Network Working Group                                        J. Collins
Internet Draft                                          Nortel Networks
Document: <draft-ema-vpim-cb-01.txt>                         G. Parsons
Category: Informational                                 Nortel Networks
                                                      November 24, 2000


                    Voice Messaging Client Behaviour


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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Table of Contents


1. Abstract...........................................................2
2. Conventions used in this document..................................2
3. Introduction.......................................................2
4. Message Icon.......................................................3
 4.1 Proposed Mechanism ..............................................3
5. Sender's Number Column.............................................3
 5.1 Proposed Mechanism ..............................................3
6. Message Size.......................................................3
 6.1 Proposed Mechanism ..............................................4
7. Media Viewer.......................................................4
 7.1 Proposed Mechanism ..............................................5
8. Mark Message as Read...............................................5
 8.1 Proposed Mechanism ..............................................5
9. Security Considerations............................................5
10. References........................................................6
11. Acknowledgments...................................................6
12. Author's Addresses................................................6
13. Full Copyright Statement..........................................7


. Abstract

   This document defines the expected behaviour of a client to
   various aspects of a VPIM message or any voice or fax message.


. Conventions used in this document

   In examples, "C:" and "S:" indicate lines sent by the client and
   server respectively.

   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 [4].


. Introduction

   As Internet messaging evolves into Unified messaging, the term "e-
   mail" no longer refers to text-only messages.  Today's "e-mail" can
   also have voice and/or fax parts, as well as text.

   Each of voice, fax, and text have their own distinct characteristics,
   which are intuitive to the user.  For example, each of these message
   types require a different media viewer (text editor for text, audio
   player for voice, and image viewer for fax), and the dimensions of
   message size are also different for all three (kilobytes for text,
   seconds for voice, and pages for fax).

   How the messaging client responds to, and acts on these differences
   is termed "Client Behaviour".  This is dependant on the concept of
   "Message-Context" [2] (previously called primary content), which
   defines whether the message is a voice mail, fax, or text message.
   The client can utilize this header to determine the appropriate
   client behaviour for a particular message.

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. Message Icon

   The preferred method to distinguish between voice, fax, and text
   messages is with a visual cue, or icon.

   As it is possible for the message to contain more than one media
   type, the icon should describe the primary message content, as
   defined by the "Message-Context" header.  Obvious choices for the
   icon/message pairs would be a telephone for a voice message, a fax
   machine for a fax message, and an envelope for a text mail message.

   This could be taken a step further, and have the icon change to
   indicate that the message has been read (as is currently done in many
   email clients).  For example, a telephone with the receiver off-hook
   could indicate that the voice message has been played.  A fax
   machine with paper at the bottom, as opposed to the top, would show
   that the fax had been viewed.  Finally, as is currently the norm, an
   open envelope indicates that a text message has been read.

4.1 Proposed Mechanism

   As the choice of icon is determined by the primary message type, the
   client should obtain this information from the "Message-Context "
   message header.  This header is defined in [2].


. Sender's Number Column

   As is the case with most email clients today, important message
   information is organized into columns when presented to the user.
   Typical columns include the message subject, and the date the message
   was received.

   Another important piece of information for the user is the origin of
   the message.  For a voice or fax message, the origin is typically a
   telephone or fax machine respectively, each of which has an
   associated telephone number.  This telephone number is critical to
   the user if they wish to return the call.

5.1 Proposed Mechanism

   There is currently a proposal to add a new Internet message header
   to hold the originating telephone number [3].  If the message is
   indicated as being a voice or fax message per [2], the client should
   extract the number, and display it to the user in a separate column.
   As this header is defined to only hold the digits of the telephone
   number, it is left to the client to add any separating characters
   (e.g. "-").


. Message Size

   In the cases of large attachments, small clients and slow links there
   is also a need for the client to see the length of the message in a
   suitable format before opening it.


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   Currently, message size is normally given in kilobytes (kB).  This
   is sufficient for plain text messages, but it is not very useful in
   terms of voice and fax.  Instead, the size should give an indication
   of the length of the message, i.e. the duration (in seconds) of a
   voice message, and the number of pages of a fax.  Again, the message
   may contain multiple types, so the size displayed should be that of
   the primary content type, per [2].

6.1 Proposed Mechanisms

   There are three suggested methods to relay this information, of them,
   method 1 is favoured:

6.1.1  MIME Header Content-Duration as described in RFC2424 [5]

   For voice messages, the Content-Duration field of the main audio/*
   body part (as indicated by content-disposition per [1]) should be
   displayed as the length of the message.  If there are several audio
   parts, an implementation may display the message size as an aggregate
   of the length of each.

   For fax messages a new MIME Header, Content-Page-Length, would be
   defined, similar to Content-Duration with the exception that number
   of pages would be specified, rather than number of seconds. (e.g.
   Content-Page-Length:3).  This would be created at originator.


