@offlinesync/discovery

Pluggable LAN peer discovery service. Zero dependencies.

DiscoveryService

import { DiscoveryService, InMemoryDiscoveryBackend } from '@offlinesync/discovery'

const discovery = new DiscoveryService({
  backend: new InMemoryDiscoveryBackend(),
  metadata: { name: 'My App' },
})

discovery.onPeerDiscovered((peer) => {
  console.log(`Found peer: ${peer.id} at ${peer.endpoint}`)
})

discovery.onPeerLost((peer) => {
  console.log(`Lost peer: ${peer.id}`)
})

await discovery.start()
// ... later
await discovery.stop()

Options

Option	Type	Description
backend	DiscoveryBackend	Pluggable discovery backend
metadata?	Record<string, unknown>	Metadata sent with this peer

Methods

Method	Returns	Description
start()	Promise<void>	Begin discovery
stop()	Promise<void>	Stop discovery
discover()	Promise<PeerInfo[]>	Get current peer list
onPeerDiscovered(cb)	void	Register peer found callback
onPeerLost(cb)	void	Register peer lost callback

Implementing a Custom Backend

import type { DiscoveryBackend, PeerInfo } from '@offlinesync/discovery'

class MDNSBackend implements DiscoveryBackend {
  async start() { /* ... */ }
  async stop() { /* ... */ }
  onPeerFound?: (peer: PeerInfo) => void
  onPeerLost?: (peer: PeerInfo) => void
}

Types

Export	Description
PeerInfo	{ id, endpoint, metadata? }
DiscoveryBackend	Interface: start(), stop(), onPeerFound?, onPeerLost?
DiscoveryState	`'STOPPED'
DiscoveryError	Discovery-specific error class