iot-backend/docs/flow/README.md

# Node-RED

If you boot up our tech stack using `docker-compose` you already have a Node-RED instance running on [your local machine](http://localhost:1880/).

Node-RED is an open-source, low-code, visual programming tool based on the concept of flow-based development. The idea behind it is to make it very easy to connect APIs, hardware devices, and anything else accessible over some type of network connection.

## Core Concepts

Nodes are the important part of Node-Red. They are the building blocks when working with Node-Red. Nodes are triggered by either receiving a message object from a previous node or an external event like an MQTT event. The node processes the message or event and then passes it on to the next node.

A node can:
* Inject: Starts a flow by injecting a message or a payload.
* Change: Here you can do basic transformation or modification on the message object.
* Debug: Can be used to help developing flows by sending messages to the side bar.
* Switch: Here you can add logic (like sending the message to different nodes).
* Function: Add custom JavaScript for uses cases where simple nodes do not do the trick.

Flows are an organized sequence of nodes. Let's do the "first steps" by creating a simple flow.

## Plugins


Node-RED uses plugins. You can access the plugins in the right burger menu. We already added  plugins for InfluxDB, an aggregator/tranformer from watt to kwh and capabilites for Node-RED's own Dashboard capabilites, so you don't have to add them.

![Plugins](./docs/images/node-red-plugins.png)

Of course you can install more plugins in this section, but it's better, to add them to [package.json](../../software/flow/package.json) and build a new Docker image using the [Dockerfile](../../software/flow/Dockerfile) provided in this project. 

## First steps

For debuging you can add Node-RED's own dashboard (sure, we are going to use Grafana, later).

![Overview](./docs/images/1-overview.png)

The dashboard should be visible on the righmost menu item in Node-RED.

![Dashboard item](./docs/images/dashboard.png)

In Node-RED you can add a MQQT node to receive values from the power monitor. As we run in `docker-compose`you don't have to use the IP address of our Eclipse Mosquitto sever, but you can simply use `mosquitto` as the host nome.

![MQTT Node](./docs/images/2-mqtt-node.png)git a

To simply display the values in a gauge (or chart) you can hook it up to a gauge node.

 ![Gauge Node](./docs/images/3-gauge-node.png) 

In the dasboard section you have to create a tab. Inside this tab you have to create a group. 

![Dashboard Settings](./docs/images/4-dashboard-node.png)

The tricky part is putting the gauges in the group. This is done in the gauge's settings (not in the dashboard's settings).

![Gauge Node](./docs/images/3-gauge-node.png) 

You can view the dashboard in an (also mobile) web browser.

![Mobile view](./docs/images/5-dashboard.png)

Have a look at the flow also in [this repository](./docs/00-dashboard-example/dashboard.json).

You can also [connect to InfluxDB](./docs/node-influx.md).