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dat-node
dat-node is a high-level module for building Dat applications on the file system.
For a lower-level API for building your own applications, use the Dat SDK which works in Node and the Web
Compatibility
Note: Version 4 of dat-node is not compatible with earlier versions (3.5.15
and below).
Dat Project Documentation & Resources
- dat project Docs
- dat protocol
- Chat on Gitter or #dat on IRC
Features
- High-level glue for common dat:// and hyperdrive modules.
- Sane defaults and consistent management of storage & secret keys across applications, using dat-storage.
- Easily connect to the dat:// network with holepunching, using hyperswarm
- Import files from the file system, using mirror-folder
- Serve dats over http with hyperdrive-http
- Access APIs to lower level modules with a single
require!
Browser Support
Many of our dependencies work in the browser, but dat-node is tailored for file system applications. See dat-sdk if you want to build browser-friendly applications.
Example
To send files via dat:
- Tell dat-node where the files are.
- Import the files.
- Share the files on the dat network! (And share the link)
var Dat = require('dat-node')
// 1. My files are in /joe/cat-pic-analysis
Dat('/joe/cat-pic-analysis', function (err, dat) {
if (err) throw err
// 2. Import the files
dat.importFiles()
// 3. Share the files on the network!
dat.joinNetwork()
// (And share the link)
console.log('My Dat link is: dat://' + dat.key.toString('hex'))
})
These files are now available to share over the dat network via the key printed in the console.
To download the files, you can make another dat-node instance in a different folder. This time we also have three steps:
- Tell dat where I want to download the files.
- Tell dat what the link is.
- Join the network and download!
var Dat = require('dat-node')
// 1. Tell Dat where to download the files
Dat('/download/cat-analysis', {
// 2. Tell Dat what link I want
key: '<dat-key>' // (a 64 character hash from above)
}, function (err, dat) {
if (err) throw err
// 3. Join the network & download (files are automatically downloaded)
dat.joinNetwork()
})
That's it! By default, all files are automatically downloaded when you connect to the other users.
Dig into more use cases below and please let us know if you have questions! You can open a new issue or talk to nice humans in our chat room.
Example Applications
- CLI: We use dat-node in the dat CLI.
- Desktop: The Dat Desktop application manages multiple dat-node instances via dat-worker.
- See the examples folder for a minimal share + download usage.
- And more! Let us know if you have a neat dat-node application to add here.
Usage
All dat-node applications have a similar structure around three main elements:
- Storage - where the files and metadata are stored.
- Network - connecting to other users to upload or download data.
- Adding Files - adding files from the file system to the hyperdrive archive.
We'll go through what these are for and a few of the common usages of each element.
Storage
Every dat archive has storage, this is the required first argument for dat-node. By default, we use dat-storage which stores the secret key in ~/.dat/ and the rest of the data in dir/.dat. Other common options are:
- Persistent storage: Stored files in
/my-dirand metadata inmy-dir/.datby passing/my-diras the first argument. - Temporary Storage: Use the
temp: trueoption to keep metadata stored in memory.
// Permanent Storage
Dat('/my-dir', function (err, dat) {
// Do Dat Stuff
})
// Temporary Storage
Dat('/my-dir', {temp: true}, function (err, dat) {
// Do Dat Stuff
})
Both of these will import files from /my-dir when doing dat.importFiles() but only the first will make a .dat folder and keep the metadata on disk.
The storage argument can also be passed through to hyperdrive for more advanced storage use cases.
Network
Dat is all about the network! You'll almost always want to join the network right after you create your Dat:
Dat('/my-dir', function (err, dat) {
dat.joinNetwork()
dat.network.on('connection', function () {
console.log('I connected to someone!')
})
})
Downloading Files
Remember, if you are downloading - metadata and file downloads will happen automatically once you join the network!
dat runs on a peer to peer network, sometimes there may not be anyone online for a particular key. You can make your application more user friendly by using the callback in joinNetwork:
// Downloading <key> with joinNetwork callback
Dat('/my-dir', {key: '<key>'}, function (err, dat) {
dat.joinNetwork(function (err) {
if (err) throw err
// After the first round of network checks, the callback is called
// If no one is online, you can exit and let the user know.
if (!dat.network.connected || !dat.network.connecting) {
console.error('No users currently online for that key.')
process.exit(1)
}
})
})
Download on Demand
If you want to control what files and metadata are downloaded, you can use the sparse option:
// Downloading <key> with sparse option
Dat('/my-dir', {key: '<key>', sparse: true}, function (err, dat) {
dat.joinNetwork()
// Manually download files via the hyperdrive API:
dat.archive.readFile('/cat-locations.txt', function (err, content) {
console.log(content) // prints cat-locations.txt file!
})
})
Dat will only download metadata and content for the parts you request with sparse mode!
Importing Files
There are many ways to get files imported into an archive! Dat node provides a few basic methods. If you need more advanced imports, you can use the archive.createWriteStream() methods directly.
By default, just call dat.importFiles() to import from the directory you initialized with. You can watch that folder for changes by setting the watch option:
Dat('/my-data', function (err, dat) {
if (err) throw err
var progress = dat.importFiles({watch: true}) // with watch: true, there is no callback
progress.on('put', function (src, dest) {
console.log('Importing ', src.name, ' into archive')
})
})
You can also import from another directory:
Dat('/my-data', function (err, dat) {
if (err) throw err
dat.importFiles('/another-dir', function (err) {
console.log('done importing another-dir')
})
})
That covers some of the common use cases, let us know if there are more to add! Keep reading for the full API docs.
