Internet Engineering Task Force IPTEL WG Internet Draft Orit Levin draft-levin-iptel-h323-url-scheme-02.txt RADVision February, 2001 Expires: August, 2001 Category: Informational H.323 URL scheme definition Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not (automatically) granted. 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract H.323 Specification [3] and H.225.0 [4] together define a system and a set of protocols for multimedia communications services over Packet Based Networks (PBN). H.225.0 [4] messages define means for carrying any standard URL (Uniform Resource Locators) in order to specify source and destination, involved in the call. Starting from H.323v.4, H.323 URL is defined in order to specify H.323 party involved in the call. This H323-URL definition has a form of user@host where user corresponds to endpoint's alias and host corresponds to its domain/zone/gatekeeper (in terms of H.323 [3]). The purpose of this document is to register the specified (and presented below) H.323 URL scheme within IANA. This will allow for improved resources use and integration over the Internet. This document reproduces the exact H323-URL definition according to ITU-T Recommendation H.323v.4 [3]. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [1]. 3. URL scheme name Taking into consideration the guidelines of RFC-2717[12], the H.323 URL scheme, named "H323", is registered within the IETF tree. It is despite the fact, that H.323 has been defined by ITU-T. H.323 is widely deployed and is used side-by-side with other Internet protocols and technologies. This definition prevents the segmentation of URL scheme definitions, belonging to the same group of applications and running on the same Networks. 4. URL scheme formal syntax definition and character encoding This document reproduces the exact H323-URL definition according to ITU-T Recommendation H.323v.4 [3]. The H.323 URL is defined in ABNF as shown below. Note that it utilizes the Core Rules specified in section 6.1 of [2]. H323-URL = "h323:" address [ url-parameters ] address = user / "@" hostport / user "@" hostport user = %x21-x24 / %x26-x3F / %x41-7F / escaped ; The symbols "%", "@", and symbols with a ; character value below 0x21 may be represented ; as escaped sequences. hostport = host [ ":" port] host = hostname / IPv4address / IPv6reference hostname = *( domainlabel "." ) toplabel [ "." ] domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT IPv6reference = "[" IPv6address "]" IPV6address = hexpart [ ":" IPv4address ] hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ] hexseq = hex4 *( ":" hex4 ) hex4 = 1*4HEXDIG port = 1*DIGIT url-parameters = *( ";" url-parameter ) url-parameter = %x21-x24 / %x26-x3A / %x3C-x7F / escaped ; Specific parameter definitions are for further ; study. The symbols "%", ";", and symbols with ; a character value below 0x21 may be ; represented as escaped sequences. unreserved = alphanum / mark alphanum = ALPHA / DIGIT mark = "-" / "_" / "." / "!" / "~" / "*" / "'" / "(" / ")" / "&" / "=" / "+" / "$" / "," escaped = "%" HEXDIG HEXDIG The host is case insensitive. The user is a Unicode [15] string that shall be UTF-8 [14] encoded and then escaped as necessary. Except for characters with a numeric value below 0x80, the user is case sensitive. The characters with a numeric value below 0x80 are case insensitive. The character set and case sensitivity of the url-parameter is specified in each parameter definition. 5. Intended Usage One of the alias types defined by H.323 [3] is the url-ID, which is intended to contain standard URL schemes that may be used to reach resources. In addition, URLs are referenced within Annex K/H.323 [13] and may be used in other services added to H.323 in the future. An H.323 entity may accept any valid URL that it understands, but should support the H.323 URL as defined in [3] and is reproduced in this document. The H.323 URL is intended to help an entity resolve the address of another H.323 entity. It is composed of two parts: the user and the hostport. The user specifies an alias for the entity, such as a user or a service, without carrying any information about the location of the entity. The hostport, on the other hand, is the domain name of an Endpoint, Gatekeeper, or Border Element using terminology of [3]. 6. Applications and/or protocols, which may use this URL scheme name H.323 URL may be carried by another protocols, such as SIP [6]. It is practicable when the information about the destination (or the source) protocol is specified as a part of its URL. For example, that would facilitate SIP-H.323 interoperability (discussed in [7]) in more efficient manner. 7. Security Considerations H.323 URL definition conceptually has the same approach as already defined and widely used other URL schemes, such as [7]. When H.323 URL is carried within H.225.0 [4] messages the security is addressed by H.323 Security framework [5]. When H.323 URL is carried within other protocols (such as SIP [6]), the security is addressed within the corresponding protocol. 8. References 1 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 2 Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997 3 ITU-T Recommendation H.323v.4 "Packet-based multimedia communications systems", November 2000 4 ITU-T Recommendation H.225.0 "Call signalling protocols and media stream packetization for packet-based multimedia communication systems", November 2000 5 ITU-T Recommendation H.235 "Security and Encryption for H Series (H.323 and other H.245 based) multimedia terminals", November 2000 6 M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP: session initiation protocol," Request for Comments (Proposed Standard) 2543, Internet Engineering Task Force, Mar. 1999 7 K. Singh and H. Schulzrinne,"Interworking Between SIP/SDP and H.323" Internet Draft, May 2000 8 Berners-Lee, T., Masinter, L. and M. McCahill, "Uniform resource locators (URL)", RFC 1738, December 1994 9 Hoffman, P., Masinter, L. and J. Zawinski, "The mailto URL scheme", RFC 2368, July 1998 10 Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform resource identifiers (URI): generic syntax", RFC 2396, August 1998 11 Crocker, D., "Standard for the format of ARPA internet text messages", RFC STD 11, RFC 822, August 1982 12 R. Petke and I. King, "Registration Procedures for URL Scheme Names", RFC 2717, BCP-35, November 1999 13 ITU-T Recommendation H.323 Annex K "HTTP based service Control Transport Channel", May 2000 14 F. Yergeau, "UTF-8, a transformation format of ISO 10646", RFC 2279, January 1998 15 ISO/IEC 10646-1:1993, Information technology "Universal Multiple-Octet Coded Character Set (USC)" Part 1: Architecture and Basic Multilingual Plane 9. Acknowledgments This document is prepared and posted on behalf of SG-16 ITU-T. I wish to thank this group of dedicated people and especially Paul E. Jones and Robert Callaghan for their invaluable comments and active help. 10. Author's Addresses Orit Levin RADVision Inc., 575 Corporate Drive Suite 420 Mahwah, NJ 07430 Phone: +1 201 529 4300 Email: orit@radvision.com Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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. H.323 URL scheme definition February 2001 IETF Informational - Expiration August 2001