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https://github.com/fluencelabs/js-libp2p
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60 lines
2.7 KiB
Markdown
60 lines
2.7 KiB
Markdown
# Publish Subscribe
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Publish Subscribe is also included on the stack. Currently, we have on PubSub implementation which we ship by default [libp2p-floodsub](https://github.com/libp2p/js-libp2p-floodsub), 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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## 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, all you have to do is start a libp2p node, PubSub will be enabled by default.
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```JavaScript
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series([
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(cb) => node1.once('peer:discovery', (peer) => node1.dial(peer, cb)),
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(cb) => setTimeout(cb, 500)
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], (err) => {
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if (err) { throw err }
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// Subscribe to the topic 'news'
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node1.pubsub.subscribe('news',
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(msg) => console.log(msg.from, msg.data.toString()),
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() => {
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setInterval(() => {
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// Publish the message on topic 'news'
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node2.pubsub.publish(
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'news',
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Buffer.from('Bird bird bird, bird is the word!'),
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() => {}
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)
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}, 1000)
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}
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)
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})
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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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QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82 Bird bird bird, bird is the word!
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QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82 Bird bird bird, bird is the word!
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QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82 Bird bird bird, bird is the word!
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QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82 Bird bird bird, bird is the word!
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QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82 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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