Using node.js

Time compressed video of Irish railway data from November 30th 2012.

update notes 2/11/2021

After many years…. I was able to get this running

• in the project folder (ie., /trains)
  • npm init
  • then do: npm install <package> for these packages:
    • request
    • xml2js
    • util
    • http
    • ws
• then just ran: node max-train1.js and started polling in train-drawing4.maxpat and the data started rolling in
• webSockets code was replace using ws library

Also using sample webSockets code from here to handle the map points: https://masteringjs.io/tutorials/node/websockets

Next steps:

I would like to update all of this in node for max – but its also nice to have an example of doing OSC communication with Max the old way.

Original documentation follows

This map is centered on Dublin. Each train is a different color and the train number gets printed next to the current position. So for example you can see P607 coming into Dublin from the South.

It gets updates every 10 seconds or so – but sometimes the trains seem to ‘jump’ so I don’t think the actual  data itself gets updated that fast.

download

https://github.com/tkzic/internet-sensors

folder: trains

files:

main Max patches

• max-train3.maxpat
• train-drawing4.maxpat

abstractions and other files

• data_recorder_list-tz.maxpat

node.js

• max-train1.js: (main server)
• bigInt.js: (Osc support)
• byteConverter.js: (Osc support)
• libOsc.js: (Osc library)
• max.html: (the web client file – runs in browser)

node.js installation

Install node.js on your computer (or a separate server). Instructions here: http://nodejs.org

In a terminal window go to the project folder ie., /internetsensors/trains

type: npm init

(just accept all the default values)

The following node packages are required. Install using npm. For example:

type: npm install request

Do the same with all these packages

instructions

node ./max-train1.js

Running the chat thing

When you connect to the node server in a web browser, for example using the following url:

http://localhost:8124

You will get a message welcoming you and asking you to enter your name. After you enter your name, Max will send you a response. Then you can enter map points using the following format:

Dublin 53.15 -6.90

The map point will be drawn on the map in the Max patch.

how does it work?

Data communication is done with OSC messages. Here’s how

• Max sends a /getTrains message to a node.js server
• The server runs an http: request to the Irish rail API
• The server parses the response data and sends back a bunch of /train name x y messages. to Max
• You can also connect to the node server from web browsers in kind of a ‘chat’ thing (using Web sockets) and enter geographical place names with lat/lon – which get pinned to the map – and Max sends back personalized thank-you notes.

Here’s what the raw data looks like:

// note: if you want to run this program on something other than localhost, then put in the ip
// address of the server here, instead of local host...

//     var socket = io.connect('http://localhost:8124');
//
       var socket = io.connect(192.168.1.10:8124');

var dSendAddress = '127.0.0.1';	// send response messages to max at this address
// do this if max is running somewhere other than the same computer as the node server
// var dSendAddress = '192.168.1.104';	// send response messages to max at this address

what’s next

• Make sure that the Max Patch loads a preset map setting by default
• put a timestamp message in the node console and Max console so we know at the end of a train list what the current time is.
• clean up  instructions 
• make a screencast do demonstrate how to use this needlessly complicated patch.