Network Working Group M. Mealling Internet-Draft VeriSign Expires: February 18, 2002 L. Masinter AT&T Labs T. Hardie Equinix G. Klyne Content Technologies Ltd. August 20, 2001 An IETF URN Sub-namespace for Registered Protocol Parameters draft-mealling-iana-urn-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 18, 2002. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract This document describes a new sub-delegation for the 'ietf' URN namespace defined in RFC 2648 for registered protocol items. 1. Introduction From time to time IETF standards require the registration of various Mealling, et. al. Expires February 18, 2002 [Page 1] Internet-Draft IANA URN Namespace August 2001 protocol elements in some well known central repository. The Internet Assigned Numbers Authority maintains this central authority and takes direction from the IETF on what, how and when to add items to that registry. The IANA maintains lists of items such as all assigned port numbers, MIME media types, enterprise numbers, etc. Over time there has developed a need to be able to reference these elements in various schema. In the past this was done in a very adhoc way that easily led to interoperability problems. This document creates a new sub-delegation below the "ietf" [2]URN namespace [1] called 'params' which acts as a standardized mechanism for naming the items registered for IETF standards. 2. Lessons Learned In the process of writing this document, the authors attempted to pre-assign as many names as possible. This involved a complete review of every item currently in the IANA repository. There were several organizational issues that had direct impact on how well a URN could be assigned to particular existing entries in the registry. As a result, the authors have included a set of recommendations that could be made to document authors seeking to setup new registries. 2.1 Multiple Registries Per File The authors found that the practice of putting multiple registries in a single file on the IANA ftp archive caused large amounts of confusion. A good example is the Mobile IP Numbers registry. Due to having several very different concepts in the same file it is very difficult to understand where one set of parameters ends and another begins. The authors recommend that, in the future, the IANA create subdirectories in which each separate registry is maintained in a separate file. Also, document authors are encouraged to suggest a document/directory structure to the IANA in their IANA considerations section. 2.2 Unclear Index Values In many cases the registry had no clearly unique value that could be used in the URN. An example here is the Public Data Network Numbers registry which is a mapping between IP addresses and X.121 addresses. It is not clear which value to use in the name. In recent history the IANA has begun assigning a simple index value to assignments and often this can be used in the URN. Document authors are encouraged to include some type of indexing value in their IANA considerations section so that some other entity can uniquely talk about a particular entry. Mealling, et. al. Expires February 18, 2002 [Page 2] Internet-Draft IANA URN Namespace August 2001 2.3 General Disorganization Due to historical neglect there are several registries that are in a general state of 'disrepair'. The Mobile IP Numbers registry above is a good example. Experts in this area are encouraged to produce new documents providing guidance to the IANA for how these registries should be organized for clarity. 2.4 Obsolete Registries While there have been a few registries that have been marked as obsolete (SGMP Vendor Specific Codes), there is a general lack of a way of moving an IANA registry to historical status. The authors recommend that the IESG create a method by which a document can request that an IANA registry be obsoleted. 3. Changes to RFC 2434 The authors realize that assigning URNs to new items in the registry with no guidance from those asking for the registry is an additional burden the IANA does not need. Thus the authors suggest that the following updates be made to RFC 2434: In the event that an RFC requests that the IANA maintain a registry, the IANA Considerations section of that document MUST include the following: o The top level registry name -- This is the unique string that goes between the third and fourth colons in the URN and is also used as the directory name in any network accessible repositories. For example, the registry name for the Socks Methods is found in the sub-directory called "socks-methods" on the IANA FTP site. This value is also used to assign the URN as "urn:ietf:params:socks- methods:". The requesting document MUST provide this value but the IANA SHOULD follow that recommendation. In the case where there is a conflict the IANA can assign another value. The intent here is that if the registry is simple then this value will be both the filename in which the IANA puts this information and the URN sub-namespace that is created. If the registry is complex and thus has sub-registries, then this value will be the directory name in the FTP archive. o sub-registry names -- In the case where a particular registry has sub-sections then the requesting document MUST provide names for these sub-registries. The intent is that these sub-registry names will be the filenames/sub-directories that exist under the registry directory as well as being the section name in the URN Mealling, et. al. Expires February 18, 2002 [Page 3] Internet-Draft IANA URN Namespace August 2001 that is assigned. The document author should ensure that for each sub-registry there is one and only one set of values and that an index value exists that is unique within that sub-registry. 