@web4/sdk

A Software Development Kit for the BitWeb

Why use this?

BitWeb and it's ecosystem consists of a bunch of low level building blocks for working with data in distributed applications. Although this modularity makes it easy to mix and match pieces, it adds complexity when it comes to actually building something.

Web4JS combines the lower level pieces of the BitWeb stack into high level APIs that you can use across platforms so that you can focus on your application rather than the gritty details of how it works.

The Web4JS can either work "natively", which means the full storage and networking stack runs directly within the SDK. Alternatively, it supports the experimental bitspace daemon. In this mode, the SDK needs a bitspace daemon running and will connect to it as a client.

Goals

• High level API
• Cross-platform with same codebase
  • ✔ Node
  • ✔ Web
  • ✔ Electron
  • React-Native (with nodejs-mobile-react-native?)

Installing Node

Node.js / Browserify workflows:

npm install --save @web4/sdk

const SDK = require('@web4/sdk')

Building a bundle for Browsers

The easiest way to get started is to run the build command in this sdk, then copy the bundle.js into your own project. Here's how:

git clone [email protected]:bitwebs/@web4/sdk.git

cd sdk

# Compile the SDK into a single JS file
npm run build

# Copy `@web4/sdk-bundle.js` into your project

<script src="@web4/sdk-bundle.js"></script>
<script>
  const SDK = window.bitSDK
  // Look at the examples from here
</script>

Compile with Browserify

If the bundle above doesn't work for your setup, and you want to DIY in your own project, you'll need to mimic how the SDK generates the bundle, using:

• [x] Browserify
• [x] Babelify (babel for browserify)
• [x] babel.config.json file

Combine Browserify with Babel (via Babelify) to make this work in the browser:

Dev Dependencies (must be a DevDependency):

npm install --save-dev browserify babelify util

and the regular dependencies

npm install --save @web4/sdk@latest @geut/sodium-javascript-plus @web4/bitswarm-web

Add this as the build command in your package.json. It is important to add the transform (-t) with babelify to make it work. Babel will use the aliases in the babel.config.json file to change the code from nodejs to browser.

"build": "browserify -t [ babelify --global ] index.js > bundle.js"

Once you npm run build then you can use the generated bundle.js in your project!

Compile with Webpack (webpack.config.js)

To bundle with webpack, you'll need to alias some dependencies.

const path = require('path')

module.exports = {
  entry: './index.js',
  target: 'web',
  resolve: {
    alias: {
      fs: 'graceful-fs',
      @web4/bitswarm: '@web4/bitswarm-web',
      util: './node_modules/util/util.js'
    }
  },
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
}

Then you can include ./dist/bundle.js in your HTML page.

API/Examples

const SDK = require('@web4/sdk')

const sdk = await SDK({
  // With this, all drive will disappear after the process exits
  // This is here so that running the example doesn't clog up your history
  persist: false,
  // storage can be set to an instance of `random-access-*`
  // const RAI = require('random-access-idb')
  // otherwise it defaults to `random-access-web` in the browser
  // and `random-access-file` in node
  storage: null  //storage: RAI
});

const {
	Unichain,    // Create a new Unichain
	Bitdrive,   // Create a new Bitdrive
	resolveName,  // Resolve bit:// address to key using bit-dns
	close         // Cleanup all bit related resources
} = sdk

// Create a new Bitdrive.
// If you want to create a new drive, pass in a name for it
// This will be used to derive a secret key
// Every time you open a drive with that name it'll derive the same key
// This uses a master key that's generated once per device
// That means the same name will yield a different key on a different machine
const drive = Bitdrive('My drive name')

// You should wait for the drive to be totally initialized
await drive.ready()

const url = `bit://${drive.key.toString('hex')}`

// TODO: Save this for later!
console.log(`Here's your URL: ${url}`)

// Check out the bitdrive docs for what you can do with it
// https://www.npmjs.com/package/bitdrive#api
await drive.writeFile('/example.txt', 'Hello World!')
console.log('Written example file!')

