Page History

Introduction

MQTT Store and Forward allows data to be buffered locally at a client when connections are down to the MQTT Server infrastructure and deliver that data when the connection is restored. This feature is critical in most applications because if we lose connection to the MQTT Server we will lose data if it is not buffered locally. When Store and Forward is enabled and the edge node detects a disconnect to the MQTT Server, tags will be stored locally in a history store. When the edge node can reconnect to the MQTT Server, it will publish any stored tags. The rate at which these stored tags are flushed from the history store is configurable to prevent any delays in the delivery of live data.

...

MQTT Transmission History Store requires the following parameters:

• Type
  • The type of History Store with options of In-Memory and Disk-Backed
  • Data stored in an In-Memory History Store will not be persisted across a module configuration change, module disable/enable, module restart or power loss. 
  • Data stored in a Disk-Backed History Store will persist across a module configuration change, module disable/enable, module restart or power loss.
• History Max Age
  
  • Maximum number of minutes to store history before dropping the data.
• Flush Quantity
  
  • The maximum number of tags to publish in a single message upon reestablishing communication.
    
  • Default 10,000
• Flush Period
  • The period to wait in milliseconds between publishes when flushing messages upon reestablishing communication.
  • Default 200

...