Network Working Group A. Adolf
Request for Comments: 5328 Micronas GmbH
Category: Informational P. MacAvock
 DVB Project
 September 2008
 A Uniform Resource Name (URN) Namespace for
 the Digital Video Broadcasting Project (DVB)
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.
Abstract
 This document describes a Uniform Resource Name (URN) namespace for
 the Digital Video Broadcasting Project (DVB) for naming persistent
 resources defined within DVB standards. Example resources include
 technical documents and specifications, eXtensible Markup Language
 (XML) Schemas, classification schemes, XML Document Type Definitions
 (DTDs), namespaces, style sheets, media assets, and other types of
 resources produced or managed by DVB.
Table of Contents
 1. Introduction ....................................................2
 2. Specification Template ..........................................2
 3. Examples ........................................................4
 4. Namespace Considerations ........................................4
 5. Community Considerations ........................................7
 6. Security Considerations .........................................9
 7. IANA Considerations .............................................9
 8. References .....................................................10
 8.1. Normative References ......................................10
 8.2. Informative References ....................................11
1. Introduction
 The Digital Video Broadcasting Project (DVB) is an industry-led
 consortium of over 270 broadcasters, manufacturers, network
 operators, software developers, regulatory bodies and others in over
 35 countries committed to designing global standards for the global
 delivery of digital television and data services. Services using DVB
 standards are available on every continent with a total of more than
 100 million DVB receivers already deployed.
 DVB would like to assign unique, permanent, location-independent
 names based on URNs for some resources it produces or manages. These
 URNs will be constructed according to the URN syntax defined in
 [RFC2141].
 This namespace specification is for a formal namespace to be
 registered according to the procedures set forth in [RFC3406].
2. Specification Template
 This section provides the information required to register a formal
 namespace according to the registration procedure defined in
 [RFC3406]. The URNs conform to the syntax defined in [RFC2141].
 Namespace ID:
 "dvb"
 Registration Information:
 Version: 1
 Date: 2007年02月28日
 Declared registrant of the namespace:
 Name: Peter MacAvock
 Title: Executive Director, DVB Project Office
 Affiliation: DVB Digital Video Broadcasting
 Address: Ancienne Route 17a
 CH-1218 Geneva
 SWITZERLAND
 Phone: +41 22 717 2719
 Email: macavock@dvb.org
 Declaration of structure:
 URNs assigned by DVB will have the following hierarchical
 structure based on the organizational structure of the DVB
 standards:
 urn:dvb:<NSS>
 where the syntax of "<NSS>" is specified in Section 2.2 of the URN
 Syntax requirements ([RFC2141]).
 The individual URNs will be assigned by DVB through the process of
 development of DVB standards.
 Relevant ancillary documentation:
 None
 Identifier uniqueness considerations:
 DVB will establish unique identifiers as appropriate.
 Uniqueness is guaranteed as DVB ensures through its
 standardization process that an assigned string is never
 reassigned.
 Identifier persistence considerations:
 DVB is committed to maintaining the accessibility and persistence
 of all resources that are officially assigned URNs by the
 organization.
 Process of identifier assignment:
 Assignment is limited to DVB and those authorities that are
 specifically designated by DVB. DVB may designate portions of its
 namespace for assignment by other parties under its regime.
 Process of identifier resolution:
 DVB will develop and maintain "URN catalogues" that map all
 assigned URNs to Uniform Resource Locators (URLs) specifically to
 enable Web-based resolution of named resources. In the future, an
 interactive online resolution system may be developed to automate
 this process. The latest information about DVB-defined metadata
 can always be found on the DVB website at:
 http://www.dvb.org/metadata
 DVB will authorize additional resolution services as appropriate
 and in-line with the DVB standardization process.
 Rules for Lexical Equivalence:
 The "<NSS>" is case insensitive.
 Conformance with URN Syntax:
 No special considerations.
 Validation mechanism:
 None specified. DVB will develop and maintain URN catalogues.
 The presence of a URN in a catalogue indicates that it is valid.
 Scope:
 Global
3. Examples
 The following examples are not guaranteed to be real. They are
 presented for pedagogical reasons only.
 urn:dvb:ipdc:esg:2005
 urn:dvb:cs:ZappingTypeCS:2001
4. Namespace Considerations
 The urn:dvb namespace is used to identify metadata that is defined by
 DVB and describes DVB multimedia and interactive services. The
 registration of urn:dvb as a formal namespace enables the use and
 referencing of DVB XML fragments in other standards worldwide and
 enables those standards to leverage and build upon publicly available
 DVB metadata schemas and fragments.
