Cron

Definition

A private cron plugin is a user-defined logic that gets executed periodically, according to a frequency defined by the user.

Required files

As stated before, any type of plugin (particularly a private cron plugin) is composed by this file structure:

├── src
│   ├── control     
│   ├── function
│   ├── view.xml
├── LICENSE
├── README.md 
├── manifest.toml 

control

This is a script written either in Python or NodeJS. This can be thought of as a "set up" script, since it will only run once, at the moment of creating the plugin.

function

This is a script written either in Python or NodeJS. It will be executed based on the defined frequency.

view.xml

This file provides the developer the capability to build and display a form where users can input the plugin's required parameters.

The contents of this form are displayed when the cron plugin is being created.

For instance, consider a plugin requiring information from the user such as:

• The geographical location of a device.

• The execution period of the plugin.

• An Ubidots token.

Said form could look like this:

The developer can create a form displaying those fields by using the view.xml, as shown below:

<form name="formName">

    <group name="locacionGroup">
        <group name="location">
            <label name="labelLocation">Click on the map to specify a location</label>
            <map name="map" />
        </group>
    </group>

    <group name="unitsGroup">
        <group name="unitsSelect">
            <label name="labelUnits">Units format</label>
            <select
              name="units"
              placeholder="Units format"
              value="metric"
              type="single"
            >
                    <option value="metric">Metric</option>
                    <option value="imperial">Imperial</option>
            </select>
        </group>
    </group>

    <group name="freq">        
        <group name="freqInfo">
            <frequency label="Run every {field} minutes"/>
        </group>
        <label name="labelUnits" help="Please note data is updated every 10 to 20 minutes"></label>
    </group>

    <group name="ubidotsInformation">
        <group name="fieldToken">
            <label name="labelToken">Ubidots Token</label>
            <token name="token" placeholder="Select Token"/>
        </group>
    </group>
</form>

All of these parameters in the form are accessible to the function and control scripts on each of its executions within the _parameters key in the incoming JSON object.

For detailed information about the supported elements in the view.xml file, head to its dedicated section in the "Plugins development" page.

LICENSE and README.md

Refer to the "Private Plugins" page to get more information:

Private Plugins

Manifest.toml

Aside from the manifest components common to all plugin types, the following are specific to cron-type plugins:

Section	Key	Value	Description	Example
[settings]	runtime	Any Python or NodeJS valid version.	This is the environment in which the plugin will run.	runtime = "python:3.7"
[settings.cron]	interval	Any integer number, T, in the range: 1 < T < y. This value is in minutes.	Default frequency at which the plugin will be executed.	interval = 1
[settings.cron]	run_on_deploy*	true or false	Determines if the plugin will be executed immediately upon creation	run_on_deploy = false

With that in mind, a typical manifest.toml file for a private cron plugin looks like this:

manifest_version = 2.0
 
[settings] 
version = "1.0.56" 
runtime = "nodejs:10" | "python:3.7"
plugin_type = "cron" 
license_name = "MIT license" 

[settings.cron] 
interval = 1 
run_on_deploy = false

[pricing]
price = 0 

Manifest's file keys marked with a * mean that they're not mandatory and can be omitted/not set.

Naming convention

You must employ the names of all files and directories mentioned in the "required files" section, as the plugins engine specifically searches for these files and their extensions.

For instance:

• If your plugin is using Python as runtime, the scripts' names should be control.py and function.py

• If your plugin is using NodeJS as runtime, the scripts' names should be control.js and function.js

The language selected for the control and functionscripts must match with the value of theruntime key in the manifest.toml file