GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc4078

Network Working Group N. Earnshaw Request for Comments: 4078 BBC Research and Development Category: Informational S. Aoki

                                                  TokyoFM Broadcasting
                                                             A. Ashley
                                                           NDS Limited
                                                           W. Kameyama
                                               GITS, Waseda University
                                                              May 2005
         The TV-Anytime Content Reference Identifier (CRID)

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2005).

Abstract

 The Uniform Resource Locator (URL) scheme "CRID:" has been devised to
 allow references to current or future scheduled publications of
 broadcast media content over television distribution platforms and
 the Internet.
 The initial intended application is as an embedded link within
 scheduled programme description metadata that can be used by the home
 user or agent to associate a programme selection with the
 corresponding programme location information for subsequent automatic
 acquisition.
 This document reproduces the TV-Anytime CRID definition found in the
 TV-Anytime content referencing specification, and is published as an
 RFC for ease of access and registration with the Internet Assigned
 Numbers Authority (IANA).

Earnshaw, et al. Informational [Page 1] RFC 4078 TV-Anytime CRID May 2005

Table of Contents

 1. Introduction ....................................................2
 2. Ancestry ........................................................3
 3. Notation Used in This Document ..................................3
 4. The CRID URL Scheme .............................................3
 5. Examples of CRID Syntax .........................................4
 6. Usage ...........................................................4
    6.1. Normative Specification ....................................4
    6.2. Role of Domain Name System (DNS) Namespace .................5
    6.3. CRID Resolving .............................................5
    6.4. CRID Related Metadata ......................................5
 7. IANA Considerations .............................................6
    7.1. General ....................................................6
    7.2. Registration Template in Accordance with RFC 2717 ..........6
 8. Security Considerations .........................................7
 9. Acknowledgements ................................................7
 10. References .....................................................8
     10.1. Normative References .....................................8
     10.2. Informative References ...................................8

1. Introduction

 In recent years there has been an expansion in the number of
 broadcast television and radio services available to the home.  In
 addition to the broadcast services delivered over traditional
 distribution channels such as Digital Terrestrial, Satellite and
 Cable, the advent of high-speed Internet connection will give rise to
 even more information and entertainment services, providing audio-
 visual programme material sourced directly to the home over the
 Internet.
 Alongside this expansion there has also been increased growth in
 complexity of devices available to the home user, which will allow
 the user to operate in a 'search-select-acquire' paradigm.  In this
 model, the user or user agent uses descriptive information about
 audio visual programmes as a basis for selecting the programme for
 subsequent acquisition and viewing.  Increasingly, home appliances
 are being furnished with local storage, enabling the automatic
 capture of programme material through off-air recording or
 downloading by a home appliance.
 The 'CRID:' Uniform Resource Locator is designed to be the bridge
 between programme-related descriptive metadata and corresponding
 programme location data that may be published over a different
 distribution network or at a different time.

Earnshaw, et al. Informational [Page 2] RFC 4078 TV-Anytime CRID May 2005

 Programme location data provides the home user agent with the
 information required to acquire the programme at the time of
 publication.  In the case of the television distribution model, these
 locators provide programme broadcast timing and tuning information so
 that the user appliance can record the programme when it is broadcast
 in real time.  In the case of Internet delivery, the locators have to
 be of the form associated with streaming protocols or file exchange
 protocols with the time (or time window) of availability indicated.
 Because a content publisher may release audio-video material in the
 same form on a number of platforms or repeatedly over some time
 interval, the CRID can be used to aggregate these different
 publications and associate them with a single description.
 Furthermore, there may be other meaningful semantic associations
 between otherwise unrelated programme publications with assigned CRID
 that can be further aggregated under a higher-level CRID.  This
 higher-level CRID can be described through its own descriptive
 metadata.  The subjective nature of these aggregation decisions is
 part of the CRID authoring process and is not standardised.
 The CRID resolution process ultimately enabling the user agent to
 acquire audio-visual programme material may be a timely process, with
 resolution updates delivered dynamically from the service provider.
 This is to reflect common business practice of adjusting the time of
 content availability close to the original published time to
 accommodate a live, managed, reactive broadcast service.

