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@mcous
Last active August 11, 2018 04:22
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ot2-pause-handler
node_modules

OT2 Pause Handler

Setup

Requirements

  • Node v8 LTS
  • npm v6
    • Once Node is installed, use npm to upgrade itself
    • npm install --global npm@latest
  • Clone or download this repository
    • git clone https://gist.github.com/3ba833f8cc7252e7cb5e84cfae4554fe.git ot2-pause-handler
    • Or Download it as ZIP

Once downloaded

# install dependencies
cd path/to/ot2-pause-handler
npm install

Usage

  1. Open the Opentrons App
  2. Upload your protocol with a robot.pause command
  3. Start the script with:
# by default, use USB-to-ethernet adapter address
node index.js

# specify a different IP (e.g. for WiFi)
node index.js "192.168.1.100"
  1. Click "Run" in the app
  2. Script will detect when protocol goes from running to paused and run its doYourThing function
// checking OT2 RPC websocket for session state changes
'use strict'
const execa = require('execa')
const WebSocket = require('ws')
const {get, uniqueId} = require('lodash')
// get host and port from command line, defaulting to USB-to-ethernet address
const argv = process.argv.slice(2)
const HOST = argv[0] || '[fd00:0:cafe:fefe::1]'
const PORT = argv[1] || 31950
// RPC message types
const TYPE_NOTIFICATION = 2
const TYPE_CONTROL = 3
// RPC notification topics
const TOPIC_SESSION = 'session'
// session states
const STATE_RUNNING = 'running'
const STATE_PAUSED = 'paused'
let ws
let sessionId = null
let previousState = null
// start
initializeRpcClient()
// YOUR CODE HERE
function doYourThing() {
console.log('Doing your thing')
// example shell command to run
execa('sleep', ['1'])
// once the shell command has finished executing, call `resume`
.then(() => call('resume'))
.catch(console.error)
}
function initializeRpcClient () {
const url = `ws://${HOST}:${PORT}`
console.log('Connecting to', url)
ws = new WebSocket(url)
// listen for RPC JSON messages on the websocket
ws.on('message', handleMessage)
}
function call (name, args = []) {
if (!sessionId) {
return console.error("Can't resume because we don't have a session")
}
console.log(`Calling method "${name}" on session ${sessionId}`)
// send a remote call of `resume` on the session object
ws.send(JSON.stringify({
$: {token: uniqueId('token')},
id: sessionId,
name,
args
}))
}
function handleMessage (data) {
const message = parseMessage(data)
// check the message metadata for the type of message
if (message.$.type === TYPE_NOTIFICATION) {
// if it's a notification, pull out the session state and handle do your
// thing if the state changed from running to paused
const {topic, payload: {state}} = getNotificationProps(message)
if (topic === TOPIC_SESSION) {
if (previousState === STATE_RUNNING && state === STATE_PAUSED) {
console.log(`Session changed from running to paused`)
doYourThing()
}
previousState = state
}
} else if (message.$.type === TYPE_CONTROL) {
// if it's the control message (initial message sent by server), grab
// the session ID from the message to make RPC calls later on
sessionId = get(message, 'root.v.session_manager.v.session.i')
if (!sessionId) {
throw new Error('Protocol must be loaded before starting this utility')
}
console.log('Listening to session', sessionId)
}
}
function parseMessage (data) {
try {
return JSON.parse(data)
} catch (e) {
console.warn('Parse error', e)
return {}
}
}
function getNotificationProps(message) {
let {topic, payload} = get(message, 'data.v', {topic: null, payload: null})
return {topic, payload: get(payload, 'v')}
}
{
"name": "ot-pause-notification-client",
"version": "1.0.0",
"lockfileVersion": 1,
"requires": true,
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"version": "1.0.0",
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},
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"version": "6.0.5",
"resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-6.0.5.tgz",
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"requires": {
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"path-key": "^2.0.1",
"semver": "^5.5.0",
"shebang-command": "^1.2.0",
"which": "^1.2.9"
}
},
"execa": {
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"resolved": "https://registry.npmjs.org/execa/-/execa-0.10.0.tgz",
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"npm-run-path": "^2.0.0",
"p-finally": "^1.0.0",
"signal-exit": "^3.0.0",
"strip-eof": "^1.0.0"
}
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"integrity": "sha1-EtSj3U5o4Lec6428hBc66A2RykQ="
},
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"resolved": "https://registry.npmjs.org/isexe/-/isexe-2.0.0.tgz",
"integrity": "sha1-6PvzdNxVb/iUehDcsFctYz8s+hA="
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}
}
{
"name": "ot2-pause-handler",
"private": true,
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "Mike Cousins <[email protected]>",
"engines": {
"node": ">=8",
"npm": ">=6"
},
"license": "Apache-2.0",
"dependencies": {
"execa": "^0.10.0",
"lodash": "^4.17.10",
"ws": "^6.0.0"
}
}
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