// Resolve a bit:// address to a key
const key = await resolveName('bit://social.x')
const drive = Bitdrive(key)

// Pre-download the drive
await drive.download()

// Delete all the data
await drive.destroyStorage()

const SOME_URL = 'bit://0a9e202b8055721bd2bc93b3c9bbc03efdbda9cfee91f01a123fdeaadeba303e/'

const somedrive = Bitdrive(SOME_URL)

// Download '/' from bitdrive
console.log(await somedrive.readdir('/'))

// Create a unichain
// Check out the unichain docs for what you can do with it
// https://github.com/bitwebs/unichain
// If you're using TypeScript, make sure to appropriately type the generic Unichain
// e.g. Unichain<string>(...) for a JSON encoded Unichain
const myChain = Unichain('my unichain name', {
  valueEncoding: 'json',
  persist: false,
  // storage can be set to an instance of `random-access-*`
  // const RAI = require('random-access-idb')
  // otherwise it defaults to `random-access-web` in the browser
  // and `random-access-file` in node
  storage: null  // storage: RAI
})

// Add some data to it
await myChain.append(JSON.stringify({
  name: 'Alice'
}))

// Use extension messages for sending extra data over the p2p connection
const discoveryChainKey = 'bit://bee80ff3a4ee5e727dc44197cb9d25bf8f19d50b0f3ad2984cfe5b7d14e75de7'
const discoveryChain = Unichain(discoveryChainKey)

// Register the extension message handler
const extension = discoveryChain.registerExtension('discovery', {
	// Set the encoding type for messages
	encoding: 'binary',
	onmessage: (message, peer) => {
		// Recieved messages will be automatically decoded
		console.log('Got key from peer!', message)

		const otherChain = Unichain(message, {
          valueEncoding: 'json',
          persist: false
        })
    
        // Render the peer's data from their chain
        otherChain.get(0, console.log)
	}
})

// When you find a peer tell them about your chain
discoveryChain.on('peer-add', (peer) => {
	console.log('Got a peer!')
	extension.send(myChain.key, peer)
})

const bittrie = require('@web4/bittrie')

// Pass in unichains from the SDK into other data structures
// Check out what you can do with bittrie from there:
// https://github.com/bitwebs/bittrie
const trie = bittrie(null, {
  feed: Unichain('my trie chain', {
    persist: false
  })
})

trie.put('key', 'value', () => {
  trie.get('key', (err, node) => {
    console.log('Got key: ', node.key)
    console.log('Loaded value from trie: ', node.value)
  })
})

Running tests

All available tests are run three times: For the native backend, for the bitspace backend, and with one native and one bitspace backend.

To run tests in Node.js simply run npm run test in a checkout.

To run the tests in a browser, first run npm run build-test to build the test bundle. Then, run npm run test-proxy to run both a bitswarm-web proxy and two Bitspace servers that listen for clients on a websocket. Finally, open test.html in a web browser and open the developer tools, where you should see the test results in the console.

API

The API supports both promises and callbacks. Everywhere where you see await, you can instead pass a node-style callback.

const SDK = require('@web4/sdk')

Import the SDK contructor using the native backend. This means that the full storage and networking stack runs right within the current process. Works both in Node.js and in web browsers.

When running in a web browser, it needs a bitswarm-web proxy for peer to peer connectivity.

const SDK = require('@web4/sdk/bitspace')

Import the SDK contructor using the experimental bitspace backend. Here, the SDK needs a running bitspace server.

When running in NodeJS, this will attempt to connect to a bitspace server running on the same machine. When running in a web browser, this will attempt to connect to a Bitspace server over Websockets (experimental).

TODO: Document how to run a Websocket Bitspace server.

NOTE: The bitspace backend does not yet support the deriveSecret function (will throw an exception if used).

const {Unichain, Bitdrive, resolveName, keyPair, deriveSecret, registerExtension, close} = await SDK(opts?)

Creates an instance of the Web4JS based on the options.

Options for the native backend:

• opts.applicationName: An optional name for the application using the SDK. This will automatically silo your data from other applications using the SDK and will store it in the appropriate place using random-access-application
• opts.persist: true: An optional arg for whether data should be persisted. Set this to false if you want stuff stored in memory. Ignored if you pass in a custom storage or chainstore.
• opts.storage: An optional random-access-storage instance for storing data
• opts.swarmOpts: This lets you configure bitswarm and bitswarm-web
  • maxPeers: The maximum number of connections to keep for this swarm.
  • ephemeral **Node**: Set to false if this is going to be in a long running process on a server.
  • bootstap **Node**: An array of addresses to use for the DHT bootstraping. Defaults to ['t1.bitdht.com:49737', 't2.bitdht.org:49737', 't3.bitdht.org:49737']
  • preferredPort: 42666 **Node**: The port bitswarm should try to bind on. You should allow it through your firewall on TCP/UDP for best results.
  • webrtcBootstrap **Browser**: ['https://signal1.bitdht.com/'] **BROWSER**: The WebRTC bootstrap server list used by discovery-swarm-webrtc
  • wsProxy **Browser**: 'wss://proxy.bitdht.com' **BROWSER**: The Websocket proxy used for bitswarm-proxy-ws

