Designer 10.5 | webMethods Service Development Help | Working with MQTT Triggers | MQTT Trigger Requirements
 
MQTT Trigger Requirements
For an MQTT trigger to be saved in an enabled state, the following must be true:
*The MQTT connection alias that you want to use to create subscriptions and receive messages must exist.on the same Integration Server
*The trigger service that you want to use to process messages received by the trigger must exist on the same Integration Server.
*The MQTT trigger must specify a topic.
If an MQTT trigger does not meet the preceding requirements, Designer will not enable the trigger upon save. Instead, Designer prompts you to save the MQTT trigger in a disabled state.