uniform Resource Names to serve as persistent, location-independent identifiers for Internet resources in order to overcome most of the problems with URLs. RFC-1737 [1] sets forth requirements on URNs. During the lifetime of the URI-WG, a number of URN proposals were generated. The developers of several of those proposals met in a series of meetings, resulting in a compromise known as the Knoxville framework. The major principle behind the Knoxville framework is that the resolution system must be separate from the way names are assigned. This is in marked contrast to most URLs, which identify the host to contact and the protocol to use. Readers are referred to [2] for background on the Knoxville framework and for additional information on the context and purpose of this proposal. Separating the way names are resolved from the way they are constructed provides several benefits. It allows multiple naming approaches and resolution approaches to compete, as it allows different protocols and resolvers to be used. There is just one problem with such a separation - how do we resolve a name when it can't give us directions to its resolver? For the short term, DNS is the obvious candidate for the resolution framework, since it is widely deployed and understood. However, it is not appropriate to use DNS to maintain information on a per-resource basis. First of all, DNS was never intended to handle that many records. Second, the limited record size is inappropriate for catalog information. Third, domain names are not appropriate as URNs. Therefore our approach is to use DNS to locate "resolvers" that can provide information on individual resources, potentially including the resource itself. To accomplish this, we "rewrite" the URI into a domain name following the rules provided in NAPTR records. Rewrite rules provide considerable power, which is important when trying toShow full document text