Guide / JavaScript /

Connecting nodes

The first thing to do is create and connect nodes. Dop is transport agnostic so is up to you decide how they will communicate. In this example, we will use WebSockets because is the easiest way to create real-time and bidirectional communication.

Assuming we already have a WebSocket connection

// Server
const { createNode } = require('dop')
const client = createNode()

function getServerEndPoints() {
    return {
        login: () => {},
        register: () => {}
    }
}

client.open(ws.send, getServerEndPoints)

The first argument of open is a function that dop will run anytime it needs to send data to the client. The second argument is an optional function that will be the entry point of the client.

// Client
const { createNode } = require('dop')
const server = createNode()
const getServerEndPoints = server.open(ws.send)

open returns the function that is been passed as second argument in the other side. If we run it, we will get what it should.

const { login, register } = await getServerEndPoints()

Also don't forget passing all the data we receive from client.

ws.on('message', msg => {
    client.message(msg)
})

This might looks very abstract but when we combine everything with a library like ws it becomes very clear and simple.

// Server
const { createNode } = require('dop')
const WebSocket = require('ws')
const wss = new WebSocket.Server({ port: 8080 })
const sum = (a, b) => a + b
const multiply = (a, b) => a * b
const getCalculator = () => ({ sum, multiply })
wss.on('connection', ws => {
    const client = createNode()
    client.open(ws.send.bind(ws), getCalculator)
    ws.on('message', client.message)
})

// Client
const ws = new WebSocket('ws://localhost:8080')
const server = createNode()
ws.on('open', async () => {
    const getCalculator = server.open(ws.send.bind(ws))
    const { sum, multiply } = await getCalculator()
    const result1 = await sum(5, 5)
    const result2 = await multiply(3, 3)
    console.log(result1, result2) // 10, 9
})
ws.on('message', server.message)

Try it yourself https://runkit.com/josema/5e11d3313a68ac001a6a524e

Or in the browser:

<script src="https://unpkg.com/dop"></script>
<script>
    const ws = new WebSocket('ws://localhost:8080')
    const server = dop.createNode()
    ws.onopen = async () => {
        const getCalculator = server.open(ws.send.bind(ws))
        const { sum, multiply } = await getCalculator()
        const result1 = await sum(5, 5)
        const result2 = await multiply(3, 3)
        alert(`${result1} ${result2}`) // 10, 9
    }
    ws.onmessage = e => server.message(e.data)
</script>

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