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This tutorial describes how to connect MQTT Engine or MQTT Transmission to Amazon Web Services (AWS) IoT Core. With regard to MQTT Engine,

Warning
AWS IoT does not support guaranteed in order delivery of QoS 0 messages

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which is not all that uncommon among horizontally scalable/clustered MQTT Servers.

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When connecting with MQTT Engine, you will need to apply a custom configuration property that allows 're-ordering' of messages that arrive out of order

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Warning
AWS IoT Core supports messages with a maximum message length of 128KB.

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Leave all other fields blank and submit the configuration. If everything was set up properly, the 'Status' should show 'Connected' when complete.

Warning
For MQTT Engine, you must also set the 'reordering timeout' due to timing issues related to IoT Core message delivery.

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CustomProperties CustomProperties

For MQTT Engine, you must also set the 'reordering timeout' due to timing issues related to IoT Core message delivery. To do this, set the Custom Properties on the MQTT Engine General tab to: { "reorderingTimeout" : 3000 } as shown below and save the changes. This will allow MQTT Engine to buffer messages and reorder them should they be delivered out of order within a 3 second window. Generally 3 seconds seems to be plenty of time for the reordering with AWS IoT Core.

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