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Internet Draft                                                  A. Adolf
<draft-adolf-dvb-urn-05.txt>                               Micronas GmbH
Category: Informational                                      P. MacAvock
Expires December 2008                                        DVB Project
                                                           June 24, 2008

              A Uniform Resource Name (URN) Namespace for
              the Digital Video Broadcasting Project (DVB)
                      <draft-adolf-dvb-urn-05.txt>

Status of this Memo

   Distribution of this memo is unlimited.

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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.








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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 ......................................................9

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: 2007-02-28

   Declared registrant of the namespace:

      Name:           Peter MacAvock



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      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
      standardisation 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:




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      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 on-line 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 standardisation 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 defined by DVB and
   describing DVB multimedia and interactive services. Registration of
   urn:dvb as a formal namespace enables 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



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   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 which 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) which could be an IPTV set-
          top box, networked TV or personal digital recorder with an
          Ethernet or WLAN connection to a home gateway device.

      Further device classes will be addressed as DVB standardisation
      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].



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       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, 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



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      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 digitisation of the audiovisual broadcasting technologies,
   television receiver platforms 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.



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      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



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      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 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.

7.  IANA Considerations

   This document defines a URN NID registration of "dvb". IANA is
   requested to include it in the URN Namespaces registry.

8.  References

8.1.  Normative References

   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 bat at the top, then
   choose "Download ETSI Standards" in 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 the 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



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   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 bas become a brand to which
   consumers link certain expectations wrt. the level of service and
   interoperability. Of course DVB wants to help manufacturers meeting
   those expectations by fostering interoperability.

   [RFC2141]  Moats, R., "URN Syntax", RFC 2124, May 1997.

   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", October 2002.

   [RFC2782]  Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", 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















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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

































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