Axismundi Object Projections

Axismundi Object Projections turns a WordPress object — a post, an attachment, an
archive, a folder — or an Axismundi Actor into an ActivityStreams 2.0 object or
collection, so that the URL it already has can answer with JSON-LD when something asks
for it.

It owns representation and nothing else: a transformer registry, the URIs objects and
collections are named by, and the single renderer that writes the JSON. What a thing is
stays with the plugin that stores it; this decides how it is described to a reader that
speaks ActivityStreams.

This plugin needs Axismundi Actors. It resolves the identities an object names — its
author, the accounts it mentions, the Actor documents it serves — and without that registry
there is nobody for any of them to refer to.

Axismundi Activities is optional, and adds four things. Without it a published post is
public and is projected as such, which is this plugin’s own default. With it, the four
authored visibility levels decide who a post is addressed to, an Actor’s outbox and follow
collections have contents rather than being empty, an object states who may quote it, and an
object says who published it. Nothing here breaks when it is absent; less is said.

That last one is worth stating plainly: who an object is attributed to is decided by whatever
recorded its publication, not derived here from the WordPress author. An object nobody has
published has no attributedTo — it is readable, it simply was not published by anyone.

What this version does

• Content negotiation on the URL a post already has. Ask for
  application/activity+json and the same address answers with JSON-LD instead of HTML.
• A Core Post to Article transformer, and an optional adapter for Axismundi Media
  Library attachments.
• A post’s own media, listed as attachments so a reader can fetch what the body shows:
  the featured image and the media blocks the author placed. Only media this site holds —
  a hotlinked image is left in the text, because its type and size cannot be stated.
• Collections: an Actor’s outbox, followers and following, a shared media folder at a
  stable UUID route, and a replies collection. An Actor document always names them; without
  an Activity ledger they answer empty rather than 404.
• The relations that make a document readable in context — hashtags, mentions, thread
  edges, reply context, and quote context — kept as their own records rather than parsed
  out of content each time.
• A remote object repository: URI-keyed, rebuildable observations of objects this site
  has been told about, for administrators to inspect under Tools > Remote Objects.
• An administrator can probe a remote collection and its first page without storing the
  collection, following its item URLs, or downloading anything binary.

What this version does not do

There is no Activity ledger, no inbox write handling, no Follow/Like/Announce state, no
HTTP signatures, and no delivery. Those belong to Axismundi Activities and to the
ActivityPub transport boundary. Nothing here signs or sends an Activity.

Alongside the official ActivityPub plugin

Both plugins negotiate the same canonical URLs, and two answers for one address is worse
than either answer alone. So when the official ActivityPub plugin is active, this plugin’s
standalone negotiator turns itself off and leaves those URLs to it, while the registry
and renderer stay available. Nothing here overrides or replaces that plugin’s object ids.

What is stored about other people’s documents

An observation of a remote object is a cache, not a record: it is keyed by the remote
URI, which stays canonical, and it can be rebuilt by fetching again. Observations expire,
and a scheduled daily task deletes the expired ones along with anything left pointing at
them.

Remote media is never downloaded and never hotlinked. A cached object’s attachments are
described — type, size, the text the author wrote about them — and not fetched. Where a
cached object is shown locally at all, it is shown noindex, only for objects that were
addressed publicly, and only as a courtesy view beside the remote original.

External services

This plugin reads documents from other websites. Every request is a GET made through
wp_safe_remote_get(): redirects are not followed automatically, the response size is
capped, and any address inside your own network is refused. Nothing about your site’s
content or your users is sent as data. As with any outgoing HTTP request the server being
contacted receives your site’s IP address, and a User-Agent header naming this
plugin, its version, and your site’s home URL.

Requests happen for two reasons, and the second is worth being clear about.

Because an administrator asked.

• Fetching one remote object. Under Tools > Remote Objects, an administrator can
  fetch the address of an ActivityStreams object to inspect it. What is read is that one
  JSON document; what is stored is its metadata — tags, mentions, audience, attachment
  descriptors, extension properties, and the payload itself, escaped.
• Probing a remote collection. An administrator can read a collection and its first
  page from the same host to see what it contains. The collection is not stored, its item
  URLs are not followed, and nothing binary is downloaded.

Because something arrived here naming an address.

• Only if you switch it on. Under Tools > Remote Objects there is a setting called
  Background acquisition, and it is off unless an administrator turns it on. While it
  is off this site contacts a remote server only when you ask it to on that screen.
• With it on: when a publicly addressed Announce reaches this site’s inbox carrying only
  the URI of the object it announces, that one address is queued for a single background
  fetch, so that the announcement can be shown as something rather than as a link. The
  object’s author is looked up the same way if this site does not already know them.
• Either way the request tells the remote host that this site exists, including its address
  and its IP, which is why the decision is the site owner’s and not a stranger’s.
• This is deliberately bounded. It never runs while a page is being rendered, it does not
  fan out to the mentions or the audience named in the document, an address already known
  is not fetched again, and only https addresses are considered. Turning the setting off
  also clears anything already queued.

Which servers are contacted therefore depends on which addresses your administrators enter
and which sites send things to your inbox. This plugin has no service of its own and sends
nothing to its author. Each server contacted is somebody else’s, run under its own terms of
service and privacy policy.