Network Working Group D. Zigmond
Request for Comments: 2838 WebTV Networks, Inc.
Category: Informational M. Vickers
Liberate Technologies, Inc.
May 2000
Network Working Group D. Zigmond
Request for Comments: 2838 WebTV Networks, Inc.
Category: Informational M. Vickers
Liberate Technologies, Inc.
May 2000
Uniform Resource Identifiers for Television Broadcasts
电视广播的统一资源标识符
Status of this Memo
本备忘录的状况
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2000). All Rights Reserved.
版权所有（C）互联网协会（2000年）。版权所有。
World-Wide Web browsers are starting to appear on a variety of consumer electronic devices, such as television sets and television set-top boxes, which are capable of receiving television programming from either terrestrial broadcast, satellite broadcast, or cable. In this context there is a need to reference television broadcasts using the URI format described in [RFC 2396]. This document describes a widely-implemented URI scheme to refer to such broadcasts.
万维网浏览器开始出现在各种消费电子设备上，如电视机和电视机顶盒，它们能够从地面广播、卫星广播或有线电视接收电视节目。在这种情况下，需要使用[RFC 2396]中描述的URI格式参考电视广播。本文档描述了一个广泛实现的URI方案，用于引用此类广播。
The basic structure of a television URI is:
电视URI的基本结构是：
tv:<broadcast>
tv:<broadcast>
where broadcast is a description of the data source. The description takes the form of a DNS-style identifier for a particular broadcaster or television network. For example:
其中，广播是对数据源的描述。描述采用特定广播公司或电视网络的DNS样式标识符的形式。例如：
tv:wqed.org the WQED station tv:nbc.com the NBC network
电视：wqed.org wqed电台电视：nbc.com nbc网络
A simplest form of the "tv:" URI scheme is used to refer to the "current" or "default" channel:
“tv:”URI方案的最简单形式用于引用“当前”或“默认”频道：
tv:
电视：
This URI refers to whichever television broadcast is currently being received by the device. It is often used in combination with HTML content that is actually being broadcast along with the audio and video, where the meaning of "current broadcast" is quite unambiguous (because it is the broadcast along with which the content containing the URI was received). This is in fact the most common usage of the "tv:" scheme today, and is explicitly referenced by the recently published specification of the Advanced Television Enhancement Forum [ATVEF 1.1].
此URI指设备当前正在接收的任何电视广播。它通常与实际随音频和视频一起广播的HTML内容结合使用，其中“当前广播”的含义非常明确（因为它是随包含URI的内容一起接收的广播）。这实际上是当今“tv:”方案最常见的用法，最近发布的高级电视增强论坛规范[ATVEF 1.1]明确提到了这一点。
Television broadcasts traditionally have been identified in a variety of ways. All terrestrial television broadcasters are assigned call signs (such as "KDKA" or "WQED") to identify their signal. These are generally assigned by national authorities (such as the Federal Communications Commission in the United States) and are world unique. The global namespace is managed by the International Telecommunications Union, which assigns portions to member countries (see [ITU RR]).
传统上，电视广播以多种方式被识别。所有地面电视广播公司都分配了呼号（如“KDKA”或“WQED”）以识别其信号。它们通常由国家当局（如美国联邦通信委员会）指定，是世界上独一无二的。全球名称空间由国际电信联盟（International Telecommunications Union）管理，该联盟将部分内容分配给成员国（参见[ITU RR]）。
Many modern television networks are not broadcasted over-the-air, but available only through cable or satellite subscriptions. The identifiers for these networks (such as the familiar "CNN" and "HBO") are not regulated at this time. In some countries, even over-the-air broadcasters use these sorts of identifiers, rather than call signs.
许多现代电视网络不是通过空中广播，而是只能通过有线或卫星订阅。这些网络的标识符（如熟悉的“CNN”和“HBO”）目前不受监管。在一些国家，甚至空中广播公司也使用这些标识，而不是呼号。
Unfortunately, these two namespaces overlap, with most network identifiers also being valid call signs. Furthermore, network identifiers are not world unique, and many cases exist of name collisions. (For example, both the Australian Broadcast Corporation and the American Broadcasting Company identify themselves as "ABC".) In order to ensure uniqueness, the "tv:" scheme uses DNS-style identifiers for all broadcast streams. Because these build on the existing registration system for DNS hostname, all name collisions can be resolved through the existing DNS dispute resolution processes.
