MQTT V3 Plug-in Reference

"operation"

• String
• Required
• No default value

Creates or alters a handler for MQTT messages published with the specified Persistence Topic."CreatePersistenceTopic" does the following:

• It assigns a Persistence Topic to a table in the c-tree database.
• It creates the table if it does not exist.
• It maps JSON properties to fields in the table.
• It can optionally write data to a remote database instead of a local database.
• It can optionally subscribe to another MQTT Broker to receive messages published to the specified.

  Note: A Persistence Topic in the FairCom MQTT Broker is an MQTT topic. This document uses the term “Persistence Topic” when the FairCom broker creates a handler to persist data from messages published to a specific MQTT topic. It also applies when c-tree is acting as an MQTT client subscribing to messages from another MQTT Broker.

• "AlterPersistenceTopic" does the following:
  • It removes previously -mapped properties and completely remaps them.
  • It can alter the assigned table by adding new fields.
  • It cannot change some properties. These are documented below.