2. Ancestry

 The Uniform Resource Locator scheme 'CRID:' is taken from the
 TV-Anytime forum Content Reference Identifier and is a result of the
 consensus reached by members of this forum between March 2000 and
 June 2002.  The TV-Anytime CRID and associated supporting data is
 specified in the TV-Anytime Phase 1 Content Referencing Specification
 [TVA-CR].

3. Notation Used in This Document

 The notation used in this document takes the form
             <first>/<second>
 in which the component names are in angle brackets and any characters
 outside angle brackets are literal separators.

Earnshaw, et al. Informational [Page 3] RFC 4078 TV-Anytime CRID May 2005

4. The CRID URL Scheme

 The CRID URL takes the form
             crid://<DNS name>/<data>
 in which <DNS name> is a registered Internet domain name that takes
 the form of domain name described in Section 3 of [RFC1034] and
 Section 2.1 of [RFC1123].
 <data> is a free format string that is URI [RFC3986] compliant, and
 that is meaningful to the authority given by the authority field.
 The portion of the field is case insensitive.  It is recommended that
 all characters not within the range of characters allowed in a URI
 must be encoded into UTF-8 and included in the URI as a sequence of
 escaped octets.  An escaped octet is encoded as a character triplet,
 consisting of the percent character, "%", followed by the two
 hexadecimal digits representing the octet code.
 In its entirety, the CRID is URI compliant as specified in [RFC3986].
 As per [RFC3986], the crid:// part of the syntax is case insensitive.

5. Examples of CRID Syntax

 The following are examples of a valid CRID:
          crid://example.com/foobar
 The above CRID was created by "example.com" authority, with data part
 of foobar:
          crid://example.co.jp/%E3%82%A8%E3%82%A4%E3%82%AC
 The above CRID was created by "example.co.jp" authority, with a data
 part of "E", "I", and "GA" (meaning "movie"), represented as KATAKANA
 LETTERS (Japanese characters) in UTF-8 encoding preceded by "%".

6. Usage

6.1. Normative Specification

 The Uniform Resource Locator scheme 'CRID:' identifies the URL as the
 TV-Anytime Content Reference Identifier and conforms to the TV-
 Anytime Content Referencing Specification [TVA-CR].  The TV-Anytime
 CRID is a key component in the TV-Anytime forum specification series
 as described in the informative overview Systems Description
 Specification [TVA-Sys].  The normative Content Referencing
 Specification [TVA-CR] also includes the details of the contents and

Earnshaw, et al. Informational [Page 4] RFC 4078 TV-Anytime CRID May 2005

 format of the associated content referencing tables that resolve the
 TV-Anytime CRID into further CRID instances or transport system-
 dependent locations.

6.2. Role of Domain Name System (DNS) Namespace

 Note that the use of the registered Internet Domain does not mean
 that the DNS resolving service is to be employed for the resolution
 of CRID URL.  Indeed the resolution information is fully specified in
 [TVA-CR] and does not require the use of the DNS resolution service.
 This is especially important as one key application area is broadcast
 television and radio distribution services that are not Internet
 based.
 In business scenarios that exploit Internet connectivity to the home,
 the DNS portion of the CRID can be used to resolve the Internet
 location of the service provider, who in turn will provide location
 resolution information in a form described in [TVA-CR].

6.3. CRID Resolving

 As addressed in [TVA-CR], the CRID is ultimately resolved either
 directly by the CRID authority or by another party.  If another party
 is providing resolution, the ability to resolve the CRID requires the
 flow of some information from the authority to the resolution
 provider, in order to tie the CRID to its resolution.  Examples of
 relationships between CRID authors and the suppliers of resolution
 information are given in [TVA-Sys].
 As described in [TVA-CR], there will in all likelihood be more than
 one CRID that can resolve directly or indirectly to a given single
 locator at a given time.
 Also shown in [TVA-CR], CRIDs that resolve directly to the location
 of the scheduled content are likely to resolve to more than one
 location, as television and radio programmes are often published
 repeatedly within broadcast schedules or across different broadcast
 services or distribution platforms over an extended period of time.