 These URNs are used to refer to, in conjunction with, and as part of
 commercial or public multimedia broadcast services. In most markets,
 these are under the control of a national regulator. So if a
 particular market chooses to use DVB services, in general, the
 regulator imposes compliance with the relevant DVB specifications to
 ensure interoperability and open competition in the marketplace.
 URN assignment procedures:
 The individual URNs shall be assigned through the process of
 development of DVB standards by the Digital Video Broadcasting
 Project (DVB). The latest information about DVB defined metadata
 can always be found at the owner's website at:
 http://www.dvb.org/metadata
 URN resolution/delegation:
 The resolution and delegation shall be determined through the
 process of development of DVB standards by the Digital Video
 Broadcasting Project (DVB).
 Since the implementations envisaged cover a wide range of devices
 with quite different access methods and capabilities, no single
 resolution or delegation mechanism can be referenced in this
 document.
 Currently, 2 client system classes are covered by DVB
 specifications:
 o A broadcast set-top box that only has a unidirectional,
 receive-only connection. Hence, all DVB URNs need to be
 resolvable from the service discovery information received in
 the broadcast stream.
 o A "home network end device" (HNED) that could be an IPTV set-
 top box, networked TV, or personal digital recorder with an
 Ethernet or Wireless Local Area Network (WLAN) connection to a
 home gateway device.
 Further device classes will be addressed as DVB standardization
 progresses. The urn:dvb URNs must however remain valid. DVB will
 define appropriate resolution/delegation mechanisms to ensure that
 DVB URNs remain valid for those new device classes as well.
 For the two above example device classes, 3 ways of conveying such
 resolution information are currently defined by DVB:
 o Repeated, cyclic transmission of Resolution Authority Records
 (RAR) and Resolution Records (RR) as auxiliary data in digital
 TV broadcast streams over satellite, cable, or terrestrial
 transmissions according to [EN300468], [EN301192], and
 [TS102323].
 o Repeated, cyclic multicast transmission of Resolution Records
 (RR) via the DVBSTP protocol according to [TS102034].
 o Unicast delivery of Resolution Records (RR) in response to HTTP
 "GET /dvb/sdns" requests according to [TS102034].
 Type of resources to be identified:
 Types of resources to be identified include XML schema definition
 files, classification schemes, and identification systems defined
 and openly published by DVB. These resources being identified
 constitute a metadata system to describe digital multimedia
 broadcast services or content conveyed as part of such services.
 The latest DVB defined metadata can always be found at:
 http://www.dvb.org/metadata
 These metadata definitions are not entirely usable without
 knowledge of the DVB specifications listed in the Normative
 References section. To make them generally useful for client
 platforms typically found in computer network environments today,
 XSLT transformations to HTML, or other common formats would be
 needed to enable rendering in a standard web browser. On the
 other hand, it is expected that with the increasing overlap
 between the computer and multimedia worlds - e.g., with the
 forthcoming DVB file format definition - DVB metadata formats will
 get adopted in player implementations on PC platforms as well.
 Type of services to be supported:
 Types of services supported include controlled term lookup in
 classification schemes and resolution of ids in identification
 systems.
 Concrete examples of these services include digital television
 services, (near) video on-demand services, and digital radio sound
 services. Another example is interactive multimedia applications
 which are tied to audiovisual content.
 This might, e.g., be a quiz show where viewers can compete against
 the contestants on the show by picking multiple-choice answers
 with their remote control. These end-user services are enabled by
 the metadata defined under the urn:dvb namespace.
 Another example is the web-portal site for the video-on-demand
 offering of an ISP. The portal pages are likely to describe the
 content in terms of title, genre, parental guidance, cast, etc.
 The ISP might either publish the DVB format description on their
 web-portal site directly, or develop an XSLT transformation to
 obtain an HTML incarnation of the data. In either case, a client
 device (in this example the home gateway or the ISP's web portal)
 will need to be able to resolve references to the urn:dvb
 namespace. Describing multimedia content in DVB format is a
 likely choice since it provides rich information specially
 tailored to multimedia applications like television, movies,
 music, etc. Furthermore, the DVB content descriptions for
 consumer terminals are, of course, compatible with the DVB
 Portable Content Format (PCF, defined in ETSI TS 102 523), which
 is used in content production environments so that propagation of
 content descriptions along the entire production chain is easily
 achieved.
