Plugins are used to inject, delete or modify data received by the flespi devices to prepare it for further consumption and use in a variety of cases such as streaming into government-regulated systems, toll roads services, various telematics data aggregators, and the like.
The device plugins can be used to:
Store custom information in devices and use it in REST selectors. For example, add your customer id or phone number field to all devices.
Publish custom information into device telemetry.
Add custom information into JSON message representation that is published into MQTT and streams. Thus your system will be able to receive some special device attributes or operate based on this data. We are using this for implementing a tollbg plugin and stream. Another use case for this is to stream multiple devices under the same identifier.
Add custom information into JSON message representation that is stored in the flespi database. This allows you to post-process your own data with flespi analytics — build reports and trigger notifications.
Validate data received from the device and retain validated parameters value. If the message doesn't pass validation expression, the plugin won't be applied to the message at all.
Delete specified parameters from the received messages.
Add custom parsing based on the user-defined parsing scheme written using our special PVM language.
Plugins for devices define the schema of fields, how to validate field values, and what to do with them at different stages of the flespi message pipeline process. The current configuration of devices attached to the plugin can be retrieved via the REST API or by subscribing to flespi/state/gw/plugins/+/devices/+ MQTT topic.
Types of plugins
Below is the list of currently supported plugin types:
add static fields to the designated item, some of the fields can be stored as message parameters
add new message parameters as a result of evaluating expressions
remove the listed parameters from the message
execute PVM code to process the message
resolve the position address using Google reverse geocoding and add it to the message
resolve the position address using Nominatim reverse geocoding (OSM) and add it to the message. Public and private servers supported.
resolve position address using reverse Gurtam Wialon geocoding and add it to the message
resolve position coordinates using LBS Wialon geocoding and add them to the message
If you assign several plugins to a device, you may want to apply them in a specific order. Use the priority parameter in the plugin configuration to arrange the required order. The higher the number in the priority field, the earlier the plugin will apply.
Use the validate_message field in the plugin configuration to specify the validation expression that should succeed for the plugin to apply. If no validation expression is specified, the plugin will apply to all messages.
Use the timezone field in the plugin configuration to specify the correct timezone for all time/date-related operations in selectors and counters.
Read a comprehensive article on plugins here.