不幸的是，这两个名称空间重叠，大多数网络标识符也是有效的呼号。此外，网络标识符不是世界唯一的，并且存在许多名称冲突的情况。（例如，澳大利亚广播公司和美国广播公司都将自己标识为“ABC”。）为了确保唯一性，“tv:”方案对所有广播流使用DNS样式的标识符。因为这些建立在现有的DNS主机名注册系统上，所以所有名称冲突都可以通过现有的DNS争议解决过程来解决。
In the simplest form, domain names themselves are used as broadcast identifiers. For example:
在最简单的形式中，域名本身被用作广播标识符。例如：
tv:abc.com the American Broadcast Company tv:abc.co.au the Australian Broadcast Corporation
电视：abc.com美国广播公司电视：abc.co.au澳大利亚广播公司
In some cases, networks have multiple broadcast streams that need to be distinguished. This is also handled in DNS style:
在某些情况下，网络具有需要区分的多个广播流。这也是以DNS方式处理的：
tv:east.hbo.com HBO East tv:west.hbo.com HBO West
电视：east.hbo.com hbo east电视：west.hbo.com hbo west
It is important to note that these DNS-style identifiers need not match real hostnames; they should not be resolved to IP addresses using DNS. Thus, using the terms as defined in RFC 2396, the "tv:" scheme is a Uniform Resource Identifier and not a Uniform Resource Locator.
需要注意的是，这些DNS样式标识符不需要与真实主机名匹配；不应使用DNS将它们解析为IP地址。因此，使用RFC 2396中定义的术语，“tv:”方案是统一的资源标识符，而不是统一的资源定位器。
In order to support these identifiers in a "tv:" URI, a receiver must implement a means to map known identifiers to frequencies. The nature of this map and the way in which it is used are currently browser-and device-specific and are beyond the scope of this document. In this way, the "tv:" scheme is somewhat analogous to the "news:" and "file:" schemes in [1]: it merely names a television broadcast signal but assumes that the local browser has some means for actually retrieving that signal on the local device. A variety of software systems currently provide device-specific mappings from such identifiers to specific channel numbers or directly to frequencies. These systems can be incorporated into television sets or set-top boxes to facilitate the interpretation of television URIs by the client device.
为了在“tv:”URI中支持这些标识符，接收器必须实现将已知标识符映射到频率的方法。此地图的性质及其使用方式目前是特定于浏览器和设备的，超出了本文档的范围。这样，“tv:”方案在某种程度上类似于[1]中的“news:”和“file:”方案：它仅命名一个电视广播信号，但假设本地浏览器有一些在本地设备上实际检索该信号的方法。目前，各种软件系统提供从此类标识符到特定信道号或直接到频率的设备特定映射。这些系统可以集成到电视机或机顶盒中，以便于客户端设备对电视uri进行解释。
Previous drafts of this specification allowed broadcasts to be identified by channel numbers, such as "tv:4", and this form is currently supported by several independent platforms. The channel numbers generally correspond to tuning frequencies in the various national broadcast frequency standards; for example, "tv:4" in the United states would be found at 66 MHz. However, because this mapping of channel numbers to frequencies varies from country to country, this form is particularly ill-suited to use on the Internet.
本规范以前的草案允许通过频道号来识别广播，如“tv:4”，目前有几个独立的平台支持这种形式。频道编号通常对应于各种国家广播频率标准中的调谐频率；例如，美国的“tv:4”频率为66 MHz。然而，由于频道号码到频率的映射因国家而异，因此这种形式特别不适合在互联网上使用。
Previous drafts also allowed network identifiers and call signs to be used directly as broadcast identifiers, as in "tv:abc" and "tv:kron". These forms should not be used because of the name collision issues described in the previous section.