5. Community Considerations
 With the digitization of the audiovisual broadcasting technologies,
 television receiver platforms have become quite similar to personal
 computer equipment in terms of performance, resources, and
 interfaces. Hence, cross-use of content from the respective other
 platform (i.e., TV and PC) becomes interesting to consumers and
 service providers alike. Web pages can for instance today be viewed
 on a general purpose computer, a set-top box, and a mobile phone just
 the same. Audio/video broadcasting services are arriving on mobile
 phones today ("mobile TV"), and efforts are clearly visible to bring
 such services to personal computer platforms as well ("IPTV").
 Hence, cross-linking between these two domains, the Internet/personal
 computer domain and the TV/broadcast domain is called for. Linking
 from broadcast domain metadata to Internet-based services is already
 enabled through the various URN and URI schemes established in the
 relevant DVB standards ([EN300468], [TS102323], and [TS102034]).
 Linking from Internet/web resources to DVB multimedia services is not
 yet possible in a well-defined way. Thus, a URN scheme is proposed
 for DVB defined metadata describing DVB services. As DVB issues its
 publications as international standards and has a well-defined
 compliance regime, this request is for a formal namespace.
 Open assignment and use of identifiers within the namespace:
 With on-going development of DVB standards, DVB will establish
 requirements for assignment and use of identifiers within the DVB
 namespace. Current identifier assignments can be inferred from
 the relevant DVB standards and from http://www.dvb.org/metadata.
 Considerations for resolution server software:
 With on-going development of DVB standards, DVB will establish
 requirements and seek candidates for operating resolution servers
 as appropriate.
 Sources for resolution information can either be stand-alone
 resolution services, which are announced as part of the Service
 Discovery and Selection (SD&S), or data conveyed as part of the
 SD&S information itself. To boot-strap the resolution process, a
 DVB client hence needs to discover an entry point (or set of) from
 which to obtain an initial Service Discovery and Selection XML
 record.
 By default, the actual service discovery information is provided
 on the IANA registered well-known port dvbservdsc (port number
 3937) via tcp and udp (see http://www.iana.org/assignments/port-
 numbers) on the IANA registered well-known multicast addresses
 224.0.23.14 (DvbServDisc on IPv4) and FF0X:0:0:0:0:0:0:12D
 (DvbServDisc on IPv6).
 As set forth in [TS102034], a list of non-default Service
 Discovery and Selection (SD&S) entry points addresses may also be
 provided via DNS based on the service location resource record
 (SRV RR) [RFC2782]. The service name for DVB services is
 "_dvbservdsc", the protocol may be tcp or udp, while the rest of
 the name is the domain name maintained by DVB for service
 discovery. This domain name is set to "services.dvb.org". The
 DVB organization will maintain the services.dvb.org domain name
 for service discovery, and new service providers should register
 with DVB to add them to the DNS SRV list.
 Considerations for resolution client software:
 With on-going development of DVB standards, DVB members will
 develop software implementations of its standards for various
 platforms. Today, these platforms typically include Open Source-
 based platforms such as Linux.
 To resolve a urn:dvb name, a client needs to retrieve Service
 Discovery and Selection (SD&S) data since this either directly
 contains resolution data, or lists stand-alone resolution services
 from which Resolution Authority Records (RAR) can be retrieved.
 To obtain the initial Service Discovery and Selection (SD&S) XML
 record, a client must by default first join the IANA registered
 well-known multicast addresses 224.0.23.14 (DvbServDisc on IPv4)
 and/or FF0X:0:0:0:0:0:0:12D (DvbServDisc on IPv6) and try to
 obtain a boot-strap record from the IANA registered well-known
 port dvbservdsc (port number 3937) via tcp and udp (see
 http://www.iana.org/assignments/port-numbers).
 To discover non-default entry points addresses, [TS102034] defines
 that a list of Service Discovery and Selection (SD&S) entry points
 addresses may be acquired via DNS according to the service
 location resource record (SRV RR) [RFC2782]. The service name is
 "_dvbservdsc"; the protocol may be tcp or udp, while the rest of
 the name is the domain name maintained by DVB for service
 discovery. This domain name is set to "services.dvb.org". So the
 lookup shall be either "_dvbservdsc._tcp.services.dvb.org" or
 "_dvbservdsc._udp.services.dvb.org". This requires that the
 terminal support an SRV cognizant DNS client and in a way
 according to the specification in [RFC2782]. The DVB organization
 will maintain the services.dvb.org domain name for service
 discovery. HTTP servers will be found via the tcp protocol method
 whilst the multicast addresses will be found via the udp protocol
 method.
