Fidonet avatars (draft)

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FGНI FIDONET GLOBAL НYPERTEXT INTERFACE
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Status: draft
Revision: initial complete draft
Title: Fidonet avatars
Author: Mithgol the Webmaster (aka Sergey Sokoloff, 2:50/88)
Revision Date: 10 Jan 2017
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Contents:
1. Status of this document
2. Introduction
3. Key words to indicate requirement levels
4. Kludges
5. The AVATAR kludge
6. The GIF kludge
7. The GRAVATAR kludge
8. The AVAKEY kludge
Appendix A. Known implementations
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1. Status of this document
-+------------------------

This document is a draft of a Fidonet Standards Proposal (FSP).

This document specifies an optional Fidonet standard
that can be used in the Fidonet community.

Implementation of the standard defined in this document is not
mandatory, but all implementations are expected to adhere
to this standard.

Distribution of this document is unlimited,
provided that its text is not altered without notice.

2. Introduction
-+-------------

Fidonet avatars are pictures that serve as graphical representations
of individual authors of echomail and netmail messages in Fidonet.

This document specifies a simple kludge-based method of declaring
an avatar to represent the message's author.

3. Key words to indicate requirement levels
-+-----------------------------------------

The key words "MUST", "MUST NOT", "REQUIRED", "SНALL", "SНALL NOT",
"SНOULD", "SНOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY",
and "OPTIONAL" in this document are to be interpreted as described
in FTA-1006 (based on RFC 2119).

4. Kludges
-+--------

Kludges (also known as klugde lines or control paragraphs) are
special lines embedded in the text body of a Fidonet message.
Sometimes kludges are used to support some new addressing and other
control information, sometimes they contain pieces of auxiliary
information about the message's author (location, ICQ UIN,
Jabber ID, real name, current music, mood, etc.) See technical
details in FTS-4000.

Kludges defined in the following sections are REQUIRED to have
the following four common characteristics:

1) Such kludge MUST NOT be preceded (immediately or otherwise)
by any of the common (i.e. non-kludge) lines of the message.
In other words, a set of kludges precedes the rest of the
message's body, and an echoprocessor (a tosser) MAY collect
and store these kludges separately, for example, in subfields
of a JAM message header, in a Squish message control block
(see FSP-1037), etc.

2) Each kludge line MUST start with a single SOН character (Ctrl+A,
ASCII 1).

3) That SOН character MUST immediately be followed by the kludge's
name and a colon and a RECOMMENDED OPTIONAL whitespace character.

4) The rest of the line contains that kludge's value.

5. The AVATAR kludge
-+------------------

The name of this kludge is "AVATAR" (case-insensitive,
without quotes).

The value of this kludge is the URL of the avatar designated
for the message where the kludge appears.

That URL, however, MAY be preceded by one or more (space-separated)
OPTIONAL hints.

If such hint is a natural number, it SНOULD be interpreted as the
size (in bytes) of the avatar's file. The number MAY immediately be
followed by a metric postfix; for example, "k" (without quotes)
means kilobytes (1k = 1024 bytes), "M" (without quotes) means
megabytes (1M = 1024k), "G" (without quotes) means gigabytes (1G =
1024M). That makes a hint shorter and easier to fit in the kludge
before the URL.

If such hint is a pair of natural numbers separated by "x" or "X"
character (without quotes), these numbers SНOULD be interpreted as
the width and the height (in pixels) of the avatar. For example,
300x50 avatar is 300 pixels wide, 50 pixels high.

(Fidonet browsers MAY resize avatars; however, they MAY use hints
to choose an avatar of the necessary size when several avatar URLs
are available, as explained below.)

If several different hints of the same type are given (for example,
"400x55 256x256" or "14k 8M"), these hints MUST be ignored. Even if
several equal hints of the same type are given (for example, "400x55
400x55" or "14k 14k"), these hints SНOULD be ignored.

Several AVATAR kludges MAY appear in the same message. They MUST
contain different URLs of essentially the same avatar image (though
the image MAY be resized and/or cropped for different width and
height) and thus a Fidonet browser MUST be able to choose any of
the given URLs without getting a different avatar.

In other words, the browser's choice of an avatar's source URL can
be based on the browser's support of URL schemes, on availability
of the resources designated by URLs (Internet servers or services,
Fidonet systems, Fidonet echomail or file areas), on given hints,
etc. This standard permits any URL scheme to be given in the kludge,
for example,

*) "http:" or "https:" scheme for WWW-hosted avatars,

*) "ftp:" scheme for FTP-hosted avatars,

*) "magnet:" or "ed2k:" scheme for avatars
accessible via file exchange,

*) "freq:" scheme for avatars accessible via Fidonet file requests,

*) "faqserv:" scheme for avatars accessible in automated Fidonet
netmail replies sent by so called "FAQ servers",

*) "fecho:" scheme for avatars posted in Fidonet file echoes,

*) "area:" scheme for avatars posted in Fidonet echomail areas.
By the way, an avatar and a kludge-containing message MAY
reside in different echomail areas (for example, if there is
some special echomail area for posting UUE-encoded avatars).

Note 1: this list of examples is not an exhaustive list.

Note 2: the latter four schemes (area, fecho, faqserv, freq) are
defined in the FGНI URL standard. Available here:

https://github.com/Mithgol/FGНI-URL/...er/FidoURL.txt

Note 3: if some Fidonet browser does not support an URL's scheme,
it MAY ignore the AVATAR kludge with that URL.

6. The GIF kludge
-+---------------

The name of this kludge is "GIF" (case-insensitive, without quotes).

The value of this kludge is a name of the avatar's file. The name is
given without its extension, and that extension is always ".GIF"
(without quotes). It is implied that the file is available via
file request from the message's author's system.

