ftp.cc.uoc.gr
rfc6588
This is a purely informative rendering of an RFC that includes verified errata. This rendering may not be used as a reference.

The following 'Verified' errata have been incorporated in this document: EID 3188, EID 3189
Internet Engineering Task Force (IETF)                       C. Ishikawa
Request for Comments: 6588                 YRP Ubiquitous Networking Lab
Category: Informational                                       April 2012
ISSN: 2070-1721


                       A URN Namespace for ucode

Abstract

   This document describes a Uniform Resource Name (URN) namespace for
   ucode, an identifier system for objects and places.  ucode technology
   is used in many applications, and this document provides a URN
   namespace for ucode to enable its use in Internet-related devices and
   software.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6588.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   ucode [UCODE] is an identifier to be stored in many types of tags
   (not limited to Radio Frequency Identification (RFID) tags).  Its
   allocation and management is handled by the Ubiquitous ID Center
   [UIDC].  The embedding of ucode in many types of tags (RFID tags,
   optical code, infrared markers, and even sound source) is also
   specified by the Ubiquitous ID Center.

   The basic length of ucode is 128 bits, but it is extensible in units
   of 128 bits if necessary.

   ucode has been devised to identify objects and places where existing
   standards do not fit the application needs or the scope of the
   applications or where the allocation policy of existing standards is
   too limited for Small and Medium Enterprises (SMEs), small-scale
   research laboratories at academic institutions, or individual users.

   Applications that use ucode take advantage of the Internet
   extensively.  Use of ucode is open to anybody.  Those who wish to
   have ucode allocated can do so either by having ucode subspace
   allocated to them directly from the Ubiquitous ID Center [UIDC] or by
   obtaining tags that have pre-stored ucode from so called "providers"
   [UCDMIP].  Such tags are certified as ucode tags [UIDTAG], and the
   reader specifications are published so that there will be many
   readers available for such tags.

   By having a URN for ucode, we can facilitate the use of ucode in many
   Internet-related devices and software for the benefit of existing and
   future users of ucode and people who will access such tags attached
   to objects and places.  Since an application based on ucode can run
   across organizational boundaries and spread across regions and
   countries, a formal URN Namespace Identifier (NID) assignment for
   'ucode' is requested.

2.  'ucode' Registration Template

   Namespace ID:

   'ucode' requested

   Registration Information:

   Registration Version Number: 1
   Registration Date: 2011-12-21

   Declared registrant of the namespace:

   T-Engine Forum
   2-20-1, Nishi-Gotanda
   Shinagawa, Tokyo, 141-0031
   Japan
   office@t-engine.org
   Tel: +81-3-5437-0572

      Declaration of syntactic structure: 

   The structure of the namespace for 'ucode' using the hexadecimal
   representation of the identifier is as follows using ABNF [RFC5234].

   UCODE-URN    = "urn:ucode:" ucode-name
   ucode-name   = "_" ucode-number
   ucode-number = 1*ucode-value
|  ucode-value  = 32UCHEXDIG
|  UCHEXDIG     = %x30-39 / 0x41-46   ; digits 0..9, uppercase A..F
|
EID 3188 (Verified) is as follows:

Section: 2, pg.3

Original Text:

   Declaration of syntactic structure:

   The structure of the namespace for 'ucode' using the hexadecimal
   representation of the identifier is as follows using ABNF [RFC5234].

   UCODE-URN = "urn:ucode:" ucode-name
   ucode-name = "_" ucode-number
   ucode-number = 1*ucode-value
   ucode-value = 32HEXDIG
   HEXDIG         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
   DIGIT          =  %x30-39
                  ; 0-9

Corrected Text:

   Declaration of syntactic structure:

   The structure of the namespace for 'ucode' using the hexadecimal
   representation of the identifier is as follows using ABNF [RFC5234].

   UCODE-URN    = "urn:ucode:" ucode-name
   ucode-name   = "_" ucode-number
   ucode-number = 1*ucode-value
|  ucode-value  = 32UCHEXDIG
|  UCHEXDIG     = %x30-39 / 0x41-46   ; digits 0..9, uppercase A..F
|
Notes:
Note: The above clause is part of the 'ucode' URN Namespace
Registration Template, so the above correction needs
to be applied to the template archived at IANA as well.

