@nwire/bus

Cross-service event bus contract — pub/sub for events that leave one service and reach another.

What it does

Defines EventBus, the publish-subscribe contract used to fan domain events across deployable services. Within one service the runtime fans events to in-process actors/projections/reactions; across services those same events flow through this bus (NATS in production, in-memory in tests). Ships InMemoryEventBus for dev/tests; swap in @nwire/nats (or any other adapter) by config.

Install

pnpm add @nwire/bus

Quick start

import { InMemoryEventBus } from "@nwire/bus";
import { createApp } from "@nwire/app";
import { forgePlugins } from "@nwire/forge";

const bus = new InMemoryEventBus();
const app = createApp({
  appName: "learnflow",
  plugins: [...forgePlugins({ bus })],
});
await app.start();
// `.public()` events now drain to the bus; cross-service subscribers can react.

Wiring a bus installs it as the runtime's outbound terminal sink stage — every ctx.publish of a .public() event drains through the runtime's one sink chain and reaches bus.publish exactly once, stamped with the originating app as origin. No bus wired = publish stays local. Outside forge, install the stage directly:

runtime.sink(busSinkStage(bus, { origin: runtime.appName }));

API surface

• EventBus — publish(message) + subscribe(eventName, handler) => unsubscribe.
• InMemoryEventBus — in-process default for tests / single-service deployments.
• busSinkStage(bus, { origin }) — the bus as a terminal sink stage for runtime.sink(...).
• BusEventMessage / BusSubscriber — wire types.

When to use

When the system is deployed as more than one process (split services, microservices).

Within nwire-app

For developers using this package as part of the Nwire stack — register it via app.use(...) or it auto-wires when you compose createApp({ modules }).

import { createApp } from "@nwire/forge";

const app = createApp({
  /* ...config... */
});
// Adapter/plugin wiring happens here when applicable.