mirror of https://github.com/status-im/go-waku.git
83 lines
3.4 KiB
Markdown
83 lines
3.4 KiB
Markdown
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Receive messages using Waku Filter
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===
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WakuFilter is a protocol that enables subscribing to messages that a peer receives. You can find Waku Filter's specifications on [Vac RFC](https://rfc.vac.dev/spec/12/). This is a more lightweight version of WakuRelay specifically designed for bandwidth restricted devices. This is due to the fact that light nodes subscribe to full-nodes and only receive the messages they desire.
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## Create a waku instance
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```go
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package main
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import (
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"context"
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"fmt"
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"github.com/status-im/go-waku/waku/v2/node"
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"github.com/status-im/go-waku/waku/v2/protocol/relay"
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)
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...
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wakuNode, err := node.New(context.Background(),
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node.WithWakuFilter(false),
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)
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if err != nil {
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fmt.Println(err)
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return
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}
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if err := wakuNode.Start(); err != nil {
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fmt.Println(err)
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return
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}
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...
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```
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### Options
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One of these options must be specified when instantiating a node supporting the waku relay protocol
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- `WithWakuRelay(opts ...pubsub.Option)` - enables the waku relay protocol and receives an optional list of pubsub options to tune or configure the gossipsub parameters. Supported options can be seen [here](https://pkg.go.dev/github.com/libp2p/go-libp2p-pubsub#Option). The recommended [parameter configuration](https://rfc.vac.dev/spec/29/) is used by default.
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- `WithWakuRelayAndMinPeers(minRelayPeersToPublish int, opts ...pubsub.Option)` - enables the waku relay protocol, specifying the minimum number of peers a topic should have to send a message. It also receives an optional list of pubsub [options](https://pkg.go.dev/github.com/libp2p/go-libp2p-pubsub#Option)
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## Adding a peer and receiving messages
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```go
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...
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peerAddr, err := multiaddr.NewMultiaddr("/dns4/node-01.do-ams3.wakuv2.test.statusim.net/tcp/30303/p2p/16Uiu2HAmPLe7Mzm8TsYUubgCAW1aJoeFScxrLj8ppHFivPo97bUZ")
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if err != nil {
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panic(err)
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}
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_, err = wakuNode.AddPeer(peerAddr, string(filter.FilterID_v20beta1))
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if err != nil {
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panic(err)
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}
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// Setting the content filter
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cf := filter.ContentFilter{
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Topic: "/waku/2/default-waku/proto",
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ContentTopics: []string{contentTopic},
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}
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_, subscription, err := wakuNode.Filter().Subscribe(context.Background(), cf)
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if err != nil {
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panic(err)
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}
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for env := range subscription.Chan {
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fmt.Println("Received msg:", string(value.Message().Payload))
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}
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...
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```
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To receive messages sent via the relay protocol, you need to subscribe to a pubsub topic. This can be done via any of these functions:
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- `wakuNode.Filter().Subscribe(ctx, contentFilter, opts)` - subscribes to receive messages that match a specific contentFilter
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This function return a `Filter` subscrition. To stop receiving messages in this channel `wakuNode.UnsubscribeByFilter(ctx, theFilter)` can be executed which will close the subscription and channel for the filter. `wakuNode.Unsubscribe` and `wakuNode.UnsubscribeFilterByID` are also available for similar purposes
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If no options are specified when subscribing to a filter node, go-waku will automatically choose the peer to subscribe to. This behaviour can be controlled via options:
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### Options
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- `filter.WithPeer(peerID)` - use an specific peer ID (which should be part of the node peerstore) to receive the messages from
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- `filter.WithAutomaticPeerSelection(host)` - automatically select a peer that supports filter protocol from the peerstore to receive the messages from
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- `filter.WithFastestPeerSelection(ctx)` - automatically select a peer based on its ping reply time
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