MQTT Storage Read Transfer Object
Use the MQTT Storage Read Transfer Object to read MQTT messages that were previously stored using the MQTT Data Storage function of the MQTT plug-in.
Before configuring the transfer object, make sure that the MQTT plug-in is configured correctly and that the Enable MQTT Data Storage option is turned on. Only then can this transfer object be used.
Basic Settings
After double-clicking the transfer object, configure the following properties:
| Property | Description |
|---|---|
| Broker Connection | Select the configured MQTT broker connection from which MQTT Data Storage is to be read. |
| Topic | Specify the topic or a topic pattern for which stored messages are to be read. Wildcards are allowed. |
| Dynamic Topic | Enable this option if the topic to be read is to be specified at runtime via an input value. |
You can then further refine the output using optional include and exclude filters.
Within a filter list, an OR operator applies to each filter. A match in Include includes a record in the result set; a match in Exclude excludes it.
Filters
Filter Field
| Field | Description |
|---|---|
| Topic | The filter value is applied to the topics stored in memory. |
| Payload | The filter value is applied to the stored message contents. |
| QoS | The filter value is applied to the stored Quality of Service values. |
| Direction | The filter value is applied to the stored message direction. |
| Timestamp | The filter value is applied to the stored timestamps. |
Direction
| Direction | Description |
|---|---|
| Published | The most recent message content stored in memory on a topic was published by this instance. |
| Received | The most recent message content stored in memory on a topic was received from another source. |
Filter Type
| Type | Description |
|---|---|
| Contains | The filter value appears anywhere in the selected filter field. |
| Matches | The filter value must exactly match the content of the selected filter field. |
| Regex | The filter value is interpreted as a regular expression. |
Filter Value
| Property | Description |
|---|---|
| Value | The comparison value used to apply the configured filter. |
Timestamp Filter Value
| Local | Format |
|---|---|
| de_DE | [dd.MM.YYYY HH:mm:ss:fff] |
Behavior When No Results Are Found
Finally, specify how the transfer object should behave if no matching data is found.
| Behavior | Description |
|---|---|
| Error | The transfer object reports an error, and further execution of the flow is terminated. |
| Abort | The transfer object reports that no data could be read, and the flow continues to run. |
| Ignore | The transfer object reports successful execution, even if no data was read. |
Confirm your entries by selecting “OK” (Confirm).