6.1.2  Message length indicated as a parameter of an existing Content
Header Field [7].

   This would be created at the source.  This method would allow the
   message length to be passed to the client by default in IMAP.  Again
   the client would have to chose between the main voice message length
   or an aggregate message length for display.

   Content-Type Header Field example:

        Content-Type=audio/*; length=50
        Content-Type=image/tiff; pages=3


6.1.3  Message length indicated as part of an existing RFC822 Header
Field [10].

   This field would be created at the source and may include message
   length information, but because it is part of the message headers, it
   could also be amended on reception (by a local process).  This method
   would allow the message length to be passed to any client by default
   and not require any client modification.  If used, this field would
   indicate the aggregate length of all attachments.

   Subject Header Field example:

        Subject=Voice Message (0:04)
        Subject=Fax Message (3p)


. Media Viewer

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   When a message is initially opened, the client should, by default,
   open the proper media viewer to display the primary message content,
   i.e. an audio player for voice messages, image viewer for fax, and
   text editor for text messages.

   Where there is more than one body part, obviously the appropriate
   viewer should be used depending on which body part the user has
   selected.

   In the case where several viewers are available for a single media
   type, the user should be prompted to select the desired viewer on
   the first occasion that the message type is encountered.  That
   viewer should then become the default viewer for that media type.

   The user should have the ability to change the default viewer for a
   media type at any time.

7.1 Proposed Mechanism

   As mentioned, the default viewer displayed to the user should be the
   appropriate one for the primary message type.  The client is able to
   determine the primary message type from the "Message-Context"
   message header per [2].


. Mark Message as Read

   Obviously, the user must be able to know which messages they have
   read, and which are unread.  This feature would also control the
   message icon as mentioned in section 1.

   With the proliferation of voice and fax messages, clients should only
   indicate that these messages are read when the primary body part has
   been read. The default is currently to mark a message read, when the
   first body part (typically text) is viewed.

8.1 Proposed Mechanism

   Implementation of this feature on most clients is a local issue.

   IMAP4 [6] clients should only set \SEEN flag after the first
   attachment of the primary content type has been opened.
   For example, if the message context is voice message  , the \SEEN
   flag would be set after the primary voice message (indicated by
   content-disposition [1] or content-criticality [8]) is opened.


. Security Considerations

   The desirable client behaviours described here are intended to
   provide the user with a better desktop experience.  However, it is
   open to the same risks as any mail client.  That is, the client is
   not responsible for the format of the message received, it only
   interprets.  As a result, messages could be spoofed or masqueraded
   to look like a message they are not to elicit a desired client
   behaviour.  This could be used to fool the end user, for example,


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   into thinking a message was a voice message (because of the icon)
   when it was not.


. References

   1. Parsons, G., Vaudreuil, G., "Voice Profile for Internet Mail -
   version 2", draft-ietf-vpim-vpimv2r2-01.txt, November 2000, Work in
   Progress.

   2. Burger, E., Candell, E., Klyne, G., Eliot, C., "Message Context
   for Internet Mail", draft-ietf-vpim-hint-01.txt, November 2000, Work
   in Progress

   3. Collins, J., "Calling Line Identification for VPIM Messages",
   draft-ema-vpim-clid-01.txt, November 2000, Work in Progress

   4. Bradner, S., "Key words for use in RFCs to Indicate Requirement
   Levels", BCP 14, RFC 2119, March 1997

   5. Vaudreuil, G., Parsons, G., "Content Duration MIME Header
   Definition", RFC2424, September 1998

   6. Crispin, M., "Internet Message Access Protocol - Version 4rev1",
   RFC 2060, December 1996

   7. Freed, N., Borenstein, N., "Multipurpose Internet Mail Extensions
   (MIME) Part One: Format of Internet Message Bodies", RFC 2045,
   November 1996

   8. Burger, E., Candell, E., "Critical Content of Internet
   Mail" <draft-ietf-vpim-cc-02.txt>, November 2000, Work in Progress.

   9. Schulzrinne, H., Rao, A., Lanphier, R., "Real Time Streaming
   Protocol (RTSP)", RFC 2326, April 1998

   10. Resnick, P., "Internet Message Format",
   <draft-ietf-drums-msg-fmt-09.txt>, Work in Progress.


. Acknowledgments

   The authors would like to acknowledge all those who contributed to
   IMAP and client discussions in the VPIM Working Group.


. Author's Addresses

   Jason Collins
   Nortel Networks
   P.O. Box 3511, Station C
   Ottawa, ON
   K1Y 4H7

   Phone:+1-613-768-4087
   Fax: +1-613-763-4461
   Email:jcolli1@nortelnetworks.com


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   Glenn Parsons
   Nortel Networks
   P.O. Box 3511, Station C
   Ottawa, ON
   K1Y 4H7

   Phone: +1-613-763-7582
   Fax: +1-416-597-7005
   Email: gparsons@nortelnetworks.com


. Full Copyright Statement

   Copyright (C) The Internet Society (2000).  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 implementation 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.





















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