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https://github.com/fluencelabs/js-libp2p
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62198414b3
This PR fixes all the errors in the code snippets in the readme files contained in the examples directory and it fixes the doc/GETTING_STARTED.md file. I have also updated the old package names, e.g. `libp2p-websockets` -> `@libp2p/websockets`. Resolves #1367 and resolves #1361 Co-authored-by: saul <saul@organicdesign.nz>
118 lines
4.8 KiB
Markdown
118 lines
4.8 KiB
Markdown
# Publish Subscribe
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Publish Subscribe is also included on the stack. Currently, we have two PubSub implementation available [@libp2p/floodsub](https://github.com/libp2p/js-libp2p-floodsub) and [@chainsafe/libp2p-gossipsub](https://github.com/ChainSafe/js-libp2p-gossipsub), with many more being researched at [research-pubsub](https://github.com/libp2p/research-pubsub).
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We've seen many interesting use cases appear with this, here are some highlights:
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- [Collaborative Text Editing](https://www.youtube.com/watch?v=-kdx8rJd8rQ)
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- [IPFS PubSub (using libp2p-floodsub) for IoT](https://www.youtube.com/watch?v=qLpM5pBDGiE).
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- [Real Time distributed Applications](https://www.youtube.com/watch?v=vQrbxyDPSXg)
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## 0. Set up the example
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Before moving into the examples, you should run `npm install` and `npm run build` on the top level `js-libp2p` folder, in order to install all the dependencies needed for this example. In addition, you will need to install the example related dependencies by doing `cd examples && npm install`. Once the install finishes, you should move into the example folder with `cd pubsub`.
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## 1. Setting up a simple PubSub network on top of libp2p
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For this example, we will use MulticastDNS for automatic Peer Discovery. This example is based the previous examples found in [Discovery Mechanisms](../discovery-mechanisms). You can find the complete version at [1.js](./1.js).
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Using PubSub is super simple, you only need to provide the implementation of your choice and you are ready to go. No need for extra configuration.
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First, let's update our libp2p configuration with a pubsub implementation.
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```JavaScript
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import { createLibp2p } from 'libp2p'
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import { GossipSub } from '@chainsafe/libp2p-gossipsub'
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import { TCP } from '@libp2p/tcp'
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import { Mplex } from '@libp2p/mplex'
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import { Noise } from '@chainsafe/libp2p-noise'
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const createNode = async () => {
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const node = await createLibp2p({
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addresses: {
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listen: ['/ip4/0.0.0.0/tcp/0']
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},
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transports: [new TCP()],
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streamMuxers: [new Mplex()],
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connectionEncryption: [new Noise()],
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// we add the Pubsub module we want
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pubsub: new GossipSub({ allowPublishToZeroPeers: true })
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})
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await node.start()
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return node
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}
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```
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Once that is done, we only need to create a few libp2p nodes, connect them and everything is ready to start using pubsub.
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```JavaScript
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import { fromString as uint8ArrayFromString } from "uint8arrays/from-string";
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import { toString as uint8ArrayToString } from "uint8arrays/to-string";
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const topic = 'news'
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const [node1, node2] = await Promise.all([
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createNode(),
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createNode()
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])
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// Add node's 2 data to the PeerStore
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await node1.peerStore.addressBook.set(node2.peerId, node2.getMultiaddrs())
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await node1.dial(node2.peerId)
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node1.pubsub.addEventListener("message", (evt) => {
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console.log(`node1 received: ${uint8ArrayToString(evt.detail.data)} on topic ${evt.detail.topic}`)
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})
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await node1.pubsub.subscribe(topic)
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// Will not receive own published messages by default
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node2.pubsub.addEventListener("message", (evt) => {
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console.log(`node2 received: ${uint8ArrayToString(evt.detail.data)} on topic ${evt.detail.topic}`)
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})
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await node2.pubsub.subscribe(topic)
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// node2 publishes "news" every second
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setInterval(() => {
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node2.pubsub.publish(topic, uint8ArrayFromString('Bird bird bird, bird is the word!')).catch(err => {
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console.error(err)
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})
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}, 1000)
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```
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The output of the program should look like:
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```
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> node 1.js
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connected to QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82
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node1 received: Bird bird bird, bird is the word!
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node1 received: Bird bird bird, bird is the word!
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```
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You can change the pubsub `emitSelf` option if you want the publishing node to receive its own messages.
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```JavaScript
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new GossipSub({ allowPublishToZeroPeers: true, emitSelf: true })
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```
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The output of the program should look like:
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```
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> node 1.js
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connected to QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82
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node1 received: Bird bird bird, bird is the word!
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node2 received: Bird bird bird, bird is the word!
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node1 received: Bird bird bird, bird is the word!
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node2 received: Bird bird bird, bird is the word!
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```
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## 2. Future work
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libp2p/IPFS PubSub is enabling a whole set of Distributed Real Time applications using CRDT (Conflict-Free Replicated Data Types). It is still going through heavy research (and hacking) and we invite you to join the conversation at [research-CRDT](https://github.com/ipfs/research-CRDT). Here is a list of some of the exciting examples:
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- [PubSub Room](https://github.com/ipfs-labs/ipfs-pubsub-room)
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- [Live DB - A always in Sync DB using CRDT](https://github.com/ipfs-labs/ipfs-live-db)
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- [IIIF Annotations over IPFS, CRDT and libp2p](https://www.youtube.com/watch?v=hmAniA6g9D0&feature=youtu.be&t=10m40s)
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- [orbit.chat - p2p chat application, fully running in the browser with js-ipfs, js-libp2p and orbit-db](http://orbit.chat/)
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