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An AEP Engine replicates sent and received sequence numbers in its entire cluster as part of the application's overall HA state. Consequently, when an application fails over to a backup or is restarted it will remember the last message seen from senders sending to it and can filter duplicates on behalf of the application. When an application's state is wiped or reinitialized it will restart its sending stream sequence to 1 which alerts downstream applications not to consider its newly lowered sequence numbers as duplicates.

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Enabling/Disabling Sequence Numbers

Solicited Sends

By default, an AEP engine is configured to set sequence numbers for messages sent via for solicited sends. Whether sequence numbers are set in messages sent via solicited sends is controlled via the setOutboundSequenceNumbers app configuration parameter. For example, the following disables setting sequence numbers in messages sent via solicited sends.

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