Activitypub on emsenn.net

Standardization as Counterinsurgency

Tue, 03 Mar 2026 00:00:00 +0000

This concept has a full treatment at technology/concepts/internet/topics/activitypub/concepts/standardization-as-counterinsurgency.

Activity

Wed, 31 Dec 2025 00:00:00 +0000

An Activity is the basic unit of interaction in ActivityPub. It’s a verb-object pair — an action performed by an Actor on some target — expressed in the ActivityStreams 2.0 vocabulary and distributed across the federation via server-to-server delivery.

Standard activity types include Create (publishing a post), Follow (subscribing to an actor’s output), Like (signaling approval), Announce (resharing), and Delete (removing content). The vocabulary is extensible: implementations can define custom activity types, though interoperability depends on receivers understanding them.

ActivityPub Overview

Wed, 31 Dec 2025 00:00:00 +0000

ActivityPub defines how servers and clients exchange activities in a federated social network.

Actor

Wed, 31 Dec 2025 00:00:00 +0000

An Actor is an addressable entity in ActivityPub — a user account, a bot, a service, or any other thing that can send and receive activities. Each actor has an inbox (where it receives activities from the federation) and an outbox (where it publishes activities).

Actors are identified by URLs and discoverable via WebFinger. The protocol makes no distinction between an actor on a single-person instance and an actor on a server with millions of users — a design choice that preserves formal equality but doesn’t address the power asymmetries between volunteer-run instances and corporate-scale deployments. This is one of the points where the standardization process bracketed political questions as “out of scope”: the specification treats all actors as equivalent nodes, regardless of the resources and governance behind them.

Federation

Wed, 31 Dec 2025 00:00:00 +0000

Federation is the network architecture in which autonomous servers exchange activities via a shared protocol — in this case, ActivityPub. Each server (instance) operates independently: it runs its own moderation policies, stores its own data, and decides which other instances to communicate with. Federation means these independent servers can interoperate, allowing users on one instance to follow, message, and interact with users on another.

The key property of federation is that no single server controls the network. An instance can join or leave the federation, block specific other instances, or modify how it processes incoming activities. This is what gave the early fediverse its character as an insurgent infrastructure: anyone could spin up a server and participate on equal technical footing.