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https://issues.apache.org/jira/browse/KAFKA-4713?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias J. Sax resolved KAFKA-4713.
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Resolution: Won't Fix
In AK 2.7, we introduces the new `api.Processor` with new
`api.ProcessorContext` which partially address this issue.
The old `Processor` is removed with 4.0.0 release. Thus, closing this ticket.
> Processors cannot call public methods on ProcessorContext from the init method
> ------------------------------------------------------------------------------
>
> Key: KAFKA-4713
> URL: https://issues.apache.org/jira/browse/KAFKA-4713
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Affects Versions: 0.10.0.1
> Reporter: Bruno Felaco
> Priority: Major
>
> Streams passes the ProcessorContext to the init method of a Processor on
> startup when a topic/partition is assigned. This is the only means that a
> Processor has to obtain a reference to the ProcessorContext, which is
> required if the implementation needs to be aware of the particular
> topic/partition that is being processed. However, from within the init()
> method, the only thing the implementation is allowed to do with the
> ProcessorContext is schedule periodic tasks and create/access any state
> stores. It is not allowed to get the topic, partition, or current offset.
> This severely limits what an implementation can do in init. An implementation
> may need to check with or notify another component or system that it has been
> assigned a particular topic/partition. As far as I can see, there is no other
> mechanism in Streams to allow an implementation to react to the assignment of
> topic/partition and perform any such initialization, since Streams explicitly
> controls the ConsumerRebalanceListener. The implementation would have to wait
> for the receipt of the first record to get this information which is too late
> for certain use cases.
> I propose that the following methods should be usable from the init method:
> topic()
> partition()
> and also, but not as critical:
> offset()
> timestamp()
> Alternatively, streams could allow an implementation to register a separate
> listener that would be invoked from the global ConsumerRebalanceListener
> when a topic/partition is assigned.
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