O. Levin Internet Draft RADVision Document: draft-levin-iptel-h323-url-scheme-00.txt> July 2000 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 [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. 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 proposal is to register the H.323 URL scheme, named "H323", within the IETF tree. It is despite the fact, that H.323 has been defined by ITU-T. H.323 has been widely deployed today and is used side-by-side with other Internet protocols and technologies. We would like to prevent 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 The H.323 URL is defined by H.323 [3] in ABNF exactly as shown below. It utilizes the Core Rules specified in section 6.1 of RFC-2234 [2]. As indicated in the syntax, the user string and the hostport string are both optional, though at least one shall be present. The H.323 URL is not case sensitive. H323-URL = "h323:" [ user ] [ "@" hostport ] user = unreserved / escaped 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 unreserved = alphanum / mark alphanum = ALPHA / DIGIT mark = "-" / "_" / "." / "!" / "~" / "*" / "'" / "(" / ")" / "&" / "=" / "+" / "$" / "," escaped = "%" HEXDIG HEXDIG 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 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 this section. 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 information about the location of the entity. The hostport, on the other hand, may specify the transport address of a Gatekeeper, a Gatekeeper Identifier, or the fully qualified domain name of the Gatekeeper, along with an optional port number for RAS communication. 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 feasible when the information about destination (or source) protocol support is known 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 9. Acknowledgments This document is posted on behalf of SG-16 ITU-T. The acknowledges go to this group of dedicated people. 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 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.323 "Packet-based multimedia communications systems", September 1999 4 ITU-T Recommendation H.225.0 "Call signalling protocols and media stream packetization for packet-based multimedia communication systems", September 1999 5 ITU-T Recommendation H.235 "Security and Encryption for H Series (H.323 and other H.245 based) multimedia terminals", January 1998 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 H.323 URL scheme definition July 2000 Levin Informational - Expiration January 2001 6 Levin Informational - Expiration January 2001 1