Rationale: The maintainers of the namespace intended to admit
only uppercase letters in the hexadecimal representation,
in order to accomodate usage of assigned <ucode-value>s in
case-sensitive XML context; this is specified in other parts
of the RFC, but should be specified also in the formal definition.
According to the ABNF Standard, RFC 5234, string literals in ABNF
are explicitly case-insensitive (cf. page 5 of RFC 5234).
NOTE 1: "1*" at the start of the ucode-number definition is not a typo. Although the currently used ucode [UCODE] is 128 bits (16 octets), thus requiring 32 hexadecimal characters to represent serially, ucode is designed to be extensible in increments of 128 bits. So, in the distant future, we may need to repeat the chunks of 128 bits. This is why "1*" precedes ucode-value. NOTE 2: ucode-name starts with a "_" because it is also intended to be used as an identifier for XML [W3CXML]. Because an XML tag can't start with a digit, an "_" (underscore) is inserted at the beginning to make sure ucode-name starts with a non-digit. For example, the 128-bit ucode value 0123456789ABCDEF0123456789ABCDEF, expressed in a series of hexadecimal digits, is as follows: urn:ucode:_0123456789ABCDEF0123456789ABCDEF Relevant ancillary documentation: ucode, the identifier expressed by ucode-number, is managed by the Ubiquitous ID Center [UIDC], which is a sub-organization of the T-Engine Forum [TEF]. The document "Ubiquitous Code: ucode" [UCODE] defines this identifier system. Identifier uniqueness considerations: The 'ucode' namespace is managed by the Ubiquitous ID Center. The Ubiquitous ID Center assigns the identifier, ucode, in such a way that the uniqueness of the 'ucode' namespace will be maintained. Identifier persistence considerations: The assignment process guarantees that names are not reassigned and that the binding between the name and its resource is permanent, regardless of any standards or organizational changes or the assignment period. Process of identifier assignment: Names are assigned by the Ubiquitous ID Center and by any entities that are sub-delegated by the Ubiquitous ID Center. This assignment process is based on "ucode Management Implementing Procedures" [UCDMIP] established by the Ubiquitous ID Center. Process of identifier resolution: The process of identifier resolution is currently based on the "ucode Resolution Protocol" [UCSURP]. It will be enhanced by using newer recommendations from ITU-T and/or standards from ISO. Rules for lexical equivalence: | The Namespace-Specific String (NSS) in 'ucode' URNs | (i.e. the <ucode-name> in the ABNF) is case-sensitive. | So this namespace imposes no additional lexical equivalences | beyond what is specified in RFC 2141 (i.e., according to | RFC 2141, the "urn:ucode:" part is case-insensitive, the NSS | is not).
EID 3189 (Verified) is as follows:

Section: 2, pg.4

Original Text:

   Rules for lexical equivalence:

   The entire UCODE-URN is case-sensitive.

   NOTE: This is an additional restriction imposed on the ucode
   namespace by the requirements of some major applications of ucode in
   existence.  Only capital "A", "B", "C", ..., "F" are allowed as part
   of hexadecimal characters.

Corrected Text:

   Rules for lexical equivalence:

|  The Namespace-Specific String (NSS) in 'ucode' URNs
|  (i.e. the <ucode-name> in the ABNF) is case-sensitive.
|  So this namespace imposes no additional lexical equivalences
|  beyond what is specified in RFC 2141 (i.e., according to
|  RFC 2141, the "urn:ucode:" part is case-insensitive, the NSS
|  is not).
Notes:
Note: The above clause is part of the 'ucode' URN Namespace
Registration Template, so the above correction needs
to be applied to the template archived at IANA as well.

Rationale: The RFC text violates Section 5 of RFC 2141, which
specifies that the case-insensitivity of the URI Scheme ("URN")
and the URN Namespace ID (NID) cannot be overridden by a URN
Namespace registration.
It was the intent of the maintainers of the 'ucode' namespace
to follow RFC 2141, but the language in the RFC has happened
to indicate otherwise.