4. Namespace Specifics Using the template in RFC 2611 as a guide, this is the specification for the 'params' sub-namespace: Sub-namespace name: "params" Declared registrant of the namespace: The Internet Engineering Task Force Declaration of structure: The namespace is primarily opaque. The IANA, as operator of the registry, may take suggestions for names to assign but they reserve the right to assign whatever name they desire, within guidelines set by the IESG. The colon character (":") is used to denote a very limited concept of hierarchy. If a colon is present then the items on both sides of it are valid names. In general, if a name has a colon then the item on the left hand side represents a class of those items that would contain other items of that class. For example, a name can be assigned to the entire list of DNS resource record type codes as well as for each individual code. The URN for the list might look like this: urn:ietf:params:dns:rr-type-codes while the URN for the SOA records type code might look like this: urn:ietf:params:dns:rr-type-codes:soa Mealling, et. al. Expires February 18, 2002 [Page 4] Internet-Draft IANA URN Namespace August 2001 Relevant ancillary documentation: None. Identifier uniqueness considerations: The IANA has sole discretion for assigning names and thus can guarantee uniqueness by comparing the name to be assigned with the list of previously assigned names. Identifier persistence considerations: The IANA has sole discretion for assigning names and thus can guarantee persistence by comparing the name to be assigned with the list of previously assigned names. Process of identifier assignment: Identifiers are assigned only after a particular protocol element or number has been registered with the IANA using standard policies and procedures. Once that element is assigned and in the repository, the IANA will take requests for that element to have a name assigned. The assignment request can suggest a name to use but the IANA may ignore that request. Process of identifier resolution: At this time no resolution mechanism is defined though one is expected. Rules for Lexical Equivalence: Lexical equivalence is achieved by exact string match. Conformance with URN Syntax: There are no additional characters reserved. Mealling, et. al. Expires February 18, 2002 [Page 5] Internet-Draft IANA URN Namespace August 2001 Validation mechanism: None. Scope: Global 5. Assigning Names The authors originally attempted to pre-assign names for every item currently in the repository but found this a) difficult and b) of little current value. The solution is a template and process for requesting that a name by assigned to a particular registry entry. The creation of a new registry name will be simple for most flat registries. The only required elements will be the registry name (see recommended changes to RFC 2434 above), a reference to relevant documents, a statement about which current/proposed document repositories contains the authoritative data for the registry, and a statement specifying which element in the registry is the value to be used in the URN. In most cases this last element will be the index value assigned by the IANA. More complex registries (DNS Parameters for example) will need to repeat that information for any sub-namespaces. It should also be clear as to whether or not a name is assigned to the sub-namespace itself (i.e. is 'urn:ietf:params:dns:rr-types' valid by itself and if so, what does it name?). The template: Registry name: -- The name of the sub-namespace. In many cases this should be the same name as what the registry itself. Specification: -- Relevant IETF published documents that define the registry and the items in it. Repository: -- A pointer to the 'current' location of the registry in the protocol parameters repository. This value will change over time as the entity that maintains the repository moves files and or fileservers. It is not meant as a permanent binding to the filename but as a hint to the IANA for what the initial mapping would be. Mealling, et. al. Expires February 18, 2002 [Page 6] Internet-Draft IANA URN Namespace August 2001 Index value: -- A statement specifying which value in the registry is the index to each entry in that registry. This index value will be used in the URN to name each entry. In some cases it can actually be the thing being named, in others, where those values can change, it should be an index to the record instead of something in the record itself. The process for requesting that a URN be assigned is currently to put the above template in the IANA considerations section of the specifying document. Other more automated processes may be proposed at a latter time if demand requires it. 6. Security Considerations None not already inherent to using URNs. 7. IANA Considerations This document puts a new and significant burden on the IANA since it may require a additional assignment process to happen for each new IANA registry. It is the hope of the authors that the required strictness that the URN assignment puts on the registering document authors will actually make the IANA's job easier by taking the guess work out of creating a new registry. References [1] Moats, R., "URN Syntax", RFC 2141, May 1997. [2] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999. Authors' Addresses Michael Mealling VeriSign 505 Huntmar Park Drive Herndon, VA 22070 US Phone: +1 770 921 2251 EMail: michaelm@netsol.com URI: http://www.verisign.com Mealling, et. al. Expires February 18, 2002 [Page 7] Internet-Draft IANA URN Namespace August 2001 Larry Masinter AT&T Labs 75 Willow Road Menlo Park, CA 94025 US Phone: +1 650 463 7059 EMail: LMM@acm.org URI: http://larry.masinter.net Ted Hardie Equinix 901 Marshall Street Redwood City, CA 94063 US EMail: hardie@equinix.com Graham Klyne Content Technologies Ltd. 1220 Parkview, Arlington Business Park Theale, Reading RG7 4SA UK Phone: +44 118 930 1300 EMail: GK@ACM.ORG Mealling, et. al. Expires February 18, 2002 [Page 8] Internet-Draft IANA URN Namespace August 2001 Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. 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