Subscriptions

By default Coco will enable Watchers & Processors when instantiating with the initializeCoco helper. Some of these services will try to establish a Websocket connection to the mint to receive live updates. If Websockets are unavailable for whatever reason Coco will fallback to polling.

Websocket Factory

Coco will try to use the global WebSocket object by default. As this is not available in all environments, you can also pass a WebsocketFactory via CocoConfig. Here is an example of how to instantiate Coco with the popular Websocket implementation ws in NodeJS:

import { initializeCoco } from 'coco-cashu-core';
import { WebSocket } from 'ws';

const coco = await initializeCoco({
  repo,
  seedGetter,
  webSocketFactory: (url) => new WebSocket(url),
});

Managing Subscription Lifecycle

Coco provides APIs to pause and resume subscriptions for better resource management:

// Pause all subscriptions when app goes to background
await coco.pauseSubscriptions();

// Resume all subscriptions when app comes to foreground
await coco.resumeSubscriptions();

This is particularly useful for:

• Mobile apps: Save battery when the app is backgrounded
• Web apps: Reduce resource usage when the browser tab is hidden
• Desktop apps: Pause when the window is minimized

Example: React Native App Lifecycle

import { AppState } from 'react-native';

// Listen for app state changes
AppState.addEventListener('change', async (nextAppState) => {
  if (nextAppState === 'background') {
    await coco.pauseSubscriptions();
  } else if (nextAppState === 'active') {
    await coco.resumeSubscriptions();
  }
});

Example: Web Browser Visibility

document.addEventListener('visibilitychange', async () => {
  if (document.hidden) {
    await coco.pauseSubscriptions();
  } else {
    await coco.resumeSubscriptions();
  }
});

See Watchers & Processors for more details on pause/resume behavior.