It is the string assigned to the "persistenceTopic" property.
It is the topic that FairCom MQTT Broker is listening for.
It is also the unique identifier for managing Persistence Topics, such as altering, renaming, pausing, and resuming a Persistence Topic.
If you attempt to use the "CreatePersistenceTopic" operation to create a Persistence Topic that already exists, the operation fails. c-tree logs an error to its CTSTATUS.FCS file.
If you attempt to use the "AlterPersistenceTopic" to modify a Persistence Topic that does not exist, the operation fails. c-tree logs an error to its CTSTATUS.FCS file.
A Persistence Topic can be assigned to only one table.
This is because data sent to the Persistence Topic can only be written to one table in FairCom Edge V2. In a future version, c-tree may allow one Persistence Topic to write to multiple tables.
One or more Persistence Topics may be assigned to the same table.
In other words, a table can receive data from many Persistence Topics.
You can assign multiple Persistence Topics to the same table by repeatedly sending the "CreatePersistenceTopic" operation to c-tree to associate different Persistence Topics to the same table.
Each "CreatePersistenceTopic" operation must specify a new, unique Persistence Topic.
Each "CreatePersistenceTopic" operation can map JSON properties to one or more fields that already exist in the table.
It does not have to map JSON properties to all fields.
It cannot define new fields when a table already exists. Use "AlterPersistenceTopic" to create new fields.
It cannot alter existing fields. Use "AlterPersistenceTopic" to alter existing fields. Changing field types may change how other Persistence Topics mapped to this same table store data.
If the "CreatePersistenceTopic" operation references a new field that is not in the existing table, the operation fails. c-tree logs an error to its CTSTATUS.FCS file.
Incorrect Values
When any property has an incorrect value, the entire operation fails. c-tree logs an error to its CTSTATUS.FCS file.
When the "CreatePersistenceTopic" operation fails, no data will be automatically persisted for messages containing the specified topic.
When the "AlterPersistenceTopic" operation fails, no changes to the Persistence Topic will occur. Existing settings for the Persistence Topic will continue to be in effect.
