Node-RED provides “Flow-based programming for the Internet of Things”, we will find out what that means by diving right in.

Node-RED is already installed on your Raspberry Pis, so all you need to do is start it on the commandline:

[user@computer ~]$ node-red
Welcome to Node-RED
===================
…
1 Jan 00:00:09 - [info] Starting flows
1 Jan 00:00:09 - [info] Started flows
1 Jan 00:00:09 - [info] Server now running at http://127.0.0.1:1880/

You can now open the Node-RED interface by right-clicking on the URL in the last line and selecting “Open Link”.

The video below shows how to setup your first Node-RED flow:

Task: Try replicating the steps seen in the video.

So what did just happen there?

First we start with the blank Node-RED interface.

Then we drag the “inject” and “debug “nodes from the pool of available nodes into our flow window.

Next we connect the Nodes. That means whenever the “inject” node produces output it will go into the input of the “debug” node.

Next we start the flow…

… open the debug output…

… and trigger the inject node.

The inject node sends, via the connection we made, a message to the debug node and the debug node prints that message to the debug output window.