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In explicit mode, polling works the same, but the application must acknowledge each record explicitly using one of the AcknowledgeType values. It is here that RENEW comes into play, should the application need it.

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If the RENEW request received by a broker is invalid and an error is returned, the application should use existing acknowledgement commit callback to listen for the same. Specifically, the application should set a commit response handler callback in ShareConsumer.setAcknowledgementCommitCallback(AcknowledgementCommitCallback) and handle errors, if any. This is the usual mechanism to check commit status in explicit mode and this KIP does not make any change in this code path.

Ensuring progress

There is a possibility where an application renewing a record repeatedly, could hamper progress on that share group. This will cause a head of the line blocking issue. Currently, we are not planning to put any restriction on the number of allowed renewals as that goes against the intended purpose of this KIP. But we will be logging renewal information on both the server and client side to help with debugging and discipline any misbehaving applications/share consumers part of the share group.

Compatibility, Deprecation, and Migration Plan

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