How to start 2 node servers

p5.js Libraries
1

I am using p5js and ml5js to run a local project that tracks a person and saves images to a local folder.
For this to work I have to use https://github.com/ml5js/ml5-data-and-models-server to serve the ml models locally and start an express server to allow for file down and upload.
Currently I manually start both in the terminal

cd ml5-data-and-models-server
npm run serve

and just npm start server.js in the folder that has my server.js file.

I am hoping to find a way to automatically start both. But simply starting them via the same shell script does not work since the first server blocks the rest of the script to be run.

#!/bin/bash

echo "$(date) : start file upload server"
cd /Users/stephanschulz/Documents/javascript/alphaBlend/alphaBlend_js
npm start server.js

echo "$(date) : start ml5js server"
cd /Users/stephanschulz/Documents/javascript/ml5-data-and-models-server-source
# npm install
npm run serve

I tried these 4 solutions but was not able to make them work, probably due to missing knowledge.
https://itnext.io/4-solutions-to-run-multiple-node-js-or-npm-commands-simultaneously-9edaa6215a93

Does anyone have any advice?
Thanks a bunch.

2

Using this package.json and calling npm run start does not work. It only starts the server.js that handles my file uploading but does not doe the cd and start the ml5js model server.

Here the excerpt that I changed

  "scripts": {
      "dev": "concurrently --kill-others \"cd ml5-data-and-models-server-source && npm run serve\" \"npm run start\""
  },

Here the full package.json

{
  "//1": "describes your app and its dependencies",
  "//2": "https://docs.npmjs.com/files/package.json",
  "//3": "updating this file will download and update your packages",
  "name": "alphaBlend",
  "version": "0.0.1",
  "description": "A simple Node app built on Express, instantly up and running.",
  "main": "server.js",
  "scripts": {
      "dev": "concurrently --kill-others \"cd ml5-data-and-models-server-source && npm run serve\" \"npm run start\""
  },
  "dependencies": {
    "body-parser": "^1.19.0",
    "concurrently": "^5.3.0",
    "cors": "^2.8.5",
    "crypto": "^1.0.1",
    "express": "^4.17.1",
    "formidable": "latest",
    "mime": "^2.4.6",
    "morgan": "^1.10.0",
    "multer": "^1.4.2",
    "path": "^0.12.7"
  },
  "engines": {
    "node": "12.x"
  },
  "repository": {
    "url": "https://antimodular.com/"
  },
  "license": "MIT",
  "keywords": [
    "node",
    "express"
  ],
  "devDependencies": {
    "npm-run-all": "^4.1.5"
  }
}
3

here my unsuccessful second attempt at s shell script that I am trying to start like this without the need to cd to the project folder.
Stephan:~ stephanschulz$ sh /Users/stephanschulz/Documents/javascript/alphaBlend/alphaBlend_js/start_it.sh 

#!/bin/bash

echo "$(date) : start it"
echo $PWD
SCRIPTPATH="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
echo $SCRIPTPATH

echo "$(date) : start ml5js server"
(cd $SCRIPTPATH/ml5-data-and-models-server-source && npm run serve) & npm start $SCRIPTPATH/server.js
4

my very smart and good friend Roy worked it out, a shell script that spans 2 threads, one per server.

#!/bin/bash
trap "exit" INT TERM ERR
trap "kill 0" EXIT

echo "$(date) : start it"
echo $PWD
SCRIPTPATH="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
echo $SCRIPTPATH

echo "$(date) : start ml5js server"
#cd /Users/stephanschulz/Documents/javascript/ml5-data-and-models-server-source
cd "$SCRIPTPATH/ml5-data-and-models-server-source"
# npm install
npm run serve &
ML5_PID=$!
echo "ML5_PID: $ML5_PID\n"

echo "$(date) : start file upload server"
#cd /Users/stephanschulz/Documents/javascript/alphaBlend/alphaBlend_js/server
cd "$SCRIPTPATH/server"
npm start server.js &
SERVER_PID=$!
echo "SERVER_PID: $SERVER_PID"

wait