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< article >
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< h1 > Fediverse ID Syntax< / h1 >
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< section >
< address class = "h-card" >
by
< a rel = "author" class = "u-url" href = "http://changelog.ca/" > < span class = "p-given-name" > Charles< / span > < span class = "p-additional-name" > Iliya< / span > < span class = "p-family-name" > Krempeaux< / span > < / a >
< / address >
< / section >
< section >
< p >
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Currently there is no canonical syntax for a < strong > Fediverse ID< / strong > .
However, we can infer a syntax for the < strong > Fediverse ID< / strong > given that it has to be used with < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > .
< / p >
< / section >
< section >
< h2 > De Facto < / h2 >
< p >
Currently, the syntax of a < strong > Fediverse ID< / strong > is whatever each < ziba-link dir = ".." name = "software" > Fediverse software< / ziba-link > supports.
Which could be different from each other!
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And could even change over time!
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< / p >
< p >
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The final say for what is and is not a valid < strong > Fediverse ID< / strong > are the many implementations of < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > in-the-wild for all the different < ziba-link dir = ".." name = "software" > Fediverse software< / ziba-link > out there.
Which again could be different from each other!
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And again could even change over time!
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< / p >
< p >
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The reason being because, from a technical point-of-view, a < strong > Fediverse ID< / strong > is turned into an < ziba-link dir = ".." transform = "lowerslugcase" > acct URI< / ziba-link > and then resolved with < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > .
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< / p >
< p >
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But, having said that, we can infer a < em > minimum syntax< / em > and a < em > maximum syntax< / em > for what should be considered a valid < strong > Fediverse ID< / strong > .
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I.e., the syntax that any implmentation for < strong > Fediverse ID< / strong > s < em > should< / em > support.
But, to say it explicitly, an implemention for < strong > Fediverse ID< / strong > s < em > could< / em > support more than just what is given by thes syntaxes.
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< / p >
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< p >
Perhaps oddly, the < strong > maximal syntax< / strong > is simpler than the < strong > minimal syntax< / strong > .
< / p >
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< / section >
< section >
< h2 > Maximal Fediverse ID Syntax< / h2 >
< p >
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An < ziba-link dir = ".." transform = "lowerslugcase" > acct URI< / ziba-link > has some constraints according to the IETF RFC-7565 (The 'acct' URI Scheme) specification.
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But — software, such as < ziba-link dir = ".." name = "software" > Fediverse software< / ziba-link > , don't have to implement those constraints.
I.e., they can accept more than just what IETF RFC-7565 (The 'acct' URI Scheme) specifies.
< / p >
< p >
Given that, here is a more < em > maximal< / em > syntax for a < strong > Fediverse ID< / strong > :
< / p >
< pre >
fediverseID = "@" [ actor ] "@" host
< / pre >
< p >
Where, given that ‘ ’ < em > not at-sign< / em > ) is any Unicode character that isn't the U+0040 ("@") at-signs —
< / p >
< p >
‘ ’
< / p >
< pre >
actor = NOTATSIGN *NOTATSIGN ; one or more characters that are not an at-sign ("@") (U+0040)
< / pre >
< p >
And ‘ ’
< / p >
< pre >
host = NOTATSIGN *NOTATSIGN ; one or more characters that are not an at-sign ("@") (U+0040)
< / pre >
< p >
Note in this < em > maximal< / em > < strong > Fediverse ID< / strong > syntax ‘ ’
But when ‘ ’
< / p >
< p >
Here are some < strong > Fediverse ID< / strong > s that fit this < em > maximal< / em > < strong > Fediverse ID< / strong > syntax:
< / p >
< ul >
< li > < code class = "fediverseid" > @joeblow@example.com< / code > < / li >
< li > < code class = "fediverseid" > @janedoe@something.example< / code > < / li >
< li > < code class = "fediverseid" > @reiver@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @reiver@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @dariush@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @malekeh@changelog.ca< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @دورود@example.com< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @@example.com< / code > < / li >
< li > < code class = "fediverseid" > @@something.example< / code > < / li >
< li > < code class = "fediverseid" > @@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @@changelog.ca< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @🙂@example.com< / code > < / li >
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< li > < code class = "fediverseid" > @hello world :-)@something.example< / code > < / li >
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< li > < code class = "fediverseid" > @(╯°□°)╯︵ ┻━┻@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @😈❤️@greatape.social< / code > < / li >
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< li > < code class = "fediverseid" > @✪@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @awesome 🙂@changelog.ca< / code > < / li >
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< / ul >
< ul >
< li > < code class = "fediverseid" > @.@example.com< / code > < / li >
< li > < code class = "fediverseid" > @joe.blow@example.com< / code > < / li >
< li > < code class = "fediverseid" > @jane.doe@something.example< / code > < / li >