6.4. CRID Related Metadata

 TV-Anytime specification [TVA-Met] specifies the format and contents
 of the programme-related descriptive metadata designed to convey the
 TV-Anytime CRID for the purpose outlined here, as well as that of
 other data supporting the publication and usage of programme
 material.

Earnshaw, et al. Informational [Page 5] RFC 4078 TV-Anytime CRID May 2005

7. IANA Considerations

7.1. General

 The 'crid:' URI scheme is reserved to designate that the URI relates
 to the TV-Anytime CRID and is to be used in accordance with the
 TV-Anytime Content Referencing Specification [TVA-CR].
 The designation of the value of each CRID is the responsibility of
 the CRID author, as identified through the 'authority' field.
 The policy of assignment of CRID values lies with the CRID author
 associated with the authority field.  It is likely that there will be
 a number of diverse (and possibly changing) authoring policies as
 required by various organisations as they address their respective
 audiences.  These individual policies will address resolution target
 resource designation issues such as the subjective equivalence of
 programme material available from different locations, the grouping
 of CRIDs under another CRID for collective description and resolution
 purposes, the cross referencing of CRID between authorities, CRID
 lifetime, and CRID reuse.
 It is likely that some authoring policies may be set through
 collaborative business arrangements, localised operational
 agreements, or national governmental bodies.

7.2. Registration Template in Accordance with [RFC2717]

 URL scheme name: crid
 URL scheme syntax: See Section 4
 Character encoding considerations: TV-Anytime does not specify the
 character encoding scheme to be adopted by each implementation.
 However, in the case where Internet interoperability is desired, it
 is recommended that all characters not within the range of characters
 allowed in a URI must be encoded into UTF-8 and included in the URI
 as a sequence of escaped octets.  An escaped octet is encoded as a
 character triplet, consisting of the percent character, "%", followed
 by the two hexadecimal digits representing the octet code.  For
 example, the character A would be represented as "A", the character
 LATIN CAPITAL LETTER A WITH GRAVE would be represented as "%C3%80",
 and the character KATAKANA LETTER A would be represented as
 "%E3%82%A2".
 Intended Use: See Section 6
 Application and protocols which use this scheme: See Section 6

Earnshaw, et al. Informational [Page 6] RFC 4078 TV-Anytime CRID May 2005

 Interoperability considerations: None (Section 4 contains the first
 version of the CRID URL definition)
 Security considerations: See Section 8
 Relevant publications: See [TVA-CR], [TVA-Met], [TVA-Sys], [TVA-Prt]
 Contact: Wataru KAMEYAMA, Vice Chairman and Secretary of the TV-
 Anytime Forum, wataru@waseda.jp
 Author/Change controller: IESG

8. Security Considerations

 The CRID URL described here provides a referencing mechanism.  The
 values of the URL contain the authoring 'Authority' name as a DNS
 namespace identifier and a data portion to distinguish it from other
 CRIDs from the same authority.  There should be no reason to prevent
 disclosure of the values within the CRID and no commercial
 sensitivity associated with these values.
 When the binding conveyed as part of a larger data set which may have
 commercial value or critical binding between a CRID and the
 accompanying data, the security and integrity of the binding is a
 matter for the wider system implementers to judge and protect
 accordingly.  One such method for protecting metadata can be found in
 [TVA-Prt], though it is not mandated that users adopt this.  In any
 case, there may be other, wider system security functions in place or
 such precautions may not be seen as necessary.
 Tampering with values of CRIDs during transmission or distribution
 over public or open networks has only nuisance or denial-of-service
 effects unless it causes alternative location resolution data or
 programme metadata to be referenced.  Again, this can be dealt with
 as a system delivery of data integrity issue not specific to the
 CRID.
 Impersonating a CRID authority by authoring CRID with an authority
 portion for which the bogus author does not have permission from the
 registered DNS name holder would be a misuse of the DNS name holder's
 identity and should be dealt with through normal business practice.

9. Acknowledgements

 The authors would like to acknowledge the support of the members of
 the TV-Anytime forum and their work in the development of the TV-
 Anytime CRID.

