MQTT Engine that provides flexibility when connecting and subscribing to specific servers.

This document will step through each of the configuration options with examples of how they might be used.

MQTT Engine Sets and Servers

The MQTT Engine Sets tab contains a list of server sets where each set represents a logical grouping of MQTT servers.

The MQTT Engine Servers tab provides a list of the MQTT Servers that MQTT Engine should connect to with each server associated with a Server Set.  Multiple servers can be associated with the same Server Set providing fail-over in redundant or geographically distributed systems. 

A single connection is made to the first available server in each set. If this server becomes unavailable, MQTT Engine will attempt to establish a connection with the next server in the set. If unsuccessful, it will continue to walk through the servers in the set until a connection can be made.

If multiple concurrent server connections are used each one should be associated with a unique Server Set. Review our Understanding Servers and Sets document for additional details.

The MQTT Engine Sets tab also contains the Primary Host configuration for the servers using the set. Review our What is Primary Host ID and how do I use it document for additional details.

MQTT Engine Servers - Filtered Namespaces

The MQTT Engine Servers (Advanced) tab contains the Filtered Namespaces configuration.

This configuration option allows for a comma separated list of namespaces that will be filtered/disabled for connections to this MQTT Server. 

This filter will apply to both the default namespaces (Elecsys, Xirgo, Sparkplug A and Sparkplug B) and any custom namespaces configured.

Example

A system with Edge devices publishing using the Sparkplug B protocol to Server A and Edge devices publishing MQTT messages to another Server B. In this instance the Access Control Lists (ACLs) on Server B may not allow for the subscriptions required by MQTT Engine for the Sparkplug B protocol. Setting the Filtered Namespaces for the MQTT Engine Server configuration for Server B to "Sparkplug B" will disable the namespace for this server connection.