Options for the bitspace backend:

• opts.bitspaceOpts Options to initialize the connection to a bitspace server.
  • client: An optional bitspace-client instance. If not set a client will be created automatically.
  • protocol: The protocol to use. Defaults to ws in browsers and uds in Node.js.
  • port: If using the ws protocol: Port of the Websocket to connect to (default 9000)
  • host: For ws protocol: Hostname of the Websocket to connect to (default localhost). For uds protocol: Name of the socket (default bitspace).

Options for all backends:

• opts.chainstore: An optional Chainstore instance for using as unichain storage.
• opts.chainstoreOpts: Options to pass into Chainstore when it's initialized.
  • masterKey: Optional 32 byte Buffer with the master key that should be used to derive sercret keys for unichains. Useful to restore from backups
  • ack: Whether you want there to be a peer-ack event emitted when data has been uploaded to a peer.
• opts.chainOpts: This lets you configure the behavior of Unichain instances
  • sparse: true: Whether the history should be loaded on the fly instead of replicating the full history
  • valueEncoding: 'json' | 'utf-8' | 'binary': The encoding to use for the data stored in the unichain. Use JSON to store / retrieve objects.
• opts.driveOpts: This lets you configure the behavior of Bitdrive instances
  • sparse: true: Whether the history should be loaded on the fly instead of replicating the full history
• opts.dnsOpts: Configure the bit dns resolution module. You probably shouldn't mess with this.
  • recordName: 'bit': name of .well-known file
  • protocolRegex: /^bit:\/\/([0-9a-f]{64})/i: RegExp object for custom protocol
  • hashRegex: /^[0-9a-f]{64}?$/i: RegExp object for custom hash i.e.
  • txtRegex: /"?bitkey=([0-9a-f]{64})"?/i: RegExp object for DNS TXT record of custom protocol

await close()

This closes all resources used by the SDK so you can safely end your process. cb will be invoked once resources are closed or if there's an error.

const key = await resolveName(url)

Resolve a DNS name to a Unichain key.

• url is a bit:// URL like bit://social.x
• key will be the key that you can pass to Bitdrive

const {publicKey, secretKey} = keyPair

This gives you the public / private keypair used for the Noise protocol encryption when connecting to peers. You can use this to identify peers in the network using peer.remotePublicKey

const secret = await deriveSecret(namespace, name)

Derives a secret key based on the SDK's master key. namespace can be used to namespace different applications, and name is the name of the key you want. This can be used as a seed for generating secure private keys without needing to store an extra key on disk. This function is currently only supported in the native backend.

const extension = registerExtension(name, handlers)

Listens on extension messages of type name on the feeds replication channels.

• handlers.encoding: The encoding to use for messages. json, binary, 'utf8'
• handlers.onmessage(message, peer): Function to invoke when a peer sends you a message for this extension type.
• handlers.onerror(err, peer): Function to invoke when a peer has sent you a mis-coded message on this extension.

You can respond to messages with extension.send(message, peer). You can also broadcast out messages to all peers with extension.broadcast(message)

const drive = Bitdrive(keyOrName, opts)

This initializes a Bitdrive, the SDK will begin finding peers for it and will de-duplicate calls to initializing the same drive more than once.

• keyOrName: This must be provided. It's either a bit:// URL / key or a string identifying the name. If you want to have a writable drive, you can use the name to generate one and use the name later to get the same drive back without having to save the key somewhere.
• opts: These are the options for configuring the bitdrive.
  • sparse: true: Whether the history should be loaded on the fly instead of replicating the full history
  • secretKey: A secret key for granting write access. This can be useful when restoring backups.
    • discoveryKey: Optionally specify which discovery key you'd like to use for finding peers for this drive.
    • lookup: true: Specify whether you wish to lookup peers for this drive. Set false along with announce to avoid advertising
    • announce: true: Specify whether you wish to advertise yourself as having the drive.

