---
status: draft
last_updated: 2026-05-07
---

# Event Target Adapters

All adapters implement the `TypedEventTarget<TEvent>` interface and use the `EventEnvelope` format (`{ type, id, payload }`) as the serialization contract.

## Interface Contract

Every adapter must implement:

| Method | Behavior |
|--------|----------|
| `addEventListener(type, callback)` | Register listener for event type. Callback receives `CustomEvent` with typed `detail` (an `EventEnvelope`). |
| `dispatchEvent(event)` | Send/dispatch event. Returns `boolean` (always `true` for non-cancelable events). |
| `removeEventListener(type, callback)` | Unregister listener. Clean up underlying subscription when no listeners remain for a topic. |

## Topology Model

Adapters come in two shapes:

- **Symmetric** (single connection) — wraps one connection. Same interface on both sides. Examples: Redis, Iroh spoke, WebSocket client, Worker main-thread.
- **Fan-out** (multi-connection) — manages multiple connections. `dispatchEvent` sends to all; `addEventListener` aggregates from all. Examples: WebSocket server, Iroh hub, Worker pool manager.

The `createPubSub` layer is topology-agnostic. A hub composes multiple adapters and uses operators to combine streams — this is downstream application logic, not a package boundary.

## Adapter Docs

| Adapter | Import | Status |
|---------|--------|--------|
| [In-Process](in-process.md) | (default, no import) | Implemented (built-in `EventTarget`) |
| [Redis](redis.md) | `@alkdev/pubsub/event-target-redis` | Implemented. Needs tests. |
| [WebSocket Client](websocket-client.md) | `@alkdev/pubsub/event-target-websocket-client` | Not yet implemented |
| [WebSocket Server](websocket-server.md) | `@alkdev/pubsub/event-target-websocket-server` | Not yet implemented |
| [Worker](worker.md) | `@alkdev/pubsub/event-target-worker` | Not yet implemented (R&D on Node vs Web Worker) |
| [Iroh Spoke](iroh-spoke.md) | `@alkdev/pubsub/event-target-iroh-spoke` | Not yet implemented (R&D on binding) |
| [Iroh Hub](iroh-hub.md) | `@alkdev/pubsub/event-target-iroh-hub` | Not yet implemented (R&D on binding) |