Internet Engineering Task Force Peter Parnes INTERNET-DRAFT CDT-LTU/Marratech AB draft-parnes-rtp-sdes-00.txt November 18, 1998 Expires: May, 1999 Proposal for additional RTP-SDES types Status of this Memo 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 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." To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Distribution of this document is unlimited. Abstract The Real-time Transfer Protocol, RTP (RFC1889 and currently under revision) includes basic support for conveying some predefined membership information types within a session using its control protocol (RTCP). This document describes a proposal for extending these membership types with additional membership information for user nickname, personal information web page reference, personal image reference and currently active media in session. Peter Parnes [Page 1] INTERNET-DRAFT RTP-SDES November 1998 1. Introduction The Real-time Transport Protocol, RTP [1] includes basic support for conveying some predefined membership information types within a session using its control protocol, RTCP. It currently supports distribution of information about a user's name, location, email, phone-number, temporary notes, tool name and private information. These different information types are distributed in so called source description RTCP packets, SDES packets. During the development of a number of RTP based applications it has been found that there is a need for further extending this list of supported information types with four additional SDES types namely: user nickname, personal information web page reference, personal image reference and currently active media. This document describes these additional SDES types. 2. The SDES Nickname Field Proposed SDES field name: Nickname Proposed SDES field number: 10 Includes a nickname of the presented user. Used by applications that require a shorter name like e.g. textual chat-tools or remote pointers in a distributed whiteboard. It have been argued that the user-name already conveyed in the SDES CNAME could be used but experience shows that this is not a very good option, as within many organizations users are not allowed to select their own user names. Example: Peppar 3. The SDES Homepage Field Proposed SDES field name: Homepage Proposed SDES field number: 11 Includes an URL to a web page of the presented user. Personal web pages are very common on the Internet today and most users have one. During live conferences it would be valuable if members of a session could get more information than propagated using existing SDES items about another member. It should be pointed out to application developers that this URL should NOT be automatically retrieved when a new member joins a Peter Parnes [Page 2] INTERNET-DRAFT RTP-SDES November 1998 session as that would create request "storm" at the corresponding web server. Instead, pages should only be retrieved based on direct user-action. If an automated process for retrieving member information is used then the application should wait a random time period before issuing the request for the web page. Example: http://www.cdt.luth.se/~peppar/ 4. The SDES Personal_image Field Proposed SDES field name: Personal_image Proposed SDES field number: 12 Includes an URL to an image of the corresponding user. The image should be encoded using the JPEG standard as that is supported by most platforms today. GIF is not recommended as that is a standard that requires licensing fees. PNG could be recommended in the future when it becomes more widely spread. The same retrieval considerations as for Homepage field above (see Sect. 3) should be considered here as well. Example: http://www.cdt.luth.se/~peppar/bilder/peppar.jpg 5. The SDES Active_media Field Proposed SDES field name: Active_media Proposed SDES field number: 13 Includes an informal textual representation of which other media a user currently has active in a session. This would allow user A to get information about which other media in a session user B is currently listening to without the need for user A to actually join the multicast group that corresponds to the other media. (It is taken for granted that different media are sent on different multicast groups as specified in RFC1889 to allow users to only receive the media they want.) Example of information sent to an audio RTP-group: video chat whiteboard 6. Final Notes and Conclusion For all the new SDES fields presented in this document the current format and syntax of SDES fields as presented in [1] should be Peter Parnes [Page 3] INTERNET-DRAFT RTP-SDES November 1998 reused. Also, no further changes to the timing considerations of [1] should not be done in respect to the changes presented in this document. These four additional RTCP SDES fields would allow application developers to create a richer membership interface to the user than before. It would also allow for better interaction between users in a session. 9. Author's Address Peter Parnes Centre for Distance-spanning Technology/Dept. of Computer Science Lulea University of Technology S-971 87 Lulea, Sweden Tel: +46 920 72421 Fax: +46 920 72191 E-Mail: peppar@cdt.luth.se WWW: 10. References [1] Schulzrinne/Casner/Frederic/Jacobson, "RTP: A Transport Protocol for Real-Time Applications", RFC 1889, January 1996 Peter Parnes [Page 4]