The correction of the ABNF recorded in Errata Note #3188 makes
the original NOTE superflous, since the corrected ABNF now
precisely specifies what this NOTE intended to superimpose on
the original ABNF in the RFC.
Conformance with URN syntax: There are no special reserved characters. The URN of this namespace conforms to RFC 2141 [RFC2141] and RFC 3986 [RFC3986]. Validation mechanism: No special considerations. Scope: Global. 3. IANA Considerations One URN Namespace registration for 'ucode' (46) has been entered into the IANA "Formal URN Namespaces" sub-registry for URN NIDs. 4. Namespace Considerations ucode, the identifier expressed by ucode-number, is a unique identification number to identify a tangible object or a place. Additionally, ucode can be assigned to "content" or "information" that does not exist in the real world or a "concept" that is yet more abstract. ucode has been devised to identify objects and places where existing standards do not fit the application needs or the scope of the applications or where the allocation policy of existing standards is too limited for SMEs, small-scale research laboratories at academic institutions, or individual users. ucode is only an identification number, and its value (or its sub- bitfields) does not contain any pre-assigned meaning. Any relevant information about the object or place to which a ucode is assigned is stored in a data server that can be reached after a "resolution process" [UCSURP]. This resolution process usually occurs over the Internet. ucode can be assigned to an object to be identified regardless of the type of application. ucode is expected to be stored in any kind of tags (2D optical code, RFID, etc.), and it provides a framework where anyone can obtain unique numbers for identification purposes. ucode has been designed to provide the services outlined in ITU-T Recommendation F.771 [ITU-T-F771] and to operate in the framework of ITU-T Recommendation H.621 [ITU-T-H621]. ucode architecture is general enough to cover many applications for the users. 5. Community Considerations This namespace enables ucode to be stored in tags that are designed to store URN. Also, ucode-related information can be described as metadata using the URN namespace. Thus, the namespace facilitates the exchange of descriptions regarding objects and places among multiple organizations. It is expected that many small-scale providers will offer ucode tags to small users and that large scale providers will hand out millions of tags to users. The resolution servers and applications will be available to general users with appropriate access control over the Internet. The published specification for resolver and access services for 'ucode' allows the creation of client software for many types of computers including small mobile terminals and ever-popular smartphones. 6. Security Considerations There are no additional security considerations other than those normally associated with the use and resolution of URNs in general. 7. References 7.1. Normative References [UCODE] T-Engine Forum, Ubiquitous ID Center, "ucode: Ubiquitous Code", UID-00010, <http://www.uidcenter.org/spec#UID-00010>. [UCDMIP] T-Engine Forum, Ubiquitous ID Center, "ucode Management Implementing Procedures", UID-00034, <http://www.uidcenter.org/spec#UID-00034>. [UCSURP] T-Engine Forum, Ubiquitous ID Center, "Simplified ucode Resolution Protocol", UID-00005, <http://www.uidcenter.org/spec#UID-00005>. [UIDTAG] T-Engine Forum, Ubiquitous ID Center, "ucode Tag Architecture", UID-00017, <http://www.uidcenter.org/spec#UID-00017>. [RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. [ITU-T-F771] ITU-T, "Service description and requirements for multimedia information access triggered by tag-based identification", ITU-T Recommendation F.771, <http://www.itu.int/rec/T-REC-F.771-200808-I>. [ITU-T-H621] ITU-T, "Architecture of a system for multimedia information access triggered by tag-based identification", ITU-T Recommendation H.621, <http://www.itu.int/rec/T-REC-H.621-200808-I>. 7.2 Informative References [W3CXML] W3C, "Extensible Markup Language (XML) 1.1", <http://www.w3.org/TR/xml11/>. [UIDC] Ubiquitous ID Center, <http://www.uidcenter.org/>. [TEF] T-Engine Forum, <http://www.t-engine.org/>. 8. Acknowledgments The author would like to thank Peter Saint-Andre, the Document Shepherd/Responsible Area Director for this document, for providing valuable suggestions. The author would also like to thank the following people who helped to improve this document: Adrian Farrel David Harrington Pete Resnick Stephen Farrel Ted Hardie Wesley Eddy The author would also like to thank the members of T-Engine Forum who have built prototype and real-world applications using ucode and offered valuable feedback. Application examples from these members can be found on the Ubiquitous ID Center web site [UIDC] and on www.youtube.com (search for "uidcenter" without the quotes). 9. Contributors Ken Sakamura Noboru Koshizuka Katsunori Shindo Tomonori Usaka Past and current members of the uID architecture group at the University of Tokyo and the YRP Ubiquitous Networking Laboratory (YRP UNL) Author's Address Chiaki Ishikawa YRP Ubiquitous Networking Laboratory 2-20-1, Nishi-Gotanda Shinagawa, Tokyo, 141-0031 Japan Tel: +81-3-5437-2270 FAX: +81-3-5437-2271 EMail: chiaki.ishikawa@ubin.jp