API
Dat(dir|storage, [opts], callback(err, dat))
Initialize a Dat Archive in dir. If there is an existing Dat Archive, the archive will be resumed.
Storage
dir(Default) - Use dat-storage insidedir. This stores files as files, sleep files inside.dat, and the secret key in the user's home directory.dirwithopts.latest: false- Store as SLEEP files, including storing the content as acontent.datafile. This is useful for storing all history in a single flat file.dirwithopts.temp: true- Store everything in memory (including files).storagefunction - pass a custom storage function along to hyperdrive, see dat-storage for an example.
Most options are passed directly to the module you're using (e.g. dat.importFiles(opts). However, there are also some initial opts can include:
opts = {
key: '<dat-key>', // existing key to create archive with or resume
temp: false, // Use random-access-memory as the storage.
// Hyperdrive options
sparse: false // download only files you request
}
The callback, cb(err, dat), includes a dat object that has the following properties:
dat.key: key of the dat (this will be set later for non-live archives)dat.archive: Hyperdrive archive instance.dat.path: Path of the Dat Archivedat.live:archive.livedat.writable: Is thearchivewritable?dat.resumed:trueif the archive was resumed from an existing databasedat.options: All options passed to Dat and the other submodules
Module Interfaces
dat-node provides an easy interface to common Dat modules for the created Dat Archive on the dat object provided in the callback:
var network = dat.joinNetwork([opts], [cb])
Join the network to start transferring data for dat.key, using discovery-swarm. You can also use dat.join([opts], [cb]).
If you specify cb, it will be called when the first round of discovery has completed. This is helpful to check immediately if peers are available and if not fail gracefully, more similar to http requests.
Returns a network object with properties:
network.connected- number of peers connectednetwork.on('listening')- emitted with network is listeningnetwork.on('connection', connection, info)- Emitted when you connect to another peer. Info is an object that contains info about the connection
Network Options
opts are passed to discovery-swarm, which can include:
opts = {
upload: true, // announce and upload data to other peers
download: true, // download data from other peers
port: 3282, // port for discovery swarm
utp: true, // use utp in discovery swarm
tcp: true // use tcp in discovery swarm
}
//Defaults from datland-swarm-defaults can also be overwritten:
opts = {
dns: {
server: // DNS server
domain: // DNS domain
}
dht: {
bootstrap: // distributed hash table bootstrapping nodes
}
}
Returns a discovery-swarm instance.
dat.leaveNetwork() or dat.leave()
Leaves the network for the archive.
var importer = dat.importFiles([src], [opts], [cb])
Archive must be writable to import.
Import files to your Dat Archive from the directory using mirror-folder.
src- By default, files will be imported from the folder where the archive was initiated. Import files from another directory by specifyingsrc.opts- options passed to mirror-folder (see below).cb- called when import is finished.
Returns a importer object with properties:
importer.on('error', err)importer.on('put', src, dest)- file put started.src.liveis true if file was added by file watch event.importer.on('put-data', chunk)- chunk of file addedimporter.on('put-end', src, dest)- end of file write streamimporter.on('del', dest)- file deleted from destimporter.on('end')- Emits when mirror is done (not emitted in watch mode)- If
opts.countis true:importer.on('count', {files, bytes})- Emitted after initial scan of src directory. See import progress section for details.importer.countwill be{files, bytes}to import after initial scan.importer.putDonewill track{files, bytes}for imported files.
Importer Options
Options include:
var opts = {
count: true, // do an initial dry run import for rendering progress
ignoreHidden: true, // ignore hidden files (if false, .dat will still be ignored)
ignoreDirs: true, // do not import directories (hyperdrive does not need them and it pollutes metadata)
useDatIgnore: true, // ignore entries in the `.datignore` file from import dir target.
ignore: // (see below for default info) anymatch expression to ignore files
watch: false, // watch files for changes & import on change (archive must be live)
}
Ignoring Files
You can use a .datignore file in the imported directory, src, to ignore any the user specifies. This is done by default.
dat-node uses dat-ignore to provide a default ignore option, ignoring the .dat folder and all hidden files or directories. Use opts.ignoreHidden = false to import hidden files or folders, except the .dat directory.
It's important that the .dat folder is not imported because it contains a private key that allows the owner to write to the archive.
var stats = dat.trackStats()
stats.on('update')
Emitted when archive stats are updated. Get new stats with stats.get().
var st = stats.get()
dat.trackStats() adds a stats object to dat. Get general archive stats for the latest version:
{
files: 12,
byteLength: 1234,
length: 4, // number of blocks for latest files
version: 6, // archive.version for these stats
downloaded: 4 // number of downloaded blocks for latest
}
stats.network
Get upload and download speeds: stats.network.uploadSpeed or stats.network.downloadSpeed. Transfer speeds are tracked using hyperdrive-network-speed.
var peers = stats.peers
peers.total- total number of connected peerspeers.complete- connected peers with all the content data
var server = dat.serveHttp(opts)
Serve files over http via hyperdrive-http. Returns a node http server instance.
opts = {
port: 8080, // http port
live: true, // live update directory index listing
footer: 'Served via Dat.', // Set a footer for the index listing
exposeHeaders: false // expose dat key in headers
}
dat.pause()
Pause all upload & downloads. Currently, this is the same as dat.leaveNetwork(), which leaves the network and destroys the swarm. Discovery will happen again on resume().
dat.resume()
Resume network activity. Current, this is the same as dat.joinNetwork().
dat.close(cb)
Stops replication and closes all the things opened for dat-node, including:
dat.archive.close(cb)dat.network.close(cb)dat.importer.destroy()(file watcher)
License
MIT