js-libp2p/doc/API.md

API

• Static Functions
  • create
• Instance Methods
  • start
  • stop
  • dial
  • dialProtocol
  • hangUp
  • handle
  • unhandle
  • peerRouting.findPeer
  • contentRouting.findProviders
  • contentRouting.provide
  • contentRouting.put
  • contentRouting.get
  • contentRouting.getMany
  • pubsub.getSubscribers
  • pubsub.getTopics
  • pubsub.publish
  • pubsub.subscribe

Static Functions

create

Creates an instance of Libp2p.

create(options)

Parameters

Name	Type	Description
options	Object	libp2p options
options.modules	Array<Object>	libp2p modules to use
[options.config]	Object	libp2p modules configuration and core configuration
[options.datastore]	Object	must implement ipfs/interface-datastore (in memory datastore will be used if not provided)
[options.peerInfo]	PeerInfo	peerInfo instance (it will be created if not provided)

For Libp2p configurations and modules details read the Configuration Document.

Returns

Type	Description
Promise<Libp2p>	Promise resolves with the Libp2p instance

Example

const Libp2p = require('libp2p')

// specify options
const options = {}

// create libp2p
const libp2p = await Libp2p.create(options)

Note: The PeerInfo option is not required and will be generated if it is not provided.

Alternative

As an alternative, it is possible to create a Libp2p instance with the constructor:

Example

const Libp2p = require('libp2p')

// specify options
const options = {}

// create libp2p
const libp2p = new Libp2p(options)

Required keys in the options object:

• peerInfo: instance of [PeerInfo][] that contains the [PeerId][], Keys and [multiaddrs][multiaddr] of the libp2p Node (optional when using .create).
• modules.transport: An array that must include at least 1 compliant transport. See modules that implement the transport interface.

Once you have a libp2p instance, you are able to listen to several events it emmits, so that you can be noticed of relevant network events.

Events

An error has occurred

libp2p.on('error', (err) => {})

• err: instance of Error

A peer has been discovered

libp2p.on('peer:discovery', (peer) => {})

If autoDial option is true, applications should not attempt to connect to the peer unless they are performing a specific action. See peer discovery and auto dial for more information.

• peer: instance of [PeerInfo][https://github.com/libp2p/js-peer-info]

We have a new connection to a peer

libp2p.on('peer:connect', (peer) => {})

• peer: instance of [PeerInfo][https://github.com/libp2p/js-peer-info]

We have closed a connection to a peer

libp2p.on('peer:disconnect', (peer) => {})

• peer: instance of [PeerInfo][https://github.com/libp2p/js-peer-info]

Libp2p Instance Methods

start

Starts the libp2p node.

libp2p.start()

Returns

Type	Description
Promise	Promise resolves when the node is ready

Example

const Libp2p = require('libp2p')

// ...

const libp2p = await Libp2p.create(options)

// start libp2p
await libp2p.start()

stop

Stops the libp2p node.

libp2p.stop()

Returns

Type	Description
Promise	Promise resolves when the node is fully stopped

Example

const Libp2p = require('libp2p')

// ...
const libp2p = await Libp2p.create(options)
// ...

// stop libp2p
await libp2p.stop()

dial

Dials to another peer in the network and establishes the connection.

dial(peer, options)

Parameters

Name	Type	Description
peer	PeerInfo, PeerId, multiaddr, string	peer to dial
[options]	Object	dial options
[options.signal]	AbortSignal	An AbortSignal instance obtained from an AbortController that can be used to abort the connection before it completes

Returns

Type	Description
Promise<Connection>	Promise resolves with the Connection instance

Example

// ...
const conn = await libp2p.dial(remotePeerInfo)

// create a new stream within the connection
const { stream, protocol } = await conn.newStream(['/echo/1.1.0', '/echo/1.0.0'])

// protocol negotiated: 'echo/1.0.0' means that the other party only supports the older version

// ...
await conn.close()

dialProtocol

Dials to another peer in the network and selects a protocol to communicate with that peer. The stream between both parties is returned, together with the negotiated protocol.

dialProtocol(peer, protocols, options)

Parameters

Name	Type	Description
peer	PeerInfo, PeerId, multiaddr, string	peer to dial
protocols	`String	Array`
[options]	Object	dial options
[options.signal]	AbortSignal	An AbortSignal instance obtained from an AbortController that can be used to abort the connection before it completes

Returns

Type	Description
Promise<{ stream:*, protocol:string }>	Promise resolves with a duplex stream and the protocol used

Example

// ...
const pipe = require('it-pipe')

const { stream, protocol } = await libp2p.dialProtocol(remotePeerInfo, protocols)

// Use this new stream like any other duplex stream
pipe([1, 2, 3], stream, consume)

hangUp

Attempts to gracefully close an open connection to the given peer. If the connection is not closed in the grace period, it will be forcefully closed.

hangUp(peer)

Parameters

Name	Type	Description
peer	PeerInfo, PeerId, multiaddr, string	peer to hang up

Returns

Type	Description
Promise<void>	Promise resolves once connection closes

Example

// ...
await libp2p.hangUp(remotePeerInfo)

handle

Sets up multistream-select routing of protocols to their application handlers. Whenever a stream is opened on one of the provided protocols, the handler will be called. handle must be called in order to register a handler and support for a given protocol. This also informs other peers of the protocols you support.

libp2p.handle(protocols, handler)

In the event of a new handler for the same protocol being added, the first one is discarded.

