1.\"
  2.\" Copyright (c) 2019 Ted Unangst
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 16.Dd $Mdocdate$
 17.Dt ACTIVITYPUB 7
 18.Os
 19.Sh NAME
 20.Nm activitypub
 21.Nd notes about the honk implementation
 22.Sh DESCRIPTION
 23The
 24.Xr honk 1
 25utility processes status updates and other microblog activities using the
 26.Nm ActivityPub
 27protocol to exchange messages with other servers.
 28The specification is subject to interpretation, and not all implementations
 29behave in the same way.
 30This document attempts to clarify honk's behavior.
 31It is not intended to be a complete description of
 32.Nm ActivityPub ,
 33but may be useful as a guide to other implementors looking to interoperate.
 34.Ss OBJECTS
 35The following object or document types are supported.
 36.Bl -tag -width tenletters
 37.It Vt Note
 38Fully supported.
 39The default object type for honk.
 40.It Vt Article
 41Fully supported.
 42.It Vt Page
 43Supported.
 44.It Vt Question
 45Read only support.
 46Appears similar to a Note.
 47.It Vt Event
 48Supported.
 49Appears similar to a Note.
 50Can be both created and received, but
 51.Vt Invite
 52activities are ignored.
 53.It Vt Video
 54Limited support.
 55.It Vt Audio
 56Limited Support.
 57.El
 58.Pp
 59Honk primarily supports HTML content, not markdown or other formats,
 60with a wide range of permitted HTML tags in object
 61.Fa content
 62fields.
 63The following tags are supported.
 64.Bd -literal -offset indent
 65a, img, span,
 66div, h1, h2, h3, h4, h5, h6, hr,
 67table, thead, tbody, tfoot, th, tr, td, colgroup, col,
 68p, br, pre, code, blockquote, q,
 69caption, kbd, time, wbr, aside,
 70ruby, rtc, rb, rt, details, summary,
 71samp, mark, ins, dfn, cite, abbr, address,
 72strong, em, b, i, s, u, sub, sup, del, tt, small,
 73ol, ul, li, dl, dt, dd
 74.Ed
 75.Pp
 76The following tag attributes are permitted.
 77.Bd -literal -offset indent
 78href, src, alt, colspan, rowspan
 79.Ed
 80.Pp
 81The following class names are used for syntax highlighting code blocks.
 82.Bd -literal -offset indent
 83kw, bi, st, nm, tp, op, cm, al, dl
 84.Ed
 85.Ss ACTIVITIES
 86The following activities are supported.
 87.Bl -tag -width tenletters
 88.It Vt Create
 89Fully supported.
 90.It Vt Announce
 91Supported with share semantics.
 92.It Vt Read
 93Supported.
 94Primarily used to acknowledge replies and complete threads.
 95Can be interpreted to mean reply is approved, if not endorsed.
 96.It Vt Add
 97Works with collections.
 98.It Vt Follow
 99Supported.
100Can follow both actors and collections.
101.Vt Accept
102and
103.Vt Undo
104require that the original request be quoted, not referred to by URI.
105.It Vt Update
106Supported.
107Honk sends and receives
108.Vt Update
109activities.
110.It Vt Delete
111Does what it can.
112.It Vt Like
113Don't be ridiculous.
114.El
115.Ss METADATA
116The following additional object types are supported, typically as
117.Fa tag
118or
119.Fa attachment .
120.Bl -tag -width tenletters
121.It Mention
122Pretty @ machine.
123.It Emoji
124Inline text :emoji: with image replacement.
125.It Place
126Included as a
127.Fa location .
128Supports
129.Fa name ,
130.Fa url ,
131.Fa latitude ,
132and
133.Fa longitude .
134.It Document
135Plain text and images in jpeg, gif, png, and webp formats are supported.
136Other formats are linked to origin.
137.El
138.Pp
139The
140.Fa replies
141array will be populated with a list of acknowledged replies.
142.Ss EXTENSIONS
143Honk also supports a
144.Vt Ping
145activity and will respond with a
146.Vt Pong
147activity.
148This is useful for debugging networking connectivity issues without
149visible side effects.
150See ping.txt for details.
151.Ss SECURITY
152Honk uses http signatures.
153.Ss WEBFINGER
154Honk implements the
155.Vt webfinger
156end point and will use it for @mention resolution.
157It is not required for federation.
158.Ss LD-JSON
159Not really.
160.Sh SEE ALSO
161.Xr intro 1 ,
162.Xr honk 1
163.Sh STANDARDS
164.Pp
165.Lk https://www.w3.org/TR/activitypub/ "ActivityPub"
166.Pp
167.Lk https://www.w3.org/TR/activitystreams-vocabulary/ "Activity Vocabulary"
168.Sh CAVEATS
169The ActivityPub standard is subject to interpretation, and not all
170implementations are as enlightened as honk.