< li > < code class = "fediverseid" > @.reiver@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @reiver.@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @d.a.r.i.u.sh@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @.m.a.l.e.k.e.h.@changelog.ca< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @joeblow+@example.com< / code > < / li >
< li > < code class = "fediverseid" > @janedoe+@something.example< / code > < / li >
< li > < code class = "fediverseid" > @reiver+@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @reiver+@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @dariush+@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @malekeh+@changelog.ca< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @joeblow+tech@example.com< / code > < / li >
< li > < code class = "fediverseid" > @janedoe+psychology@something.example< / code > < / li >
< li > < code class = "fediverseid" > @reiver+fediverse@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @reiver+allyourbases@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @dariush+one@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @malekeh+two@changelog.ca< / code > < / li >
< / ul >
< ul >
< li > < code class = "fediverseid" > @joeblow/tech@example.com< / code > < / li >
< li > < code class = "fediverseid" > @janedoe/psychology@something.example< / code > < / li >
< li > < code class = "fediverseid" > @reiver/fediverse@mastodon.social< / code > < / li >
< li > < code class = "fediverseid" > @reiver/allyourbases@greatape.social< / code > < / li >
< li > < code class = "fediverseid" > @dariush/one@changelog.ca< / code > < / li >
< li > < code class = "fediverseid" > @malekeh/two@changelog.ca< / code > < / li >
< / ul >
< / section >
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< section >
< h2 > acct URI< / h2 >
< p >
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Part of the process of < strong > resolving< / strong > a < strong > Fediverse ID< / strong > transfomrs a < strong > Fediverse ID< / strong > into an < ziba-link dir = ".." transform = "lowercase" > acct URI< / ziba-link > .
(And then using that < ziba-link dir = ".." transform = "lowercase" > acct URI< / ziba-link > version of the < strong > Fediverse ID< / strong > makes a request to < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > .)
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< / p >
< p >
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Here is an example of transforming a < strong > Fediverse ID< / strong > into an < ziba-link dir = ".." transform = "lowercase" > acct URI< / ziba-link > :
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< / p >
< pre >
at sign
↓
@joeblow@example.com ← Fediverse ID
acct:joeblow@example.com ← acct URI
↑
no at sign
< / pre >
< p >
A client would then make a request to:
< / p >
< pre >
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https://example.com/.well-known/host-meta
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< / pre >
< p >
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To discover what the (template) URL for < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > is.
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And then, for example, if it is at:
< / p >
< pre >
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https://example.com/.well-known/webfinger?resource={uri}
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< / pre >
< p >
Then make a request to:
< / p >
< pre >
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https://example.com/.well-known/webfinger?resource=acct:joeblow@example.com
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< / pre >
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< p >
This < ziba-link dir = ".." transform = "lowercase" > WebFinger< / ziba-link > implementation < em > could< / em > accept whatever it wants.
It doesn't have to restrict itself to what is specified by the IETF RFC-7565 (The 'acct' URI Scheme) specification.
BUT —
< / p >
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< / section >
< section >
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< h2 > Minimal Fediverse ID Syntax< / h2 >
< p >
Let us consider what a < em > minimal< / em > < strong > Fediverse ID< / strong > syntax would be if we constrained ourselves to what the IETF RFC-7565 (The 'acct' URI Scheme) specificaiton says.
< / p >
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< p >
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Here is what we get:
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< / p >
< pre >
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fediverseID = "@" actor "@" host
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< / pre >
< p >
Where “actor” is defined as:
< / p >
< pre >
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actor = unreserved / sub-delims 0*( unreserved / pct-encoded / sub-delims )
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
sub-delims = "!" / "$" / "& " / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
pct-encoded = "%" HEXDIG HEXDIG
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39 ; 0-9
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
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< / pre >
< p >
(Again note that an implementation < em > could< / em > support more characters for “actor” than what is given by this definition.)
< / p >
< p >
And “host” is defined as
< / p >
< pre >
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host = IP-literal / IPv4address / reg-name
IP-literal = "[" ( IPv6address / IPvFuture ) "]"
IPv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32
/ [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
/ [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
/ [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32
/ [ *4( h16 ":" ) h16 ] "::" ls32
/ [ *5( h16 ":" ) h16 ] "::" h16
/ [ *6( h16 ":" ) h16 ] "::"
h16 = 1*4HEXDIG
ls32 = ( h16 ":" h16 ) / IPv4address
IPvFuture = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255
reg-name = *( unreserved / pct-encoded / sub-delims )
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< / pre >
< / section >
< / article >