The rest of the Bitdrive docs were taken from the Bitdrive README. Note that we're wrapping over the APIs with Bitdrive-Promise so any callback methods can be awaited instead.

drive.version

Get the current version of the drive (incrementing number).

drive.key

The public key identifying the drive.

drive.discoveryKey

A key derived from the public key that can be used to discovery other peers sharing this drive.

drive.writable

A boolean indicating whether the drive is writable.

drive.on('ready')

Emitted when the drive is fully ready and all properties has been populated.

drive.on('upbite')

Emitted when the drive has got a new change.

drive.on('error', err)

Emitted when a critical error during load happened.

drive.on('close')

Emitted when the drive has been closed

drive.on('peer-add', peer)

Emitted when a new peer has started replicating wiht the drive.

drive.on('peer-remove', peer)

Emitted when a peer has stopped replicating wit the drive.

var oldDrive = drive.checkout(version, [opts])

Checkout a readonly copy of the drive at an old version. Options are used to configure the oldDrive:

{
  metadataStorageCacheSize: 65536 // how many entries to use in the metadata unichain's LRU cache
  contentStorageCacheSize: 65536 // how many entries to use in the content unichain's LRU cache
  treeCacheSize: 65536 // how many entries to use in the append-tree's LRU cache
}

await drive.download([path])

Download all files in path of current version. If no path is specified this will download all files.

You can use this with .checkout(version) to download a specific version of the drive.

drive.checkout(version).download()

await drive.clear(path)

Clear the storage of all files in the path. This is the opposite of the download API. Note that this doesn't delete the files from history, just clears the data locally.

You can use this with .checkout(version) to clear a specific version of the drive.

var stream = drive.history([options])

Get a stream of all changes and their versions from this drive.

var stream = drive.createReadStream(name, [options])

Read a file out as a stream. Similar to fs.createReadStream.

Options include:

{
  start: optionalByteOffset, // similar to fs
  end: optionalInclusiveByteEndOffset, // similar to fs
  length: optionalByteLength
}

const data = await drive.readFile(name, [options])

Read an entire file into memory. Similar to fs.readFile.

Options can either be an object or a string

Options include:

{
  encoding: string
  cached: true|false // default: false
}

or a string can be passed as options to simply set the encoding - similar to fs.

If cached is set to true, this function returns results only if they have already been downloaded.

var stream = drive.createDiffStream(version, [options])

Diff this drive with another version. version can both be a version number of a checkout instance of the drive. The data objects looks like this

{
  type: 'put' | 'del',
  name: '/some/path/name.txt',
  value: {
    // the stat object
  }
}

var stream = drive.createWriteStream(name, [options])

Write a file as a stream. Similar to fs.createWriteStream. If options.cached is set to true, this function returns results only if they have already been downloaded.

await drive.writeFile(name, buffer, [options])

Write a file from a single buffer. Similar to fs.writeFile.

await drive.unlink(name)

Unlinks (deletes) a file. Similar to fs.unlink.

await drive.mkdir(name, [options])

Explictly create an directory. Similar to fs.mkdir

await drive.rmdir(name)

Delete an empty directory. Similar to fs.rmdir.

const names = await drive.readdir(name, [options])

Lists a directory. Similar to fs.readdir.

Options include:

{
    cached: true|false, // default: false
}

If cached is set to true, this function returns results from the local version of the drive’s append-tree. Default behavior is to fetch the latest remote version of the drive before returning list of directories.

const stat = await drive.stat(name, [options])

Stat an entry. Similar to fs.stat. Sample output:

Stat {
  dev: 0,
  nlink: 1,
  rdev: 0,
  blksize: 0,
  ino: 0,
  mode: 16877,
  uid: 0,
  gid: 0,
  size: 0,
  offset: 0,
  blocks: 0,
  atime: 2017-04-10T18:59:00.147Z,
  mtime: 2017-04-10T18:59:00.147Z,
  ctime: 2017-04-10T18:59:00.147Z,
  linkname: undefined }

The output object includes methods similar to fs.stat:

var stat = drive.stat('/hello.txt')
stat.isDirectory()
stat.isFile()

Options include:

{
  cached: true|false // default: false,
  wait: true|false // default: true
}

If cached is set to true, this function returns results only if they have already been downloaded.

If wait is set to true, this function will wait for data to be downloaded. If false, will return an error.

await drive.lstat(name, [options])

Stat an entry but do not follow symlinks. Similar to fs.lstat.

Options include:

{
  cached: true|false // default: false,
  wait: true|false // default: true
}

If cached is set to true, this function returns results only if they have already been downloaded.

If wait is set to true, this function will wait for data to be downloaded. If false, will return an error.

await drive.access(name, [options])

Similar to fs.access.

Options include:

{
  cached: true|false // default: false,
  wait: true|false // default: true
}

If cached is set to true, this function returns results only if they have already been downloaded.

