Add blocks to node-red

The addition of new blocks in Ronoco is done in two parts : on the one hand the creation of the block in Node-RED allowing to define its colour, its parameters, etc. On the other hand the creation of the block in the vm allowing to define the behaviour of the block during its execution.

Ronoco - Node-RED

Go to the $HOME/catkin_ws/ronoco/ronoco-nodered folder. We will create a simple block which will be part of the common blocks. This block will have a Name (optional) and a number (not optional) as parameters.

First, it will be necessary to create the common/simple.html file as follows:

<script type="text/javascript">
    RED.nodes.registerType('simple', {
        category: 'ronoco/common',
        color: '#59c059',
        defaults: {
            name: {value: ""},
            data: {value: "", required: true}
        },
        credential:{
            name: {},
            mode: {},
            data:{}
        },
        inputs: 1,
        outputs: 1,
        icon: "icons/simple.svg",
        label: function () {
            return this.name || "simple";
        },
    });
</script>

<script type="text/html" data-template-name="simple">
    <div class="form-row">
        <label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
        <input type="text" id="node-input-name" placeholder="Name">
    </div>
    <div class="form-row">
        <label for="node-input-data"><i class="fa fa-tag"></i> Data</label>
        <input type="number" id="node-input-data" placeholder="Data">
    </div>
</script>

<script type="text/html" data-help-name="simple">
    Here we have a simple documentation
</script>

Then you need to create the common/simple.js file as follows

"use strict";

module.exports = function (RED) {
    function Simple(config) {
        RED.nodes.createNode(this, config);
        const node = this;
        node.on('input', function (msg) {
            node.send(msg);
        });
    }

    RED.nodes.registerType("simple", Simple);
}

Finally, you just have to fill in the new block in the package.json of the project

"node-red": {
    "nodes": {
        ...
        "simple": "common/simple.js"
        ...
    }
}

Simply reinstall the palette in Node-RED to see the new block

cd $HOME/.node-red
npm install $HOME/catkin_ws/src/ronoco/ronoco-nodered/

For more information on the construction of the blocks, please refer to the Node-RED documentation

Ronoco - VM

Once the block is defined in Node-RED it is still necessary to give it behaviour in the vm. The definition of behaviour in the VM happens in the $HOME/catkin_ws/src/ronoco/ronoco-vm/ronoco_vm/behaviour folder. First we will define the node behaviour. As Ronoco-vm uses the py_trees library to execute behaviour trees we must respect the interface, refer to the py_trees documentation for more information. Then just create a simple.py file in the behaviour folder.

# !/usr/bin/env python3
# -*- coding: utf-8 -*-

import logger
import py_trees

class Simple(py_trees.behaviour.Behaviour):
    def __init__(self, name, data):
        super(Simple, self).__init__(name)
        self.time = float(data)

    def setup(self, timeout):
        self.logger.debug("  %s [Simple::setup()]" % self.name)
        return True

    def initialise(self):
        self.logger.debug("  %s [Simple::initialise()]" % self.name)

    def update(self):
        self.logger.debug("  %s [Simple::update()]" % self.name)
        # Do something
        return py_trees.Status.SUCCESS #or return py_trees.Status.FAILURE

    def terminate(self, new_status):
        self.logger.debug("  %s [Simple::terminate().terminate()][%s->%s]" % (self.name, self.status, new_status))

⚠ This implementation allows you to define execution blocks. Control blocks and decorators are natively supported by py_trees. To define others, please refer to the py_trees documentation

Once the behaviour of the block is defined it is still necessary to register the block in the vm so that it can be recognised and interpreted. To do this open the behaviour.py file in the behaviour folder. Start by defining the method for building the block. This method must require the parameters name, data, child. The method should return a tuple Boolean, Object, String where Boolean is True if the block is buildable, Object contains the built block if it is buildable and String contains an error message if the object is not buildable. In sum for the simple block we have :

def simple(name, data, child):
    # Set default name if it is empty
    if name is None or name == "":
        name = "Record"
    # If data is None we can't build the bloc
    if data is None:
        return False, None, "No data"
    # Else return a Simple object
    return True, behaviour.simple.Simple(name, data), None

You still need to associate the name of the block with this function. At the end of the behaviour.py file add 'simple':simple to the types dictionary. Since the simple block is an execution block and requires data to function it is necessary to add its name to the leaf and data_node dictionaries.

⚠ In case the new block has multiple parameters it is necessary to signal this to the vm by modifying the multiple_data_nodes(node_json) method of the control.py file in the ronoco_vm folder

Ronoco-documentation

Add blocks to node-red

Ronoco - Node-RED

Ronoco - VM