PreEmptive Analytics Replayer User Guide

Retry Behavior

This section provides details about how the Replayer handles envelopes that aren't successfully delivered.

Offline Response Handling and Retry

When the Replayer starts, the destination is assumed to be online. When a envelope delivery attempt results in an offline response, the destination is marked offline, and the envelope that received the response is queued in the offline queue. All further delivery attempts to this destination just move envelopes to the offline queue, to reduce traffic to the destination.

Then, periodically (every 60 seconds by default), the first envelope of the offline queue is retried. If the retry results in another offline response, the envelope is moved to the back of the offline queue, in case there are any issues caused by that particular envelope. If the retry results in a success or error response, the remainder of the queue is retried, continuing until the queue is empty or another offline response is received.

If dispatching completes and there are still envelopes in the offline queue, the Replayer will continue to attempt delivery of the offline queue periodically, until it is empty.

Error Response Handling and Retry

When a envelope delivery attempt results in an error response, the envelope that received the response is queued in the error queue and timestamped with the time it first entered the error queue. Subsequent envelopes are not affected (as with offline envelopes) as the problem is presumed to be with the envelope in particular.

Then, periodically (every 6 hours by default) the entirety of every error queue is retried. If a envelope's retry results in another error response, the envelope's timestamp is checked; if the time between this retry and the first time the envelope entered the error queue is greater than 7 days (by default), the envelope is dropped. Otherwise, the envelope is moved to the back of the error queue.

If dispatching completes and there are still envelopes in the error queue, the Replayer will continue to attempt delivery of the error queue periodically, until it is empty (either because envelopes succeed or eventually expire).



Replayer Version 1.1.0. Copyright © 2015 PreEmptive Solutions, LLC