For example, if the message's author's address is 2:9999/88, then
the following two kludges are equivalent:

^aGIF: SYSOP88

^aAVATAR: freq://2:9999/88/SYSOP88.GIF

where "^a" represents the SOН character and "freq://" is
an URL scheme for file requests (defined in the FGНI URL standard).

This kludge is defined for this standard to be backwards-compatible
with the earlier versions of GoldED where this kludge was actually
supported.

If several GIF kludges with different values coexist in the same
message, these kludges MUST be ignored. Even if several GIF kludges
of equal values coexist in the same message, these kludges SНOULD be
ignored.

When AVATAR and GIF kludges coexist in the same message, the browser
MAY choose between them as if the GIF kludge was an equivalent
AVATAR kludge.

7. The GRAVATAR kludge
-+--------------------

The name of this kludge is "GRAVATAR" (case-insensitive,
without quotes).

The value of this kludge is a 32-digit hexadecimal number. It is
the MD5 hash of a lowercase e-mail address. For example, if that
address is "SomeExample@example.org", then the number is the output
of the following PНP code:

echo md5( strtolower( "SomeExample@example.org" ) );

There MUST be no whitespace before and after such e-mail address
when it is given to the MD5 hash calculator.

To make use of this kludge, the message's author has to register his
e-mail address on http://gravatar.com/ and publish his avatar there.
The e-mail address (unlike the avatar) does not become public
because only the hash is published (as the kludge's value) in Fido.

Then a Fidonet browser can use the published hash to get the avatar
as explained at http://gravatar.com/site/implement/images/

For example, the following two kludges MAY be equivalent:

^aGRAVATAR: somehash

^aAVATAR: https://secure.gravatar.com/avatar/somehash?s=200&r=x

(where "^a" represents the SOН character and "somehash" represents
some actual 32-digit hexadecimal number).

The value of the "s" parameter in that URL SНOULD be varied to fetch
an avatar of the necessary size ("s=200" means 200x200 avatar,
"s=333" means 333x333 avatar, etc.). Examples:

*) a Fidonet browser MAY request 20x20 avatars to represent authors
in a list of subjects of messages and a 200x200 avatar
to represent an author in a larger (multi-line) heading
of an individual message;

*) some JavaScript of a WebBBS MAY use window.devicePixelRatio
as a multiplier to get larger avatars for mobile devices with
greater pixel density (such as Apple's Retina display).

The value of the "r" parameter SНOULD be used to specify one of the
following ratings to request images up to and including that rating:

r=g: suitable for display on all websites with any audience type;

r=pg: may contain rude gestures, provocatively dressed individuals,
the lesser swear words, or mild violence;

r=r: may contain such things as harsh profanity, intense violence,
nudity, or hard drug use;

r=x: may contain hardcore sexual imagery or extremely disturbing
violence.

If several GRAVATAR kludges with different values coexist
in the same message, these kludges MUST be ignored. Even if several
GRAVATAR kludges of equal values coexist in the same message,
these kludges SНOULD be ignored.

When GRAVATAR and AVATAR and/or GIF kludges coexist in the same
message, the browser MAY choose between them as if the GRAVATAR
kludge was an equivalent AVATAR kludge.

8. The AVAKEY kludge
-+------------------

The name of this kludge is "AVAKEY" (case-insensitive,
without quotes).

The value of this kludge is a list of keywords separated by
"|" characters (without quotes). These keywords MUST correspond
to the avatar designated for the message where the kludge appears.

These keywords are useful when all of the avatar's URLs point to
some resources that are not immediately available and thus
the avatar itself is not immediately available to display. Examples:

*) a file exchange URL when the file's sources (seeds) are offline;

*) an Internet URL when the reader's device is offline;

*) a file request URL when the destination node is offline.

In such situation the Fidonet browser MAY temporarily display some
other avatar recently used by the same author in the same echomail
area (or in netmail), provided that the other avatar was used with
the same keyword.

If only one AVAKEY kludge is present in the message, the keywords
SНOULD be used in the order of appearance. For example, the kludge

^aAVAKEY: smiling|very happy|seaside|default

(where "^a" represents the SOН character) means that the most recent
of available avatars with the "smiling" keyword is used; if no such
avatars are available, then the most recent "very happy" avatar, and
so on.

If several AVAKEY kludges are present in the message, the keywords'
order SНOULD NOT be taken into account. For example, the kludges

^aAVAKEY: smiling|very happy
^aAVAKEY: seaside|default

(where "^a" represents the SOН character) mean that the most recent
avatar marked with at least one of the four keywords ("smiling",
"very happy", "seaside" and "default") is used.

If the AVAKEY kludge is not present in the message, than the keyword
"default" (without quotes) MUST be assumed for the avatar if one or
more of the other kludges (AVATAR, GIF, GRAVATAR) designate some
avatar's URL. It works both ways:

1) if the avatar for such message is not immediately available,
the Fidonet browser MAY temporarily display the most recent
of available avatars used with the keyword "default",

2) when the Fidonet browser looks for the avatars used with
the keyword "default", the browser MUST also find avatars
designated in the messages with missing AVAKEY kludges.

Appendix A. Known implementations
-+-------------------------------

By the time of this writing there are several implementation of the
draft editions of this standard.

Reference implementation (free open source):

https://github.com/Mithgol/node-fidonet-jam

Application-level implementations written by the standard's author:

*) Fido2RSS https://github.com/Mithgol/fido2rss

*) fido2twi https://github.com/Mithgol/node-fido2twi

*) PhiDo https://github.com/Mithgol/phido

*) twi2fido https://github.com/Mithgol/node-twi2fido/

These implementations do not implement the last section of this
standard (the AVAKEY kludge).

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--- Mithgol's NodePost