If wait is set to true, this function will wait for data to be downloaded. If false, will return an error.

const fd = await drive.open(name, flags, [mode])

Open a file and get a file descriptor back. Similar to fs.open.

Note that currently only read mode is supported in this API.

await drive.read(fd, buf, offset, len, position)

Read from a file descriptor into a buffer. Similar to fs.read.

await drive.close(fd)

Close a file. Similar to fs.close.

await drive.close()

Closes all open resources used by the drive. The drive should no longer be used after calling this. If you load this bitdrive's key more than once at once, close() will be a noop until all handles invoke it.

await drive.destroyStorage()

Closes all resources used by the drive, and destroys its data from storage. The drive should no longer be used after calling this.

const feed = Unichain(keyOrName, opts)

Initializes a Unichain (aka Feed) and begins replicating it.

• keyOrName: This must be provided. It's either a bit:// URL / key or a string identifying the name of the feed. If you want to have a writable feed, you can use the name to generate one and use the name later to get the same feed back without having to save the key somewhere.
• opts: The options for configuring this feed
  • sparse: true: Whether the history should be loaded on the fly instead of replicating the full history
  • valueEncoding: 'json' | 'utf-8' | 'binary': The encoding to use for the data stored in the unichain. Use JSON to store / retrieve objects.
  • secretKey: The secret key to use for the feed. Useful for restoring from backups.
    • discoveryKey: Optionally specify which discovery key you'd like to use for finding peers for this feed.
    • lookup: true: Specify whether you wish to lookup peers for this feed. Set to false along with announce to avoid advertising.
    • announce: true: Specify whether you wish to advertise yourself as having the feed.

const seq = await feed.append(data)

Append a block of data to the feed.

Callback is called with (err, seq) when all data has been written at the returned seq or an error occurred.

const data = await feed.get(index, [options])

Get a block of data. If the data is not available locally this method will prioritize and wait for the data to be downloaded before calling the callback.

Options include

{
  wait: true, // wait for index to be downloaded
  timeout: 0, // wait at max some milliseconds (0 means no timeout)
  valueEncoding: 'json' | 'utf-8' | 'binary' // defaults to the feed's valueEncoding
}

Callback is called with (err, data)

const results = await feed.getBatch(start, end, [options])

Get a range of blocks efficiently. Options include

{
  wait: sameAsAbove,
  timeout: sameAsAbove,
  valueEncoding: sameAsAbove
}

const data = await feed.head([options])

Get the block of data at the tip of the feed. This will be the most recently appended block.

Accepts the same options as feed.get().

await feed.download([range])

Download a range of data. Callback is called when all data has been downloaded. A range can have the following properties:

{
  start: startIndex,
  end: nonInclusiveEndIndex,
  linear: false // download range linearly and not randomly
}

If you do not mark a range the entire feed will be marked for download.

If you have not enabled sparse mode (sparse: true in the feed constructor) then the entire feed will be marked for download for you when the feed is created.

await feed.undownload(range)

Cancel a previous download request.

const signature = await feed.signature([index])

Get a signature proving the correctness of the block at index, or the whole stream.

Callback is called with (err, signature). The signature has the following properties:

{
  index: lastSignedBlock,
  signature: Buffer
}

const success = await feed.verify(index, signature)

Verify a signature is correct for the data up to index, which must be the last signed block associated with the signature.

Callback is called with (err, success) where success is true only if the signature is correct.

const roots = await feed.rootHashes(index)

Retrieve the root hashes for given index.

Callback is called with (err, roots); roots is an Array of Node objects:

Node {
  index: location in the merkle tree of this root
  size: total bytes in children of this root
  hash: hash of the children of this root (32-byte buffer)
}

var number = feed.downloaded([start], [end])

Returns total number of downloaded blocks within range. If end is not specified it will default to the total number of blocks. If start is not specified it will default to 0.

var bool = feed.has(index)

Return true if a data block is available locally. False otherwise.

var bool = feed.has(start, end)

Return true if all data blocks within a range are available locally. False otherwise.

await feed.clear(start, [end])

Clear a range of data from the local cache. Will clear the data from the bitfield and make a call to the underlying storage provider to delete the byte range the range occupies.

end defaults to start + 1.

feed.seek(byteOffset, callback)

Seek to a byte offset.

Calls the callback with (err, index, relativeOffset), where index is the data block the byteOffset is contained in and relativeOffset is the relative byte offset in the data block.

await feed.upbite([minLength])

Wait for the feed to contain at least minLength elements. If you do not provide minLength it will be set to current length + 1.

