Network Working Group D. Zigmond Internet-Draft Wink Communications draft-zigmond-media-url-00.txt October 1996 Expire in six months Uniform Resource Locators for Television and Telephony 1. Status of this Document This document is an Internet-Draft. 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 working documents valid for a maximum of six months. Internet-Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet-Drafts as reference material or to cite them other than as a "working draft" or "work in progress." To learn the current status of any Internet-Draft, please check the 1id-abstracts.txt listing contained in the Internet-Drafts Shadow Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or munnari.oz.au. Distribution of this document is unlimited. Please send comments to dan.zigmond@wink.com. 2. Introduction World-Wide Web browsers are starting to appear on a variety of consumer electronic devices, such as televisions and both cellular and wireline telephones. On these devices, some of the URL schemes described in [1] are inappropriate. For example, many of these devices lack local storage, so the "file" scheme is of little use. However, these devices usually have access to other sources of information, such as television broadcasts and voice telephone services. This draft proposes three new URL schemes for accessing such information on appropriate devices. 3. Television Tuning URL The basic structure of a television URL is: tv:// where channel is an alpha-numeric description of the channel or network to be tuned. This can be either a channel number, or a standard broadcaster identifier. For example: tv://nbc tune to the NBC network tv://wqed tune to the WQED station tv://12 tune to channel 12 Note that for a browser to understand non-numeric channel identifiers, it will require a local channel map for the device. The nature of this map and the way in which it is used will be browser- and device-specific and is beyond the scope of this draft. In this way, the "tv" scheme is somewhat analagous to the "news" and "file" schemes in [1], in that 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. 4. Telephone Dialing URL The basic structure of a telephone URL is: phone://[+-] where where both country-code and telephone-number are numeric strings. The phone-number may contain one or more hyphens ("-"); the country-code cannot. The effect of "fetching" a telephone URL is for the device to dial the given phone number. For example: phone://+1-510-337-6359 dial a number in North America phone://800-943-9465 dial a number in the local country The first form (with country-code) is strongly recommended since it is the only form that can be unambiguously parsed internationally. The device processing the phone URL is responsible for converting the URL into the actual string of digits that needs to be dialed, potentially adding digits particular to the local phone system or removing digits not required to place the call from a given location. The way in which this is done will be browser- and device-specific and is beyond the scope of this draft. Unlike the "tv" scheme above (but like "fax" below), "phone" does not designate a data object to be directly accessed. In this way, it is analogous to the "mailto" scheme in [1]. 5. Facsimile Transmission URL A fax URL describes a phone number to which facsimile transmissions can be sent. It has a form very similar to the "phone" scheme above: fax://[+-] where the country-code and phone-number follow the same rules as for "phone" URLs. For example: fax://+1-510-337-2960 send a fax in North America Like "phone" above, the "fax" scheme is closely related to the "mailto" scheme in [1], in that it it does not represent a data object to be accessed directly. 6. BNF for Television and Telephone URLs The following is a formal specification for the new URLs: tvurl = "tv://" channel phoneurl = "phone://" ["+" country-code "-"] phone-number faxurl = "fax://" ["+" country-code "-"] phone-number channel = *[ alpha | digit ] country-code = * digit phone-number = digit *[ digit | "-" ] The following definitions are from RFC 1738. Between the Internet Draft version and RFC 1738 two relevant changes were made: '=' was moved from the character class to , and was removed from the alternatives in . Neither nor is referred to in this document nor in RFC 1738. lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z" hialpha = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z" alpha = lowalpha | hialpha digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" safe = "$" | "-" | "_" | "." | "+" extra = "!" | "*" | "'" | "(" | ")" | "," national = "{" | "}" | "|" | "\" | "^^" | "~" | "[" | "]" | "`" punctuation = "<" | ">" | "#" | "%" | <"> reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" hex = digit | "A" | "B" | "C" | "D" | "E" | "F" | "a" | "b" | "c" | "d" | "e" | "f" escape = "%" hex hex unreserved = alpha | digit | safe | extra uchar = unreserved | escape xchar = unreserved | reserved | escape digits = 1*digit 7. Acknowledgments 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. 8. Security Considerations The two new URL schemes are subject to the same security implications as the general URL scheme [1], so the usual precautions apply. This means, for example, that a locator might no longer point to the object that was originally intended. It also means that it may be possible to construct a URL so that an attempt to perform a harmless idempotent operation such as the retrieval of an object will in fact cause a possibly damaging remote operation to occur. The telephone dialing URL, in particular, may cause an unwanted telephone call to be placed, possibly resulted in additional telephone charges to the user. 9. References [1] Berners-Lee, T., Masinter, L., McCahill, M. (editors), "Uniform Resource Locators (URL)", RFC 1738, December 1994. ftp://ds.internic.net/rfc/rfc1738.txt 10. Author's Address Dan Zigmond Wink Communications 1001 Marina Village Parkway Alameda CA 94501 Email: dan.zigmond@wink.com Voice: +1-510-337-6359 Fax: +1-510-337-2960