Greengrass v2 IPC IoT Core messaging limits

Question

When sending messages through the IPC IoT Core MQTT system ( https://docs.aws.amazon.com/greengrass/v2/developerguide/ipc-iot-core-mqtt.html ) , is there a limit to the number of messages queued / age of messages sent if the greengrass system is not currently able to connect to IoT?  
  
Are they the same limits as on https://docs.aws.amazon.com/general/latest/gr/iot-core.html#message-broker-limits ?   
  
Background: I'm using a greengrass component to send messages to IoT Core, and want to know if I should store / buffer data if the system is offline, or can I just let the IPC service handle sending the data when the device comes back online?

Answer

Greengrass is a normal AWS IoT Thing, so all the regular MQTT limits imposed by IoT Core do apply in the same way.  
  
Greengrass v2 has a message spooler for saving messages while offline. I'd recommend that you have a look at the Nucleus component configuration here: https://docs.aws.amazon.com/greengrass/v2/developerguide/greengrass-nucleus-component.html#greengrass-nucleus-component-configuration specifically the "spooler" section. It allows you to configure the amount of messages to keep (by bytes) and whether to keep or drop QoS 0 messages. Currently the spooler is only in-memory, so if Greengrass restarts the messages will still be lost.  
  
Cheers,  
Michael Dombrowski

Greengrass v2 IPC IoT Core messaging limits

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