Network Working Group D. Crocker
Internet-Draft Brandenburg InternetWorking
Intended status: Informational R. Signes
Expires: April 25, 2021 Fastmail
N. Freed
Oracle
October 22, 2020
React: Indicating Summary Reaction to a Message
draft-crocker-inreply-react-03
Abstract
The popularity of social media has led to user comfort with easily
signaling basic reactions to an author's posting, such as with a
'thumbs up' or 'smiley' graphic indication. This specification
permits a similar facility for Internet Mail.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Reaction Content-Disposition . . . . . . . . . . . . . . . . 3
3. Usability Considerations . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The popularity of social media has led to user comfort with easily
signaling summary reactions to an author's posting, by marking basic
emoji graphics, such as with a 'thumbs up', 'heart', or 'smiley'
indication. Sometimes the permitted repertoire is constrained to a
small set and sometimes a more extensive range of indicators is
supported.
This specification defines a similar facility for Internet Mail.
While it is already possible to include symbols and graphics as part
of an email reply's content, there has not been an established means
of signalling the semantic substance that such data are to be taken
as a summary 'reaction' to the original message. That is, a
mechanism to identify symbols as specifically providing a summary
reaction to the cited message, rather than merely being part of the
free text in the body of a response. Such a structured use of the
symbol(s) allows recipient MUAs to correlate this reaction to the
original message and possibly to display the information
distinctively.
This facility defines a new MIME Content-Disposition, to be used in
conjunction with the In-Reply-To header field, to specify that a part
of a message containing one or more emojis be treated as a summary
reaction to a previous message.
Unless provided here, terminology, architecture and specification
used in this document are incorporated from [Mail-Arch], [Mail-Fmt],
[MIME], and [ABNF]. The ABNF rule Emoji-Seq is inherited from
[Emoji-Seq].
Discussion of this specification should take place on the ietf-
822@ietf.org mailing list.
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2. Reaction Content-Disposition
A message sent as a reply MAY include a part containing:
Content-Disposition: Reaction
If such a field is specified the content-type of the part MUST be:
Content-Type: text/plain; charset=utf-8
The content of this part is restricted to single line of emoji. The
[ABNF] is:
part-content = emoji *(lwsp emoji) CRLF
emoji = emoji_sequence
emoji_sequence = { defined in [Emoji-Seq] }
base-emojis = thumbs-up / thumbs-down / grinning-face / frowning-face / crying-face
thumbs-up = {U+1F44D}
thumbs-down = {U+1F44E}
grinning-face = {U+1F600}
frowning-face = {U+2639}
crying-face = {U+1F622}
The rule emoji_sequence is inherited from [Emoji-Seq]. It permits
one or more bytes to form a single presentation image.
The emoji(s) express a recipient's summary reaction to the specific
message referenced by the accompanying In-Reply-To header field.
[Mail-Fmt].
Reference to unallocated code points SHOULD NOT be treated as an
error; associated bytes SHOULD be processed using the system default
method for denoting an unallocated or undisplayable code point.
The presentation aspects of reaction processing are necessarily MUA-
specific and beyond the scope of this specification. In terms of the
message itself, recipient MUAs that support this mechanism operate as
follows:
1. If an In-Reply-To field is present check to see if it references
a previous message the MUA has received.
2. If a reference to an existing message is found check for a part
with a "reaction" content-disposition at either the outermost
level or as part of a multipart at the outermost level.
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3. If such a part is found, and the content of the part conforms to
the restrictions outlined above, remove the part from the message
and process it as a reaction.
4. Processing terminates if no parts remain in the message. If
parts remain process the remaining message content as a reply.
Again, the handling of a message that has been successfully processed
is MUA-specific and beyond the scope of this specification.
3. Usability Considerations
This specification defines a mechanism for the structuring and
carriage of information. It does not define any user-level details
of use. However the design of the user-level mechanisms associated
with this facility is paramount. This section discusses some issues
to consider.
Creation: Because an email environment is different from a typical
social media platform, there are significant -- and potentially
challenging -- choices in the design of the user interface, to
support indication of a reaction. Is the reaction to be sent only
to the original author, or should it be sent to all recipients?
Should the reaction always be sent in a discrete message
containing only the reaction, or should the user also be able to
include other message content? (Note that carriage of the
reaction in a normal email message enables inclusion of this other
content.)
Display: Reaction indications might be more useful when displayed in
close visual proximity to the original message, rather than merely
as part of an email response thread.
4. Security Considerations
This specification employs message content that is a strict subset of
existing content, and thus introduces no new content-specific
security considerations.
This specification defines a distinct label for specialized message
content. Processing that handles the content differently from other
content in the message body might introduce vulnerabilities.
5. IANA Considerations
New Content-Disposition Parameter Registrations
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This document specifies a new "reaction" content disposition and its
handling that should be added to the IANA registry.
6. Normative References
[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008.
[Emoji-Seq]
Davis, M., Ed. and P. Edberg., Ed., "Unicode(R) Technical
Standard #51: Unicode Emoji", WEB
http://www.unicode.org/reports/tr51/#def_emoji_sequence,
September 2020.
[Mail-Arch]
Crocker, D., "Internet Mail Architecture", RFC 5598, July
2009.
[Mail-Fmt]
Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008.
[MIME] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
Appendix A. Acknowledgements
This specification has been discussed in the ietf-822 mailing list.
Active commentary and suggestions were offered by: Nathaniel
Borenstein, Richard Clayton, Ned Freed, Bron Gondwana, Valdis
Klētnieks, John Levine, Brandon Long, Keith Moore, Pete Resnick,
Michael Richardson, Alessandro Vesely
Authors' Addresses
Dave Crocker
Brandenburg InternetWorking
Email: dcrocker@bbiw.net
Ricardo Signes
Fastmail
Email: rjbs@semiotic.systems
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Ned Freed
Oracle
Email: ned.freed@mrochek.com
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