以前的草案还允许网络标识符和呼号直接用作广播标识符，如“tv:abc”和“tv:kron”。由于上一节中描述的名称冲突问题，不应使用这些表单。
The following is a formal specification for the new URIs:
以下是新URI的正式规范：
tvuri = "tv:" [ broadcast ]
broadcast = dns-identifier
dns-identifier = *( domainlabel "." ) toplabel [ "." ]
domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
toplabel = alpha | alpha *( alphanum | "-" ) alphanum
tvuri = "tv:" [ broadcast ]
broadcast = dns-identifier
dns-identifier = *( domainlabel "." ) toplabel [ "." ]
domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
toplabel = alpha | alpha *( alphanum | "-" ) alphanum
The definitions of alpha and alphanum are from [RFC 2396]. Furthermore, the definition of dns-identifier is identical to the definition of hostname in RFC 2396, and is case-insensitive.
alpha和alphanum的定义来自[RFC 2396]。此外，dns标识符的定义与RFC 2396中主机名的定义相同，并且不区分大小写。
Many of the ideas in this document came out of conversations with Andrew Lochart. Other people who supplied valuable input include Matt Trifiro and Eric Del Sesto. The original draft of this URI scheme was developed while the author was at Wink Communications. More recent suggestions have come from Lee Acton, Jonathan Boltax, Dean Blackketter, Michael Dolan, Iain Hackett, Jim Helman, Sean McDowell, David Mott, Scott Watson, and others in the ATVEF Technical Working Group (which the authors co-chaired), and from Craig Finseth, Gomer Thomas, Harald Alvestrand, and Larry Masinter.
本文件中的许多想法来自与安德鲁·洛哈特的对话。其他提供宝贵意见的人包括马特·特里菲罗和埃里克·德尔·塞斯托。此URI方案的原始草案是在作者在Wink Communications时开发的。最近的建议来自于李·阿克顿、乔纳森·博尔塔克斯、迪安·布莱克特、迈克尔·多兰、伊恩·哈克特、吉姆·赫尔曼、肖恩·麦克道尔、大卫·莫特、斯科特·沃森和ATVEF技术工作组（作者共同主持）的其他人，以及克雷格·芬塞思、戈默·托马斯、哈拉尔德·阿尔维斯特兰和拉里·马斯特。
This new URI scheme is subject to the same security implications as the general URI scheme described in [RFC 2396]. It is possible that the mere act of viewing a television broadcast signal may cause costs to be incurred to the viewer in some instances (e.g., "pay-per-view" movies and events). Any software that uses this URI scheme to allow automatic tuning of a client device to a particular television broadcast signal should alert users before performing actions that may incur costs to the user.
这个新的URI方案与[RFC 2396]中描述的通用URI方案具有相同的安全含义。在某些情况下，仅仅观看电视广播信号的行为可能会导致观众产生成本（例如，“按次付费”电影和事件）。任何使用此URI方案允许将客户端设备自动调谐到特定电视广播信号的软件都应在执行可能会给用户带来成本的操作之前提醒用户。
[RFC 2396] Berners T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[RFC 2396]Berners T.，Fielding，R.和L.Masinter，“统一资源标识符（URI）：通用语法”，RFC 2396，1998年8月。
[ATVEF 1.1] Advanced Television Enhancement Forum, "Advanced Television Enhancement Forum Specification Version 1.1r26," February 1999. http://www.atvef.com/library/spec1_1a.html
[ATVEF 1.1]高级电视增强论坛，“高级电视增强论坛规范版本1.1r26”，1999年2月。http://www.atvef.com/library/spec1_1a.html
[ITU RR] International Telecommunications Union, "Radio Regulations," 1998. See especially Article S19, "Identification of stations," and Appendix S42, "Table of allocation of international call sign series."
[ITU RR]国际电信联盟，“无线电条例”，1998年。特别参见第S19条“车站标识”和附录S42“国际呼号系列分配表”
Dan Zigmond WebTV Networks, Inc. 1065 La Avenida Mountain View, CA 94043 USA
Dan Zigmond WebTV Networks，Inc.美国加利福尼亚州拉维尼达山景大道1065号，邮编94043
EMail: djz@corp.webtv.net
EMail: djz@corp.webtv.net
Mark Vickers Liberate Technologies 2 Circle Star Way San Carlos, CA 94070 USA
美国加利福尼亚州圣卡洛斯市马克·维克斯解放技术2号环星路，邮编94070
EMail: mav@liberate.com
EMail: mav@liberate.com
Copyright (C) The Internet Society (2000). All Rights Reserved.
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确认
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