@corestore/networker


A corestore networking module that uses hyperswarm to discovery peers. This module powers the networking portion of the Hyperspace.

Calls to configure will not be persisted across restarts, so you'll need to use a separate database that maps discovery keys to network configurations. The Hyperdrive daemon uses Level for this.

Since corestore has an all-to-all replication model (any shared cores between two peers will be automatically replicated), only one connection needs to be maintained per peer. If multiple connections are opened to a single peer as a result of that peer announcing many keys, then these connections will be automatically deduplicated by comparing NOISE keypairs.

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This module's going through a major change + a rename as part of our push to develop Hyperspace. With these updates, @corestore/networker and Hyperspace's network APIs are now interchangeable!

If you've previously been using corestore-swarm-networking and you'd like to upgrade, UPGRADE.md explains the changes.

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``
npm i @corestore/networker
`

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`js
const Networker = require('@corestore/networker')
const Corestore = require('corestore')
const ram = require('random-access-memory')

const store = new Corestore(ram)
await store.ready()

const networker = new Networker(store)

// Start announcing or lookup up a discovery key on the DHT.
await networker.configure(discoveryKey, { announce: true, lookup: true })

// Stop announcing or looking up a discovery key.
networker.configure(discoveryKey, { announce: false, lookup: false })

// Shut down the swarm (and unnanounce all keys)
await networker.close()
`

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#### const networker = new Networker(corestore, networkingOptions = {})
Creates a new SwarmNetworker that will open replication streams on the corestore instance argument.

networkOpts is an options map that can include all hyperswarm options (which will be passed to the internal swarm instance) as well as:
`js
{
id: crypto.randomBytes(32), // A randomly-generated peer ID,
keyPair: HypercoreProtocol.keyPair(), // A NOISE keypair that's used across all connections.
onauthenticate: (remotePublicKey, cb) => { cb() }, // A NOISE keypair authentication hook
swarm: hyperswarm(), // A hyperswarm instance to use (e.g., hyperswarm-web in the browser)
}
`

#### networker.peers
The list of currently-connected peers. Each Peer object has the form:
`
{
remotePublicKey: 0xabc..., // The remote peer's NOISE key.
remoteAddress: '10.23.4...:8080', // The remote peer's host/port.
type: 'tcp' | 'utp', // The connection type
stream // The connection's HypercoreProtocol stream
}
`

#### networker.on('peer-add', peer)
Emitted when a new connection has been established with peer.

#### networker.on('peer-remove', peer)
Emitted when peer's connection has been closed.

#### await networker.configure(discoveryKey, opts = {})
Join or leave the swarm with the discoveryKey argument as the topic.

If this is the first time configure has been called, the swarm instance will be created automatically.

Waits for the topic to be fully joined/left before resolving.

opts is an options map of network configuration options that can include:
`js
announce: true, // Announce the discovery key on the swarm
lookup: true // Look up the discovery key on the swarm,
flush: true // Wait for a complete swarm flush before resolving.
`

#### networker.joined(discoveryKey)
Returns true if that discovery key is being swarmed.

#### networker.flushed(discoveryKey)
Returns true if the swarm has discovered and attempted to connect to all peers announcing discoveryKey.

#### networker.listen()
Starts listening for connections on Hyperswarm's default port.

This is called automatically before the first call to configure.

#### await networker.close()
Shut down the swarm networker.

This will close all replication streams and then destroy the swarm instance. It will wait for all topics to be unannounced, so it might take some time.

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@corestore/networker introduces stream-level extensions that operate on each connection. They adhere to Hypercore's extension API.

#### const ext = await networker.registerExtension(name, { encoding, onmessage, onerror })
Registers an extension with name name.

The onmessage and onerror handlers are both optional methods. onerror is an errback, and onmessage must have the signature:

`js
function onmessage (msg, peer) {
// msg is the (optionally-decoded) message that was received from peer.
// peer is a Peer object (described above in networker.peers)
}
`

#### ext.send(msg, peer)
Send msg (which will optionally be encoded by the extension's encoding opt) to peer. peer must be a Peer object taken from networker.peers or emitted by the networker's peer-add event.

#### ext.broadcast(msg)
Broadcast msg to all currently-connected peers.

#### ext.destroy()`
Destroy the extension and unregister it from all connections.

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MIT