pubsub

The pubsub worker is topic-based publish/subscribe messaging. Publish an event to a named topic with the publish function and every registered subscribe trigger whose topic matches is invoked with the raw payload — no envelope, no persistence, no retries. It is fire-and-forget broadcast: subscribers receive each event as it arrives, and a subscriber that is offline simply misses it.

Install it with iii worker add pubsub. It replaces the former built-in iii-pubsub worker: the trigger type (subscribe) and the function id (publish) are unchanged, so existing application code keeps working — only the owner moved from an in-process builtin to this standalone worker.

The worker exposes one callable function (publish, registered with the bare function id "publish" — no namespace prefix) and one trigger type (subscribe). Two adapters: local (default; in-memory broadcast; only delivers to subscribers in this engine process; no external dependency) and redis (redis_url: ${REDIS_URL:redis://localhost:6379}; uses Redis Pub/Sub so events propagate across multiple engine instances). The adapter is set in the pubsub configuration entry and hot-swaps at runtime.

When to Use

• Real-time notifications consumers may miss without consequence — UI live updates, ephemeral signals, telemetry mirroring.
• Loose coupling where an event source should not know about its consumers.
• Cross-instance fan-out of ephemeral events (configure the redis adapter).

Boundaries