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, th, tr, td, colgroup, col,
 68p, br, pre, code, blockquote, q,
 69samp, mark, ins, dfn, cite, abbr, address,
 70strong, em, b, i, s, u, sub, sup, del, tt, small,
 71ol, ul, li, dl, dt, dd
 72.Ed
 73.Pp
 74The following tag attributes are permitted.
 75.Bd -literal -offset indent
 76href, src, alt, colspan, rowspan
 77.Ed
 78.Pp
 79The following class names are used for syntax highlighting code blocks.
 80.Bd -literal -offset indent
 81kw, bi, st, nm, tp, op, cm, al, dl
 82.Ed
 83.Ss ACTIVITIES
 84The following activities are supported.
 85.Bl -tag -width tenletters
 86.It Vt Create
 87Fully supported.
 88.It Vt Announce
 89Supported with share semantics.
 90.It Vt Read
 91Supported.
 92Primarily used to acknowledge replies and complete threads.
 93Can be interpreted to mean reply is approved, if not endorsed.
 94.It Vt Add
 95Works with collections.
 96.It Vt Follow
 97Supported.
 98Can follow both actors and collections.
 99.Vt Accept
100and
101.Vt Undo
102require that the original request be quoted, not referred to by URI.
103.It Vt Update
104Supported.
105Honk sends and receives
106.Vt Update
107activities.
108.It Vt Delete
109Does what it can.
110.It Vt Like
111Don't be ridiculous.
112.El
113.Ss METADATA
114The following additional object types are supported, typically as
115.Fa tag
116or
117.Fa attachment .
118.Bl -tag -width tenletters
119.It Mention
120Pretty @ machine.
121.It Emoji
122Inline text :emoji: with image replacement.
123.It Place
124Included as a
125.Fa location .
126Supports
127.Fa name ,
128.Fa url ,
129.Fa latitude ,
130and
131.Fa longitude .
132.It Document
133Plain text and images in jpeg, gif, png, and webp formats are supported.
134Other formats are linked to origin.
135.El
136.Pp
137The
138.Fa replies
139array will be populated with a list of acknowledged replies.
140.Ss EXTENSIONS
141Honk also supports a
142.Vt Ping
143activity and will respond with a
144.Vt Pong
145activity.
146This is useful for debugging networking connectivity issues without
147visible side effects.
148See ping.txt for details.
149.Ss SECURITY
150Honk uses http signatures.
151.Ss WEBFINGER
152Honk implements the
153.Vt webfinger
154end point and will use it for @mention resolution.
155It is not required for federation.
156.Ss LD-JSON
157Not really.
158.Sh SEE ALSO
159.Xr intro 1 ,
160.Xr honk 1
161.Sh STANDARDS
162.Pp
163.Lk https://www.w3.org/TR/activitypub/ "ActivityPub"
164.Pp
165.Lk https://www.w3.org/TR/activitystreams-vocabulary/ "Activity Vocabulary"
166.Sh CAVEATS
167The ActivityPub standard is subject to interpretation, and not all
168implementations are as enlightened as honk.