6. Security Considerations
 There are no additional security considerations other than those
 normally associated with the use and resolution of URNs in general,
 which are described in [RFC1737], [RFC2141], and [RFC3406].
 This document registers a namespace for URNs. DVB may assign special
 meaning to certain of the characters of the Namespace Specific String
 in its specifications. Any security consideration resulting from
 such assignment is outside the scope of this document.
 When URNs are resolved, i.e., translated from names to locations, the
 way the locations are used or accessed may require the resources to
 be authenticated. The information about the authentication of either
 the name or the resource to which it refers should be carried by
 separate information passed along with the URN rather than in the URN
 itself. The design of such resolution mechanisms by DVB for DVB URNs
 is guided by [RFC2276] and such mechanisms will be published as DVB
 specifications.
7. IANA Considerations
 This document defines a URN NID registration of "dvb". IANA has
 registered "dvb" in the URN Namespaces registry.
8. References
 Note: The ETSI specifications listed below - as all ETSI standards -
 are available to the general public free of charge. They are
 accessible by going to http://www.etsi.org and visiting the
 standards download page. Select "Standards" from the
 navigation bar at the top, then choose "Download ETSI
 Standards" in the contents box on the left. A "Publications
 Download Area" link occurs at the top of the body text). The
 direct link to the downloads page is
 http://pda.etsi.org/pda/queryform.asp. When clicking on the
 download link on the search results page, an email address is
 requested for the PDF download. As being free-of-charge is
 funded by the European Commission, the email addresses are
 collected for statistical purposes only to demonstrate benefit
 to the general public.
 The ETSI specifications are normative references since the URNs
 are used to refer to, in conjunction with, and as part of
 commercial or public multimedia broadcast services. In most
 markets, these are under the control of a national regulator.
 So if a particular market chooses to use DVB services, in
 general, the regulator imposes compliance with the relevant DVB
 specifications to ensure interoperability and open competition
 in the marketplace. Some of the specifications also have "EN"
 status, which means that the European Commission has overridden
 any national regulations by mandating that if any commercial
 service is rolled out in Europe in the respective area, it must
 comply with the relevant DVB EN specification(s). Apart from
 those legal implications, DVB has become a brand to which
 consumers link certain expectations with regard to the level of
 service and interoperability. Of course, DVB wants to help
 manufacturers meeting those expectations by fostering
 interoperability.
8.1. Normative References
 [RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
 [RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
 "Uniform Resource Names (URN) Namespace Definition
 Mechanisms", BCP 66, RFC 3406, October 2002.
 [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
 specifying the location of services (DNS SRV)", RFC 2782,
 February 2000.
 [EN300468] European Telecommunications Standards Institute (ETSI),
 "Digital Video Broadcasting (DVB); Specification for
 Service Information (SI) in DVB systems", October 2007.
 [EN301192] European Telecommunications Standards Institute (ETSI),
 "Digital Video Broadcasting (DVB); DVB specification for
 data broadcasting", November 2004.
 [TS102323] European Telecommunications Standards Institute (ETSI),
 "Digital Video Broadcasting (DVB); Carriage and signalling
 of TV-Anytime information in DVB transport streams",
 November 2005.
 [TS102034] European Telecommunications Standards Institute (ETSI),
 "Digital Video Broadcasting (DVB); Transport of MPEG-2 TS
 Based DVB Services over IP Based Networks", October 2007.
8.2. Informative References
 [RFC1737] Sollins, K. and L. Masinter, "Functional Requirements for
 Uniform Resource Names", RFC 1737, December 1994.
 [RFC2276] Sollins, K., "Architectural Principles of Uniform Resource
 Name Resolution", RFC 2276, January 1998.
Authors' Addresses
 Alexander Adolf
 Micronas GmbH
 Frankenthalerstrasse 2
 D-81539 Munich
 GERMANY
 Tel: +49 89 54845 7203
 Fax: +49 89 54845 7900
 EMail: alexander.adolf@micronas.com
 Peter MacAvock
 DVB Digital Video Broadcasting
 Ancienne Route 17a
 CH-1218 Geneva
 SWITZERLAND
 Tel: +41 22 717 2717
 EMail: macavock@dvb.org
Full Copyright Statement
 Copyright (C) The IETF Trust (2008).
 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, THE IETF TRUST 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.