Parameters

Name	Type	Description
protocols	`Array	String`
handler	function({ connection:*, stream:*, protocol:string })	handler to call

Example

// ...
const handler = ({ connection, stream, protocol }) => {
  // use stream or connection according to the needs
}

libp2p.handle('/echo/1.0.0', handler)

unhandle

Unregisters all handlers with the given protocols

libp2p.unhandle(protocols)

Parameters

Name	Type	Description
protocols	`Array	String`

Example

// ...
libp2p.unhandle(['/echo/1.0.0'])

peerRouting.findPeer

Iterates over all peer routers in series to find the given peer. If the DHT is enabled, it will be tried first.

libp2p.peerRouting.findPeer(peerId, options)

Parameters

Name	Type	Description
peerId	PeerId	ID of the peer to find
options	Object	operation options
options.timeout	number	maximum time the query should run

Returns

Type	Description
Promise<PeerInfo>	Peer info of a known peer

Example

// ...
const peerInfo = await libp2p.peerRouting.findPeer(peerId, options)

contentRouting.findProviders

Iterates over all content routers in series to find providers of the given key. Once a content router succeeds, the iteration will stop. If the DHT is enabled, it will be queried first.

libp2p.contentRouting.findProviders(cid, options)

Parameters

Name	Type	Description
cid	CID	cid to find
options	Object	operation options
options.timeout	number	maximum time the query should run
options.maxNumProviders	number	maximum number of providers to find

Returns

Type	Description
AsyncIterator<PeerInfo>	Async iterator for PeerInfo

Example

// Iterate over the providers found for the given cid
for await (const provider of libp2p.contentRouting.findProviders(cid)) {
  console.log(provider)
}

contentRouting.provide

Iterates over all content routers in parallel, in order to notify it is a provider of the given key.

libp2p.contentRouting.provide(cid)

Parameters

Name	Type	Description
cid	CID	cid to provide

Returns

Type	Description
Promise<void>	Promise resolves once notifications are sent

Example

// ...
await libp2p.contentRouting.provide(cid)

contentRouting.put

Writes a value to a key in the DHT.

libp2p.contentRouting.put(key, value, options)

Parameters

Name	Type	Description
key	String	key to add to the dht
value	Buffer	value to add to the dht
[options]	Object	put options
[options.minPeers]	number	minimum number of peers required to successfully put (default: closestPeers.length)

Returns

Type	Description
Promise<void>	Promise resolves once value is stored

Example

// ...
const key = '/key'
const value = Buffer.from('oh hello there')

await libp2p.contentRouting.put(key, value)

contentRouting.get

Queries the DHT for a value stored for a given key.

libp2p.contentRouting.get(key, options)

Parameters

Name	Type	Description
key	String	key to get from the dht
[options]	Object	get options
[options.timeout]	number	maximum time the query should run

Returns

Type	Description
Promise<Buffer>	Value obtained from the DHT

Example

// ...

const key = '/key'
const value = await libp2p.contentRouting.get(key)

contentRouting.getMany

Queries the DHT for the n values stored for the given key (without sorting).

libp2p.contentRouting.getMany(key, nvals, options)

Parameters

Name	Type	Description
key	String	key to get from the dht
nvals	number	number of values aimed
[options]	Object	get options
[options.timeout]	number	maximum time the query should run

Returns

Type	Description
Promise<Array<{from: PeerId, val: Buffer}>>	Array of records obtained from the DHT

Example

// ...

const key = '/key'
const { from, val } = await libp2p.contentRouting.get(key)

pubsub.getSubscribers

Gets a list of the peer-ids that are subscribed to one topic.

libp2p.pubsub.getSubscribers(topic)

Parameters

Name	Type	Description
topic	string	topic to publish

Returns

Type	Description
Array<String>	peer-id subscribed to the topic

Example

const peerIds = libp2p.pubsub.getSubscribers(topic)

pubsub.getTopics

Gets a list of topics the node is subscribed to.

libp2p.pubsub.getTopics()

Returns

Type	Description
Array<String>	topics the node is subscribed to

Example

const topics = libp2p.pubsub.getTopics()

pubsub.publish

Publishes messages to the given topics.

libp2p.pubsub.publish(topic, data)

Parameters

Name	Type	Description
topic	string	topic to publish
data	Buffer	data to publish

Returns

Type	Description
Promise	publish success

Example

const topic = 'topic'
const data = Buffer.from('data')

await libp2p.pubsub.publish(topic, data)

pubsub.subscribe

Subscribes the given handler to a pubsub topic.

libp2p.pubsub.subscribe(topic, handler)

Parameters

Name	Type	Description
topic	string	topic to subscribe
handler	function({ from: String, data: Buffer, seqno: Buffer, topicIDs: Array<String>, signature: Buffer, key: Buffer })	handler for new data on topic

Returns

Type	Description
void

Example

const topic = 'topic'
const handler = (msg) => {
  // msg.data - pubsub data received
}

libp2p.pubsub.subscribe(topic, handler)

pubsub.unsubscribe

Unsubscribes the given handler from a pubsub topic. If no handler is provided, all handlers for the topic are removed.

libp2p.pubsub.unsubscribe(topic, handler)

Parameters

Name	Type	Description
topic	string	topic to unsubscribe
handler	function(<Object>)	handler subscribed

Returns

Type	Description
void

Example

const topic = 'topic'
const handler = (msg) => {
  // msg.data - pubsub data received
}

libp2p.pubsub.unsubscribe(topic, handler)