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]
