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Run Hemingway app

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Franck Royer 2021-07-28 15:19:52 +10:00
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guides/relay-receive-send-messages.md
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@ -6,7 +6,7 @@ You can find Waku Relay's specifications on [Vac RFC](https://rfc.vac.dev/spec/1
Before starting, you need to choose a _Content Topic_ for your dApp. Before starting, you need to choose a _Content Topic_ for your dApp.
Check out the [choose a content topic guide](choose-content-topic.md) to learn more about content topics. Check out the [choose a content topic guide](choose-content-topic.md) to learn more about content topics.
For the purpose of this guide, we are using a unique content topic: `/relay-guide/1/chat/proto`. For this guide, we are using a unique content topic: `/relay-guide/1/chat/proto`.
# Installation # Installation
@ -35,14 +35,13 @@ For now, the easiest way is to connect to Status' Waku fleet:
```js ```js
import { getStatusFleetNodes } from 'js-waku'; import { getStatusFleetNodes } from 'js-waku';
const nodes = await getStatusFleetNodes(); const nodes = await getStatusFleetNodes();
await Promise.all(nodes.map((addr) => waku.dial(addr))); await Promise.all(nodes.map((addr) => waku.dial(addr)));
``` ```
# Receive messages # Receive messages
To monitor messages for your app, you need to register an observer on relay for your app's content topic: To watch messages for your app, you need to register an observer on relay for your app's content topic:
```js ```js
const processIncomingMessage = (wakuMessage) => { const processIncomingMessage = (wakuMessage) => {
@ -52,9 +51,6 @@ const processIncomingMessage = (wakuMessage) => {
waku.relay.addObserver(processIncomingMessage, ['/relay-guide/1/chat/proto']); waku.relay.addObserver(processIncomingMessage, ['/relay-guide/1/chat/proto']);
``` ```
`WakuMessage.payloadAsUtf8` is a nice helper to show UTF-8 encoding messages.
However, you will probably need more structure messages, this is covered in [use protobuf section](#use-protobuf).
# Send messages # Send messages
You are now ready to send messages. You are now ready to send messages.
@ -80,7 +76,7 @@ await waku.relay.send(wakuMessage);
Sending strings as messages in unlikely to cover your dApps needs. Sending strings as messages in unlikely to cover your dApps needs.
To include structured objects in Waku Messages, To include structured objects in Waku Messages,
it is recommended to use [protobuf](https://developers.google.com/protocol-buffers/). We recommend you use [protobuf](https://developers.google.com/protocol-buffers/).
First, let's define an object. First, let's define an object.
For this guide, we will use a simple chat message that contains a timestamp and text: For this guide, we will use a simple chat message that contains a timestamp and text:
@ -92,7 +88,7 @@ For this guide, we will use a simple chat message that contains a timestamp and
} }
``` ```
To encode and decode protobuf, you can use the [protons](https://www.npmjs.com/package/protons) package. To encode and decode protobuf payloads, you can use the [protons](https://www.npmjs.com/package/protons) package.
## Install protobuf library ## Install protobuf library
@ -122,10 +118,10 @@ You can learn about protobuf definitions here:
## Encode messages ## Encode messages
Instead of wrapping a string in a Waku Message, you need to encode the message in protobuf. Instead of wrapping an utf-8 string in a Waku Message,
The result is a byte array that can then be wrapped in a Waku Message. you are going to wrap a protobuf payload.
First, encode the message: First, encode the object:
```js ```js
const payload = proto.SimpleChatMessage.encode({ const payload = proto.SimpleChatMessage.encode({
@ -164,7 +160,7 @@ const processIncomingMessage = (wakuMessage) => {
}; };
``` ```
Same than before, you can pass add this function as an observer to Waku Relay to process incoming messages: Like before, add this callback as an observer to Waku Relay:
```js ```js
waku.relay.addObserver(processIncomingMessage, ['/relay-guide/1/chat/proto']); waku.relay.addObserver(processIncomingMessage, ['/relay-guide/1/chat/proto']);