Does not download any data from peers except for a proof of the new feed length.

console.log('length is', feed.length)
feed.upbite(function () {
  console.log('length has increased', feed.length)
})

var stream = feed.createReadStream([options])

Create a readable stream of data.

Options include:

{
  start: 0, // read from this index
  end: feed.length, // read until this index
  snapshot: true, // if set to false it will upbite `end` to `feed.length` on every read
  tail: false, // sets `start` to `feed.length`
  live: false, // set to true to keep reading forever
  timeout: 0, // timeout for each data event (0 means no timeout)
  wait: true // wait for data to be downloaded
}

var stream = feed.createWriteStream()

Create a writable stream.

await feed.close()

Fully close this feed. If you loaded this feed more than once, close will be a noop until all handles have invoked it.

Calls the callback with (err) when all storage has been closed.

await feed.destroyStorage()

Closes the feed and deletes all of it's data from storage.

const {valid, invalid} = await feed.audit()

Audit all data in the feed. Will check that all current data stored matches the hashes in the merkle tree and clear the bitfield if not.

When done a report is passed to the callback that looks like this:

{
  valid: 10, // how many data blocks matches the hashes
  invalid: 0, // how many did not
}

If a block does not match the hash it is cleared from the data bitfield.

const extension = feed.registerExtension(name, handlers)

Listens on extension messages of type name on the feeds replication channels.

• handlers.encoding: The encoding to use for messages. json, binary, 'utf8'
• handlers.onmessage(message, peer): Function to invoke when a peer sends you a message for this extension type.
• handlers.onerror(err, peer): Function to invoke when a peer has sent you a mis-coded message on this extension.

You can respond to messages with extension.send(message, peer). You can also broadcast out messages to all peers with extension.broadcast(message)

feed.writable

Can we append to this feed?

Populated after ready has been emitted. Will be false before the event.

feed.readable

Can we read from this feed? After closing a feed this will be false.

Populated after ready has been emitted. Will be false before the event.

feed.key

Buffer containing the public key identifying this feed.

Populated after ready has been emitted. Will be null before the event.

feed.discoveryKey

Buffer containing a key derived from the feed.key. In contrast to feed.key this key does not allow you to verify the data but can be used to announce or look for peers that are sharing the same feed, without leaking the feed key.

Populated after ready has been emitted. Will be null before the event.

feed.length

How many blocks of data are available on this feed?

Populated after ready has been emitted. Will be 0 before the event.

feed.byteLength

How much data is available on this feed in bytes?

Populated after ready has been emitted. Will be 0 before the event.

feed.stats

Return per-peer and total upload/download counts.

The returned object is of the form:

{
  totals: {
    uploadedBytes: 100,
    uploadedBlocks: 1,
    downloadedBytes: 0,
    downloadedBlocks: 0
  },
  peers: [
    {
      uploadedBytes: 100,
      uploadedBlocks: 1,
      downloadedBytes: 0,
      downloadedBlocks: 0
    },
    ...
  ]
}

Stats will be collected by default, but this can be disabled by setting opts.stats to false.

feed.on('ready')

Emitted when the feed is ready and all properties have been populated.

feed.on('error', err)

Emitted when the feed experiences a critical error.

feed.on('download', index, data)

Emitted when a data block has been downloaded.

feed.on('upload', index, data)

Emitted when a data block is uploaded.

feed.on('append')

Emitted when the feed has been appended to (i.e. has a new length / byteLength)

feed.on('sync')

Emitted every time ALL data from 0 to feed.length has been downloaded.

feed.on('close')

Emitted when the feed has been fully closed

feed.on('peer-add', peer)

Emitted when a new peer has started replicating with the feed.

Extension messages and metabite about the remote peer isn't ready yet.

feed.on('peer-open', peer)

Emitted when a new peer has fully connected and shared it's metadata.

You should probably prefer this over peer-add.

feed.on('peer-remove', peer)

Emitted when a peer has stopped replicating with the feed.

feed.on('peer-ack', have)

Emitted when a peer has acknowledged that it loaded some of your data.

Specify ack: true in the chainstoreOpts to enable this.

You can get the have.start and have.end fields to see which portions the peer loaded. Alternately have.bitfield will contain the bitfield of the blocks that got loaded.

Potential WebRTC performance enhancement

If you are finding that WebRTC connections are not reliably made, you may get improved performance by using this:

https://github.com/webrtcHacks/adapter

E.g. In the browser code:

`