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* fix: add pubsub default config (#401) License: MIT Signed-off-by: Matthias Knopp <matthias-knopp@gmx.net> * docs: add default pubsub config to README (#401) License: MIT Signed-off-by: Matthias Knopp <matthias-knopp@gmx.net> * fix: pass config to provided PubSub (#401) License: MIT Signed-off-by: Matthias Knopp <matthias-knopp@gmx.net> * docs: adapt pubsub/example for new config (#401) License: MIT Signed-off-by: Matthias Knopp <matthias-knopp@gmx.net> * Update examples/pubsub/README.md Co-Authored-By: Jacob Heun <jacobheun@gmail.com> * test: add pubsub config tests (#401) License: MIT Signed-off-by: Matthias Knopp <matthias-knopp@gmx.net>
93 lines
3.3 KiB
Markdown
93 lines
3.3 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 [libp2p-gossipsub](https://github.com/ChainSafe/gossipsub-js), 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, 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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```JavaScript
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node1.once('peer:connect', (peer) => {
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console.log('connected to %s', peer.id.toB58String())
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series([
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// node1 subscribes to "news"
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(cb) => node1.pubsub.subscribe(
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'news',
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(msg) => console.log(`node1 received: ${msg.data.toString()}`),
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cb
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),
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(cb) => setTimeout(cb, 500),
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// node2 subscribes to "news"
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(cb) => node2.pubsub.subscribe(
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'news',
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(msg) => console.log(`node2 received: ${msg.data.toString()}`),
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cb
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),
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(cb) => setTimeout(cb, 500),
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// node2 publishes "news" every second
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(cb) => {
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setInterval(() => {
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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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(err) => {
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if (err) { throw err }
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}
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)
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}, 1000)
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cb()
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},
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], (err) => {
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if (err) { throw err }
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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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connected to QmWpvkKm6qHLhoxpWrTswY6UMNWDyn8hN265Qp9ZYvgS82
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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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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 don't want the publishing node to receive its own messages.
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```JavaScript
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const defaults = {
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config: {
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peerDiscovery: {
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mdns: {
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interval: 2000,
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enabled: true
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}
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},
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pubsub: {
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enabled: true,
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emitSelf: false
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}
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}
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}
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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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