Earnshaw, et al. Informational [Page 7] RFC 4078 TV-Anytime CRID May 2005

10. References

10.1. Normative References

 [TVA-CR]   European Telecommunications Standards Institute, "ETSI TS
            102 822-4 v1.1.2 ; Broadcast and On-line Services: Search,
            select and rightful use of content on personal storage
            systems ("TV-Anytime Phase 1"); Part 4: Content
            referencing", October 2004.
 [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
            RFC 1034, November 1987.
 [RFC1123]  Braden, R., "Requirements for Internet Hosts - Application
            and Support", RFC 1123, October 1989.
 [RFC2717]  Petke, R. and I. King, "Registration Procedures for URL
            Scheme Names", RFC 2717, November 1999.
 [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
            Resource Identifier (URI): Generic Syntax", STD 66, RFC
            3986, January 2005.

10.2. Informative References

 [TVA-Sys]  European Telecommunications Standards Institute, "ETSI TS
            102 822-2 v1.2.1 ; Broadcast and On-line Services: Search,
            select and rightful use of content on personal storage
            systems ("TV-Anytime Phase 1").  Part 2 System
            Description", September 2004.
 [TVA-Met]  European Telecommunications Standards Institute, "ETSI TS
            102 822-3-1 v1.2.1 ; Broadcast and On-line Services:
            Search, select and rightful use of content on personal
            storage systems ("TV-Anytime Phase 1").  Part 3 Metadata.
            Sub-part 1: Metadata Schemas", September 2004.
 [TVA-Prt]  European Telecommunications Standards Institute, "ETSI TS
            102 822-7 v1.1.1 ; Broadcast and On-line Services: Search,
            select and rightful use of content on personal storage
            systems ("TV-Anytime Phase 1").  Part 7 Bi-directional
            Metadata Delivery Protection", October 2003.

Earnshaw, et al. Informational [Page 8] RFC 4078 TV-Anytime CRID May 2005

Authors' Addresses

 Nigel Earnshaw
 BBC Research and Development
 Kingswood Warren
 Tadworth, Surrey  KT20 6NP
 United Kingdom
 Phone: +44 1737 839618
 EMail: nigel.earnshaw@rd.bbc.co.uk
 Shigeru Aoki
 TokyoFM Broadcasting
 1-7 Kojimachi
 Chiyoda-ku, TOKYO  102-8080
 JAPAN
 Phone: +81 3 3221 0244
 EMail: shig@center.jfn.co.jp
 Alex Ashley
 NDS Limited
 One London Road
 Staines, Middlesex  TW18 4EX
 United Kingdom
 Phone: +44 208 4768270
 EMail: aashley@ndsuk.com
 Wataru Kameyama
 GITS, Waseda University
 1011 Okuboyama, Nishi-tomida
 Honjo-shi, SAITAMA  367-0035
 JAPAN
 Phone: +81 495 24 6052
 EMail: wataru@waseda.jp

Earnshaw, et al. Informational [Page 9] RFC 4078 TV-Anytime CRID May 2005

Full Copyright Statement

 Copyright (C) The Internet Society (2005).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
 This document and the information contained herein are provided on an
 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Intellectual Property

 The IETF takes no position regarding the validity or scope of any
 Intellectual Property Rights or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
 this document or the extent to which any license under such rights
 might or might not be available; nor does it represent that it has
 made any independent effort to identify any such rights.  Information
 on the procedures with respect to rights in RFC documents can be
 found in BCP 78 and BCP 79.
 Copies of IPR disclosures made to the IETF Secretariat and any
 assurances of licenses to be made available, or the result of an
 attempt made to obtain a general license or permission for the use of
 such proprietary rights by implementers or users of this
 specification can be obtained from the IETF on-line IPR repository at
 http://www.ietf.org/ipr.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights that may cover technology that may be required to implement
 this standard.  Please address the information to the IETF at ietf-
 ipr@ietf.org.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Earnshaw, et al. Informational [Page 10]

/data/webs/external/dokuwiki/data/pages/rfc/rfc4078.txt · Last modified: 2005/05/18 17:14 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki