Understanding MQTT Transmission Servers and Sets

Servers

The Servers tab allows you to configure a list of the MQTT Servers that MQTT Transmission should connect to.

Multiple MQTT Servers can be configured in MQTT Transmission - often times more than one will be configured to handle fail-over in redundant or geographically distributed systems. 

Sets

The Sets tab allows you to configure server sets.

Each set represents a logical grouping of MQTT servers. 

When a set is referenced by a Transmitter configuration, a single connection to one of the servers in the set will be maintained. The other servers will act as failover in the case that a connection with the first is lost.

Server sets cannot have common elements meaning that a single MQTT server cannot be in more than one set.

Examples

Single Set and Multiple Servers

In this example we have multiple servers configured that are all in the same set.

As the Transmitter configuration references the set, a single connection is made to the first available server in the set. If this server becomes unavailable, MQTT Transmission 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   and attempt to make a connection. It will continue to walk