2.9 KiB
Receive messages using Waku Filter
WakuFilter is a protocol that enables subscribing to messages that a peer receives. You can find Waku Filter's specifications on Vac RFC. 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.
Create a waku instance
package main
import (
"context"
"fmt"
"github.com/waku-org/go-waku/waku/v2/node"
"github.com/waku-org/go-waku/waku/v2/protocol/filter"
)
...
wakuNode, err := node.New(node.WithWakuFilter(false))
if err != nil {
fmt.Println(err)
return
}
if err := wakuNode.Start(context.Background()); err != nil {
fmt.Println(err)
return
}
...
Options
One of these options must be specified when instantiating a node supporting the waku relay protocol
WitWakuFilter(isFullNode, opts ...pubsub.Option)
- enables the waku filter protocol and receives an optional list of options to configure the protocol
Adding a peer and receiving messages
...
peerAddr, err := multiaddr.NewMultiaddr("/dns4/node-01.do-ams3.waku.test.status.im/tcp/30303/p2p/16Uiu2HAkykgaECHswi3YKJ5dMLbq2kPVCo89fcyTd38UcQD6ej5W")
if err != nil {
panic(err)
}
_, err = wakuNode.AddPeer(peerAddr, string(filter.FilterID_v20beta1))
if err != nil {
panic(err)
}
// Setting the content filter
cf := filter.ContentFilter{
Topic: "/waku/2/default-waku/proto",
ContentTopics: []string{contentTopic},
}
_, subscription, err := wakuNode.Filter().Subscribe(context.Background(), cf)
if err != nil {
panic(err)
}
for env := range subscription.Chan {
fmt.Println("Received msg:", string(value.Message().Payload))
}
...
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:
wakuNode.Filter().Subscribe(ctx, contentFilter, opts)
- subscribes to receive messages that match a specific contentFilter
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
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:
Options
filter.WithPeer(peerID)
- use an specific peer ID (which should be part of the node peerstore) to receive the messages fromfilter.WithAutomaticPeerSelection(host)
- automatically select a peer that supports filter protocol from the peerstore to receive the messages fromfilter.WithFastestPeerSelection(ctx)
- automatically select a peer based on its ping reply time