@canvas-js/libp2p-rendezvous

libp2p-rendezvous

JavaScript implementation of the libp2p rendezvous protocol.

Table of Contents

• Install
• Usage
• API
  • @canvas-js/libp2p-rendezvous/client
  • @canvas-js/libp2p-rendezvous/server
• Testing
• Contributing
• License

Install

npm i @canvas-js/libp2p-rendezvous

Usage

Rendezvous servers maintain a SQLite database of "registrations", consisting of a string namespace and a signed peer record. Rendezvous clients can register and unregister themselves for arbitrary namespaces, and discover other peer registrations by namespace.

Server

Add the rendezvous server service to a public libp2p peer:

import { rendezvousServer } from "@canvas-js/libp2p-rendezvous/server"

const libp2p = await createLibp2p({
  // ...
  services: {
    // ...
    rendezvous: rendezvousServer({ path: "rendezvous-registrations.sqlite" }),
  },
})

The path is optional; an in-memory SQLite database will be used if it is null or not provided.

Client

Add the rendezvous client service to the peers that need to find each other:

import { rendezvousClient } from "@canvas-js/libp2-rendezvous/client"

const libp2p = await createLibp2p({
  // ...
  services: {
    // ...
    rendezvous: rendezvousClient({
      autoRegister: {
        namespaces: ["topic-a", "topic-b"],
        multiaddrs: ["/dns4/my-rendezvous-server/..."],
      },
      autoDiscover: true,
    }),
  },
})

Providing namespaces and multiaddrs to autoRegister will cause the client to automatically dial those servers on startup, effectively replacing the @libp2p/bootstrap service.

The client service will then register each namespaces with all of the peers that support the rendezvous server protocol, track the returned TTLs, and automatically renew the registrations shortly before expiration, re-connecting to each peer if necessary.

The autoDiscovery feature is enabled by default, which will query for other peers registered under each of the provided namespaces, and emit the results as peer discovery events.

Alternatively, you can choose to manually connect to a server and make register, unregister, and discover calls yourself:

const serverPeerId = peerIdFromString("...")
await libp2p.services.rendezvous.connect(serverPeerId, async (point) => {
  await point.register("topic-a")
  await point.unregister("topic-b")
  const peers = await point.discover("topic-c")
  // peers: { id: PeerId; addresses: { multiaddr: Multiaddr }[]; ... }[]
})

API

@canvas-js/libp2p-rendezvous/client

import type { TypedEventTarget, Libp2pEvents, PeerId, PeerStore, Peer, Connection } from "@libp2p/interface"
import type { Registrar, AddressManager, ConnectionManager } from "@libp2p/interface-internal"
import type { Multiaddr } from "@multiformats/multiaddr"

export interface RendezvousPoint {
  discover(namespace: string, options?: { limit?: number }): Promise<Peer[]>
  register(namespace: string, options?: { ttl?: number | null; multiaddrs?: Multiaddr[] }): Promise<{ ttl: number }>
  unregister(namespace: string): Promise<void>
}

export type RendezvousClientComponents = {
  /** internal libp2p components */
}

export interface RendezvousClientInit {
  autoRegister?: {
    /** namespaces to auto-register */
    namespaces: string[]
    /** rendezvous point multiaddrs */
    multiaddrs: string[]

    /** registration TTL, in seconds */
    ttl?: number
    /** initial timeout before connecting, in milliseconds */
    initialTimeout?: number
    /** retry interval between failed connections, in milliseconds */
    retryInterval?: number
  }

  /** auto-discover registered namespaces, and add them to the peer store */
  autoDiscover?: boolean
  /** auto-discovery inverval, in milliseconds */
  autoDiscoverInterval?: number
}

export declare class RendezvousClient {
  public static protocol = "/canvas/rendezvous/1.0.0"

  public connect<T>(
    server: PeerId | Multiaddr | Multiaddr[],
    callback: (point: RendezvousPoint) => T | Promise<T>,
  ): Promise<T>
}

export declare const rendezvousClient: (
  init?: RendezvousClientInit,
) => (components: RendezvousClientComponents) => RendezvousClient

@canvas-js/libp2p-rendezvous/server

import { TypedEventTarget, Libp2pEvents, PeerId, PeerStore } from "@libp2p/interface"
import { Registrar, AddressManager, ConnectionManager } from "@libp2p/interface-internal"

export type RendezvousServerComponents = {
  /** internal libp2p components */
}

export interface RendezvousServerInit {
  path?: string | null
}

export declare class RendezvousServer implements Startable {
  public static protocol = "/canvas/rendezvous/1.0.0"

  public constructor(components: RendezvousServerComponents, init: RendezvousServerInit)
}

export declare const rendezvousServer: (
  init?: RendezvousServerInit,
) => (components: RendezvousServerComponents) => RendezvousServer

Testing

Tests use AVA and live in the test directory.

npm run test

Contributing

Open an issue if you have questions, find bugs, or have interface suggestions. Only minor PRs will be considered without prior discussion.

License

MIT © Canvas Technologies, Inc.