Internet DRAFT - draft-crocker-inreply-react
draft-crocker-inreply-react
Network Working Group D. Crocker
Internet-Draft Brandenburg InternetWorking
Intended status: Experimental R. Signes
Expires: October 18, 2021 Fastmail
N. Freed
Oracle
April 16, 2021
Reaction: Indicating Summary Reaction to a Message
draft-crocker-inreply-react-14
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. This specification permits a
similar facility for Internet Mail.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on October 18, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Crocker, et al. Expires October 18, 2021 [Page 1]
Internet-Draft reaction April 2021
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Reaction Content-Disposition . . . . . . . . . . . . . . . . 3
4. Reaction Message Processing . . . . . . . . . . . . . . . . . 5
5. Usability Considerations . . . . . . . . . . . . . . . . . . 6
5.1. Example Message . . . . . . . . . . . . . . . . . . . . . 6
5.2. Example Display . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Experimental Goals . . . . . . . . . . . . . . . . . . . . . 8
9. Normative References . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
The popularity of social media has led to user comfort with easily
signaling summary reactions to an author's posting, by using 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 extends this existing practice in social media and
instant messaging into 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 can be be treated as a
summary reaction to a previous message.
Crocker, et al. Expires October 18, 2021 [Page 2]
Internet-Draft reaction April 2021
2. Terminology
Unless provided here, terminology, architecture and specification
notation used in this document are incorporated from:
o [Mail-Arch]
o [Mail-Fmt]
o [MIME]
, and syntax is specified with
o [ABNF]
The ABNF rule Emoji-Seq is inherited from [Emoji-Seq]; details are in
Section 3.
Normative language, per [RFC8174]:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14 [RFC2119] [RFC8174] when, and only when, they
appear in all capitals, as shown here.
3. 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
Crocker, et al. Expires October 18, 2021 [Page 3]
Internet-Draft reaction April 2021
The content of this part is restricted to a single line of emoji.
The [ABNF] is:
part-content = emoji *(WSP 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 part-content is either the entire content portion of a message's
single MIME body or it is the content portion of the first MIME
multi-part body-part that constitute a message's body.
The ABNF rule emoji_sequence is inherited from [Emoji-Seq]. It
defines a set of Unicode code point sequences, which must then be
encoded as UTF-8. Each sequence forms a single pictograph. The BNF
syntax used in [Emoji-Seq] differs from [ABNF], and MUST be
interpreted as used in Unicode documentation. The referenced
document describes these as sequences of code points.
Note: The part-content can first be parsed into candidate
reactions, separated by WSP. Each candidate reaction that does
not constitute a single emoji-sequence (as per [Emoji-Seq]) is
invalid. Invalid candidates can be treated individually, rather
than affecting the remainder of the part-content's processing.
The remaining candidates form the set of reactions to be
processed. This approach assumes use of a mechanism for emoji
sequence validation that is not specified here.
The rule base-emojis is provided as a simple, common list, or
'vocabulary' of emojis, It was developed from some existing practice,
in social networking, and is intended for similar use. However
support for it as a base vocabulary is not required. Having
providers and consumers employ a common set will facilitate user
interoperability, but different sets of users might want to have
different, common (shared) sets.
The reaction emoji(s) are linked to the current message's In-Reply-
To: field, which references an earlier message, and provides a
Crocker, et al. Expires October 18, 2021 [Page 4]
Internet-Draft reaction April 2021
summary reaction to that earlier message. [Mail-Fmt]. For
processing details, see Section 4.
Reference to unallocated code points SHOULD NOT be treated as an
error; the corresponding UTF-8 encoded code points SHOULD be
processed using the system default method for denoting an unallocated
or undisplayable code point.
Note: The "emoji" token looks simple. It isn't. Implementers are
well-advised not to assume that emoji sequences are trivial to
parse or validate. Among other concerns, an implementation of the
Unicode Character Database is required. An emoji is more than a
stand-in for a simple alternation of characters. Similarly, one
emoji sequence is not interchangeable with, or equivalent to,
another one, and comparisons require detailed understanding of the
relevant Unicode mechanisms. Use of an existing Unicode
implementation will typically prove extremely helpful, as will an
understanding of the error modes that may arise with a chosen
implementation.
4. Reaction Message Processing
The presentation aspects of reaction processing are necessarily MUA-
specific and beyond the scope of this specification. In terms of the
message itself, a recipient MUA that supports this mechanism operates
as follows:
1. If a received message R's header contains an In-Reply-To: field,
check to see if it references a previous message that the MUA has
sent or received.
2. If R's In-Reply-To: does reference one, then check R's message
content for a part with a "reaction" Content-Disposition header
field, at either the outermost level or as part of a multipart at
the outermost level.
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 the part as a reaction.
Note: A message's content might include other, nested messages.
These can be analyzed for reactions, independently of the
containing message, applying the above algorithm for each
contained message, separately.
Again, the handling of a message that has been successfully processed
is MUA-specific and beyond the scope of this specification.
Crocker, et al. Expires October 18, 2021 [Page 5]
Internet-Draft reaction April 2021
5. 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. The handling of
multiple reactions, from the same person, is also an opportunity
for possibly interesting user experience design choice.
