Internet DRAFT - draft-adolf-dvb-urn
draft-adolf-dvb-urn
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.
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
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.
Adolf Expires December 2008 FORMFEED[Page 1]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 2]
Internet Draft DVB URN June 24, 2008
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:
Adolf Expires December 2008 FORMFEED[Page 3]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 4]
Internet Draft DVB URN June 24, 2008
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].
Adolf Expires December 2008 FORMFEED[Page 5]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 6]
Internet Draft DVB URN June 24, 2008
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.
Adolf Expires December 2008 FORMFEED[Page 7]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 8]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 9]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 10]
Internet Draft DVB URN June 24, 2008
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
Adolf Expires December 2008 FORMFEED[Page 11]
Internet Draft DVB URN June 24, 2008
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.
Adolf Expires December 2008 FORMFEED[Page 12]
