MQTT Store and Forward

The MQTT Store and Forward feature allows seamless data publish and transfer to the data consumer, MQTT broker. When the connectivity to the MQTT broker is not available, the published data items is stored. Once the connectivity is restored, the published data is forwarded to the broker. The published data items are stored in the .snf format. The .snf files follow the First-In-First-Out mechanism. That is, the files stored first at the time of network disruption are forwarded first on resuming the connectivity. The .snf files are stored in the following file path.

C:\ProgramData\Wonderware\OI-Server\$Operations Integration Supervisory Servers$\OI.GATEWAY\OI.GATEWAY\NCC\SNF\

The .snf files are automatically named in numerical order, to indicate the order in which they were stored.

The Store and Forward feature is group specific. To enable this feature for a group:

• In the Store and Forward section of the MQTT Group Parameters configuration view, select the checkbox Enable Store and Forward for this Group.

Each MQTT group has a maximum Store and Forward cache size of 4 GB. Once this limit is reached, depending on the following selection, the data is discarded or the collection of data is stopped.

• Wrap-Around Data

  The oldest data stored in the cache is discarded to allow storage space for new data.

• Stop Collecting

  If this option is selected, the system ceases to collect and store any new data. Once the connection is established again, the stored files are forwarded, which reduces the cache size, allowing storage space for new data.