Culture: The use of an image, intended to serve as a semantic
signal, is determined and affected by cultural factors, which
differ in complexity and nuance. It is important to remain aware
that an author's intent when sending a particular emoji might not
match how the recipient interprets it. Even simple, commonly used
emojis can be be subject to these cultural differences.
5.1. Example Message
A simple message exchange might be:
To: recipient@example.com
From: author@example.com
Date: Today, 29 February 2021 00:00:00 -800
Message-id: 12345@example.com
Subject: Meeting
Can we chat at 1pm pacific, today?
with a thumbs-up, affirmative response of:
Crocker, et al. Expires October 18, 2021 [Page 6]
Internet-Draft reaction April 2021
To: author@example.com
From: recipient@example.org
Date: Today, 29 February 2021 00:00:10 -800
Message-id: 56789@example.org
In-Reply-To: 12345@example.com
Subject: Meeting
Mime-Version: 1.0 (1.0)
Content-Type: text/plain; charset=utf-8
Content-Disposition: Reaction
{U+1F44E}
The Unicode character, represented here as "{U+1F44E}" for
readability, would actually be sent as the UTF-8-encoded character.
The example could, of course, be more elaborate, such as the first of
a MIME multipart sequence.
5.2. Example Display
Repeating the caution that actual use of this capability requires
careful usability design and testing, this section describes simple
examples -- which have not been tested -- of how the reaction
response might be displayed in a summary list of messages :
Summary: Summary listings of messages in a folder include columns
such as Subject, From, and Date. Another might be added, to show
common reactions and a count of how many of them have been
received.
Message: A complete message is often displayed with a tailored
section for header-fields, enhancing the format and showing only
selected header fields. A pseudo-field might be added, for
reactions, again showing the symbol and a count.
6. Security Considerations
This specification employs message content that is a strict subset of
existing possible content, and thus introduces no new content-
specific security considerations. The fact that this content is
structured might seem to make it a new threat surface, but there is
no analysis demonstrating that it does.
This specification defines a distinct Content-Disposition value, for
specialized message content. Processing that handles the content
differently from other content in the message body might introduce
vulnerabilities. Since this capability is likely to produce new user
Crocker, et al. Expires October 18, 2021 [Page 7]
Internet-Draft reaction April 2021
interaction features, that might also produce new social engineering
vulnerabilities.
7. IANA Considerations
The IANA is requested to register the Reaction MIME Content-
Disposition parameter, per [RFC2183]
Content-Disposition parameter name: reaction
Allowable values for this parameter: (none)
Description: Permit a recipient to respond by signaling basic
reactions to an author's posting, such as with a 'thumbs up' or
'smiley' graphic
8. Experimental Goals
The basic, email-specific mechanics for this capability are well-
established and well-understood. Points of concern, therefore, are:
o Technical issues in using emojis within a message body part
o Market interest
o Usability
So the questions to answer for this Experimental specification are:
o Is there demonstrated interest by MUA developers?
o If MUA developers add this capability, is it used by authors?
o Does the presence of the Reaction capability create any
operational problems for recipients?
o Does the presence of the Reaction capability demonstrate
additional security issues?
o What specific changes to the specification are needed?
o What other comments will aid in use of this mechanism?
Please send comments to ietf-822@ietf.org.
Crocker, et al. Expires October 18, 2021 [Page 8]
Internet-Draft reaction April 2021
9. 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.
[RFC2183] Troost, R., Dorner, S., and K. Moore, Ed., "Communicating
Presentation Information in Internet Messages: The
Content-Disposition Header Field", RFC 2183,
DOI 10.17487/RFC2183, August 1997,
<https://www.rfc-editor.org/info/rfc2183>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Appendix A. Acknowledgements
This specification had substantive commentary on three IETF mailing
lists.
This work began as a private exercise, in July 2020, with private
discussion, for draft-crocker-reply-emoji. It morphed into draft-
crocker-inreply-react, with significant discussion on the ietf-822
mailing list, September through November 2020. The discussion
produced a fundamental change from proposing a new header field to
instead defining a new Content-Disposition type, as well as
significantly enhancing its text concerning Unicode. It also
produced two additional co-authors.
Crocker, et al. Expires October 18, 2021 [Page 9]
Internet-Draft reaction April 2021
In November 2020, the Dispatch list was queried about the draft, but
produced no discussion, though it did garner one statement of
interest.
A 4-week Last Call was issued on the document, January 2021,
resulting in quite a bit of fresh discussion on the last-call mailing
list, and producing further changes to the draft. After Last Call
completed, additional concerns were surfaced, about the Unicode-
related details, producing yet more changes to the draft. It also
produced a challenge that prompted the current version of the
Acknowledgements section.
Readers who are interested in the detail of the document's history
are encouraged to peruse the archives for the three lists, searching
Subject fields for "-react".
Authors' Addresses
Dave Crocker
Brandenburg InternetWorking
Email: dcrocker@bbiw.net
Ricardo Signes
Fastmail
Email: rjbs@semiotic.systems
Ned Freed
Oracle
Email: ned.freed@mrochek.com
Crocker, et al. Expires October 18, 2021 [Page 10]
