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diff --git a/diy-dat.md b/diy-dat.md new file mode 100644 index 0000000..3b3263b --- /dev/null +++ b/diy-dat.md @@ -0,0 +1,73 @@ +# DIY Dat + +This document shows how to write your own compatible `dat` client using node modules. + +The three essential node modules are called [hyperdrive](https://npmjs.org/hyperdrive), [discovery-swarm](https://npmjs.org/discovery-swarm) and [level](https://npmjs.org/level). Hyperdrive does file synchronization and versioning, discovery-swarm does peer discovery over local networks and the Internet, and level provides a local LevelDB for storing metadata. More details are available in [How Dat Works](how-dat-works.md). The [dat](https://npmjs.org/dat) module itself is just some code that combines these two modules and wraps them in a command-line API. + +Here's the minimal code needed to download data from a dat: + +```js +var Swarm = require('discovery-swarm') +var Hyperdrive = require('hyperdrive') +var Level = require('level') + +// run this like: node thisfile.js 4c325f7874b4070blahblahetc +// the dat link someone sent us, we want to download the data from it +var link = new Buffer(process.argv[2], 'hex') + +// here are the default config dat uses: +// used for MDNS and also as the dns 'app name', you prob shouldnt change this +var DAT_DOMAIN = 'dat.local' +// dat will try this first and pick the first open port if its taken +var DEFAULT_LOCAL_PORT = 3282 +// we run the servers below you can use if you want or run your own +var DEFAULT_DISCOVERY = [ + 'discovery1.publicbits.org', + 'discovery2.publicbits.org' +] +var DEFAULT_BOOTSTRAP = [ + 'bootstrap1.publicbits.org:6881', + 'bootstrap2.publicbits.org:6881', + 'bootstrap3.publicbits.org:6881', + 'bootstrap4.publicbits.org:6881' +] + +var db = Level('./dat.db') +var drive = Hyperdrive(db) +var swarm = Swarm({ + id: drive.core.id, + dns: {server: DEFAULT_DISCOVERY, domain: DAT_DOMAIN}, + dht: {bootstrap: DEFAULT_BOOTSTRAP}, + stream: function () { + // this is how the swarm and hyperdrive interface + console.log('new peer stream') + return drive.createPeerStream() + } +}) + +swarm.once('listening', function () { + console.log('joining', link) + // join the swarm + swarm.join(link) + // tell hyperdrive to start downloading/uploading in ./data + var archive = drive.get(link, process.cwd() + '/data') + archive.ready(function (err) { + console.log('archive ready') + // a stream of all metadata. after retrieving each entry metadata will be cached locally + // but the first time it has to fetch it from the swarm + var metadata = archive.createEntryStream() + // start downloading all entries, or choose your own filter logic to download specific entries + // entries will be either files or directories + metadata.on('data', function (entry) { + var dl = archive.download(entry) + console.log('downloading', entry.name, dl) + + dl.on('ready', function () { + console.log('download started', entry.name, dl) + }) + }) + }) +}) + +swarm.listen(DEFAULT_LOCAL_PORT) +```
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