URN Working Group M.Mealling INTERNET-DRAFT Network Solutions, Inc. Expires six months from June 1998 Intended category: Experimental draft-ietf-urn-net-procedures-00.txt Assignment Procedures for the URI Resolution using DNS (RFC2168) Status of this Memo This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as work in progress. To view the entire list of current Internet-Drafts, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Abstract RFC2168 defines a DNS resource record and an algorithm for using DNS as a registry for retrieving URN authority delegation rules (sometimes called resolution hints). That document specifies that the first step in that algorithm is to lookup the first NAPTR record for the namespace- id in the "urn.net" zone; i.e., the first step in resolving "urn:ietf:rfc:2168" would be to lookup a NAPTR record for the domain "ietf.urn.net". This document describes the procedures for inserting a new rule into this DNS-based URI resolution registry. 1. Introduction In the course of defining a resolution mechanism [RFC2168] according to the rules in RFC2276 [RFC2276] for Uniform Resource Names [RFC2141], it became apparent that the same system could be used to resolve URIs [RFC1738] in the general case. Thus, RFC2168 was specified in such a way as to be generic in its discussions of URNs vs URLs. The end result of this is that RFC2168 defines two things: a Resolver Discovery System registry for URNs and a resolver discovery system for URLs. While this may not seem an important distinction to the casual reader there are some important distinctions in terms of creating new URN namespaces and new URI schemes. Thus, its assignment procedures for the RFC2168 defines registry must adhere to the procedures defined in the assignment documents of both systems. At the same time this document must also define its own procedures, which will ensure its stability and impact on the Domain Name System. These include optimizations such as an extremely long time to live on the values in the urn.net zone and efficient uses of delegations to minimize delegation loops. Mealling [Page 1]
draft-ietf-urn-urn.net-procedures-00.txt June 1998 2. URL Resolution At this time there is no set procedure for registering new URL schemes other than a published RFC. Due to this lack and the existence of non-published schemes such as "about" and "res", there is an IETF working group discussing how to deal with this problem. Thus, at this time the only requirements for requesting an entry in the urn.net zone is that the URL scheme be published or in use somewhere and that it not conflict with an existing URL scheme. When the IETF does standardize a set of procedures for vetting and registering new URL schemes, the urn.net registration procedures MUST adhere to those procedures for determining if the URL scheme in question is valid. 3. URN Resolution RFCXXXX defines the procedures for assignment of new URN namespace-ids. Since the urn.net registration procedures only deal with the namespace-id portion of the URN space, that document is the sole determining document for what can be entered into the urn.net zone for a URN. 4. Delegation Requirements Delegation of a namespace can happen in two ways. In the case of a URL where the entity being delegated to is hard-coded into the identifier itself, the syntax of where this is located is set. In the case where the entity being delegated to is set in the rule, that entity can change as the rule changes. One of the optimizations that the urn.net registry attempts to make is that any entry in that zone should have an extremely long time to live. 'Extremely long' should be measured in years if possible. Thus, any rule that can change must be delegated out of the urn.net zone by a replacement rule in the NAPTR record. For example, the 'foo' URN namespace has flexible rules for how delegation takes place. Instead of putting those rules in the urn.net zone, the entry instead punts those rules off to a nameserver that has a shorter time to live. The record in urn.net would look like this: foo IN NAPTR 100 10 "" "" "" urn-resolver.foo.com. Thus, when the client starts out in the resolution process, the second step is to begin asking 'urn-resolver.foo.com' for the NAPTR records that contain the resolution rules. Conversely, the 'http' URL scheme adheres to a particular syntax that specifies that the host to ask is specified in the URL in question. Since this syntax does not change, that rule can be specified in the urn.net zone. The record would look like this: http IN NAPTR 100 100 "" "" "/http:\\/\\/([^\\/:]+)/\\2/i" . Mealling [Page 2]
draft-ietf-urn-urn.net-procedures-00.txt June 1998 Thus, the second step of resolution is to attempt to contact the host contained in the URL itself. 5. Submission Procedure Using the MIME Content-Type registration mechanism [RFC2048] as a model for a successful registration mechanism, the urn.net procedure consists of a request template submitted to a open mailing list made up of interested parties. If no objections are made within a two week period, a representative of the urn.net registration authority considers the submission to be accepted and enters that submission into the nameserver. At this time the registration authority is expected to be the IANA. Objections are restricted to those that point out impacts on the urn.net zone itself or to DNS in general. Objections to the URL scheme or to the URN namespace-id are not allowed, as these should be raised in their respective forums. The logical conclusion of this is that ANY sanctioned URL scheme or URN namespace MUST be allowed to be registered if it meets the requirements specified in this document as regards times to live and general impact to the DNS. Updating a record in the urn.net zone also requires that the same process to be followed. Since urn.net is designed with a long time to live, changes to records in that zone are discouraged. Thus updates must follow the same procedures as a new request. Changes will be given a higher level of scrutiny, as they may represent potential problems with a specific delegation. 6. Registration Template The template to be sent to the list MUST contain the following values: 6.1 Type Either SCHEME or NID. SCHEME specifies that the record being registered represents a URL scheme. NID specifies that it is a URN namespace-id. 6.2 Key This is the domain portion. It must be valid according to the procedures specified in the URN namespace-id assignment document and any future standards for registering new URL schemes. 6.3 Authority This is the authority doing the registration of the record. It must be an authority recognized as either the IESG or an authority specified in the documents submitted for approval by any URN or URL registration mechanism. Mealling [Page 3]
draft-ietf-urn-urn.net-procedures-00.txt June 1998 6.4 Records One or more records representing the rule set for the key. The required values are Preference, Order, Flags, Services, Regex, and Replacement as defined by RFC2168. 7. Example Template To: register@urn.net From: joe@foo.com Type: NID Key: foo Authority: Foo Technology, Inc as specified in RFCFOO Record: foo IN NAPTR 100 100 "" "" "" urn.foo.com. 8. IANA Considerations This document describes a mechanism for registering representations of protocol items that have already been registered with some IETF sanctioned agency (probably the IANA as well). This means that the IANA need not determine appropriateness of the underlying namespaces, since that is determined by another process. The only real impact on the IANA will be: to maintain (or designate some other entity to maintain) a primary nameserver for the urn.net zone; to maintain the mailing list "register@urn.net" as the forum for discussions of submissions; and to act as the party that determines if all objections have been noted and accommodated. 7. References [RFC2168] Ron Daniel & Michael Mealling, "Resolution of Uniform Resource Identifiers using the Domain Name System", RFC 2168, June 1997. [RFC2276] K. Sollins, "Architectural Principles of Uniform Resource Name Resolution", RFC 2276, January 1998. [RFC2141] Ryan Moats, "URN Syntax", RFC 2141, May 1997. [RFC1738] T. Berners-Lee, L. Masinter and M. McCahill, "Uniform Resource Locators (URL)" RFC 1738, December 1994. <URL:ftp://ftp.internic.net/rfc/rfc1738.txt> [RFC2048] N. Freed, J. Klensin, J. Postel, "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures", RFC 2048, November 1996. Mealling [Page 4]
draft-ietf-urn-urn.net-procedures-00.txt June 1998 8. Author Contact Information Michael Mealling Network Solutions 505 Huntmar Park Drive Herndon, VA 22070 voice: (703) 742-0400 fax: (703) 742-9552 email: michaelm@rwhois.net This document expires 6 months from June, 1997 Mealling [Page 5]
