The graph

Everything in Anahita is a node, and every relationship between two things is an edge. A person, a group, a post, a hashtag, a location and a feed are nodes; following, liking, tagging, citing and saving are edges. This page is about what the two are, how their types are named, and every type there is.

Why one graph

A school's community holds people, groups, events, notes, articles, photos and videos, and they are all connected: who follows what, who is in which photo, which article cites which note, which posts are about #seeds. Kept as one graph, each of these is read, permitted, searched and suggested in the same way:

• One rule for who may see what, applied in one place, to every kind of node (Who may see a node).
• One shape for search and suggestions to walk: "posts liked by people you follow" and "people cited by people you follow" are the same walk over different edges (How things are found).
• Something new needs no new tables. A custom feed is a node, and keeping it on the home page is an edge (A feed is a node). A post from Mastodon is a node too, so following it, liking it and blocking its author need nothing new.

The graph is owned by one service, graph-grpc-service. Every other service reads and writes it through that one, over gRPC (Architecture).

Nodes

A node is a row of the nodes table. Every kind shares it; what a column means can depend on the kind, and a column a kind has no use for is left empty.

Column	What
id	Its number on this installation
uuid	What another server is told it is called: random, and never changed
type	What kind of node it is (How a type is named)
name, alias, body	What it is called, its handle or address, and what it says
owner_id	The profile it is on: the person or group a post was posted to. On a profile, empty
created_by	Who made it, who need not be its owner: a person's post in a group is owned by the group
parent_id, root_id	On a reply, what it answers and the post at the top of its thread. On a repost, the original
quote_id	On a note that quotes a post, that post
access	Who may see it (Who may see a node)
meta	What one kind keeps that the others do not, as JSON: a feed's definition, for one
uri, origin_domain	What it is called on the server it came from, when it came from another one
follower_count, vote_up_count, comment_count, citation_count, …	Counts the graph keeps in step with the edges, so that a list does not count each time it is read

How a type is named

A type is a name from a fixed grammar, read left to right from the most general to the most particular:

node.<family>.<service>.<entity>.v1      node.actor.person-service.person.v1
edge.<family>.<name>.v1                  edge.actor.follow.v1

• The family is what everything of that kind has in common. Every node.actor. can be followed, blocked and posted to; every node.medium. is a post, with an owner, an author and an audience. Code that asks "is this a profile?" asks whether the type begins with node.actor..
• The service is the one that answers for that kind of node. A group's is still group-service, an older name, because a type is never renamed.
• The version is there because a type is stored for good: in every row, in every edge's node_a_type and node_b_type, and in what other services keep. A change to what a type means would be a new version, read beside the old, never an edit of the old.

Every kind of node

Family	Type	What
Actors	node.actor.person-service.person.v1	A person with an account here
	node.actor.group-service.group.v1	A group, which people follow and post in
	node.actor.actor-service.event.v1	An event, which people say they are going to; often hosted by a group
	node.actor.actor-service.website.v1	A website's feed, verified, as a profile to follow (Websites)
	node.actor.activitypub-service.person.v1	Somebody on a server of the fediverse
	node.actor.atproto-service.person.v1	Somebody on Bluesky
Media	node.medium.text-service.note.v1	A note: a short post, and the kind that arrives from another server
	node.medium.text-service.article.v1	An article: long, with a title; what a website posts for each item of its feed
	node.medium.text-service.topic.v1	A topic: a conversation with a title, started on a profile, with replies under it
	node.medium.photo-service.photo.v1	A photo post, of one or more photos (Photo posts)
	node.medium.video-service.video.v1	A video post (Videos)
Tags	node.tag.hashtag-service.hashtag.v1	A hashtag (Hashtags and locations)
	node.tag.location-service.location.v1	A location posts are tagged with
Feeds	node.feed.feed-service.generator.v1	A custom feed: what it shows, kept in its meta (Custom feeds)
Reposts	node.base.repost-service.repost.v1	A repost: its parent_id is the original, and its owner the profile that reposted it

A reply is a node of the same type as a note, with a parent_id. People elsewhere have types of their own, not the person type with a flag: whatever lists the people of this installation by type then leaves them out without having to be told.

Edges

An edge is a row of the edges table: a type, and two nodes, node_a and node_b, with each one's type beside its id. It points from a to b, and reads as a sentence: Ana follows the library.

Column	What
type	What the relationship is
node_a_id, node_a_type	Where it is from
node_b_id, node_b_type	Where it is to
meta	What it says beyond that, as JSON: whether a tag of a person has been approved, for one
ordering	Its place among its siblings, for the ones kept in an order somebody chose: feeds on the home page
created_by, created_at	Who made it, and when; what fades with time is counted from this

There is one edge of a type between the same two nodes, never two (uc_edge): liking a post twice is liking it.

Every kind of edge

Type	From	To	Means
edge.actor.follow.v1	A profile	A profile	Follows it
edge.actor.follow-request.v1	A profile	A profile	Has asked to follow it, and is waiting for an answer
edge.actor.block.v1	A profile	A profile	Blocks it: neither sees the other
edge.actor.admin.v1	A person	A group or an event	Is one of its administrators
edge.actor.host.v1	A group	An event	Hosts it; what puts it on the group's list of events
edge.actor.invite.v1	A person	A profile	Was invited to follow it, by created_by
edge.base.voteup.v1	A person	A post	Likes it
edge.base.bookmark.v1	A person	A post	Saved it. Private: nobody else is told, the post's author included, and nothing is counted from it
edge.base.subscription.v1	A person	A post or a profile	Is notified of what happens to it (Notifications)
edge.tag.hashtag.v1	A hashtag	A post	The post carries the hashtag
edge.tag.location.v1	A location	A post	The post is tagged with the location
edge.tag.mention.v1	A profile	A post	The post names the profile: "this is for you"
edge.tag.person.v1	A person	A photo or video post	The person is in it, tagged by its author; shown once they approve
edge.medium.citation.v1	A post	A post	The first shows the second within its text, as an article or a topic does an address on a line of its own
edge.medium.hidden-reply.v1	A post	A reply	The reply is hidden from the post's thread; the reply stays its author's
edge.feed.pin.v1	A person	A custom feed	Keeps it on their home page, in the place its ordering says

Who may see a node

Every node has an audience, its access: public, registered, followers, leaders, mutuals, admins or myself, each measured against the profile the node is on, not whoever wrote it (The audiences). A block, either way, hides everything.

The graph applies these to every read, whatever asked: a list, a search, a suggestion, a feed. What a service is sent is already what the viewer may see, so no service has a rule of its own to get wrong (Permissions).

Nodes from other servers

A person on Mastodon or Bluesky, and what they post, are nodes here once somebody here has met them: looked them up, followed them, or been replied to. Each has a uri, what it is called where it lives, and an origin_domain; a node without a uri was made here. See What a node is called elsewhere and Federation.

Events are not types

What happens to the graph is told to the services that care over the bus, RabbitMQ, by events with names in the same grammar and an action at the end: node.medium.text-service.note.added.v1, edge.follow.socialgraph.added.v1. These are the names of things that happened, not of nodes or edges, and are never stored as a type. They are listed in anahita-libs/event (Architecture).

Where the code is

What	Where
The two tables	migration-job/schema/init.sql
The type names	anahita-libs/constants/entity_types.go, and beside the code of the kind (anahita-libs/feeds, anahita-libs/videos, text-service/constants)
The audiences	anahita-libs/constants/access.go
Every read and write	graph-grpc-service/data/repositories
How other services call it	anahita-libs/proto/graphpb, over gRPC (Services over gRPC)