[jira] [Created] (CAMEL-13077) Olingo4 Consumer appears to not work with backoffIdleThreshold

["Paul Richardson (JIRA)" <ji...@apache.org>]

Paul Richardson created CAMEL-13077:
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             Summary: Olingo4 Consumer appears to not work with backoffIdleThreshold
                 Key: CAMEL-13077
                 URL: https://issues.apache.org/jira/browse/CAMEL-13077
             Project: Camel
          Issue Type: Bug
          Components: camel-olingo4
    Affects Versions: 2.23.0, 2.22.0, 2.21.0
            Reporter: Paul Richardson


Looking into using {{backoffIdleThreshold}} for reducing the amount of polling of OData consuming. So far I cannot see how it would work for the [Olingo4Consumer|https://github.com/apache/camel/blob/master/components/camel-olingo4/camel-olingo4-component/src/main/java/org/apache/camel/component/olingo4/Olingo4Consumer.java]. Bear with me, this may get a little deep to follow!

Hierarchy: ScheduledPollConsumer > AbstractApiConsumer > Olingo4Consumer

SchedulePollConsumer maintains an [idleCounter|https://github.com/apache/camel/blob/master/camel-core/src/main/java/org/apache/camel/support/ScheduledPollConsumer.java#L61], which is incremented each time no messages are returned from polling. Once the {{idleCounter}} starts to increment then this in turn starts to increment the backoffCounter taking into account properties such as {{backoffIdleThreshold}}, resulting in delaying polling etc.

However, in order for {{idleCounter}} to increment, {{poll()}} methods must return 0 messages. Since {{Olingo4Consumer}} defers its {{result[0]}} to [ApiConsumer.getResultsProcessed()|https://github.com/apache/camel/blob/master/camel-core/src/main/java/org/apache/camel/support/component/ApiConsumerHelper.java#L85], the results must be in a form that can be handled by this static method, namely a List, an Iterable or an Array. Otherwise, the result is merely added to the Exchange and the constant '1' is returned.

Now here is the crux. OData services like to return a {{ClientEntitySet}} hence when the result is passed to {{ApiConsumerHelper}}, it is none of the expected types and ['1'|https://github.com/apache/camel/blob/master/camel-core/src/main/java/org/apache/camel/support/component/ApiConsumerHelper.java#L128] is therefore always returned. Consequently, the return value of {{poll()}} is 1 hence {{idleCounter}} is never incremented.

I hope that makes sense and if I have made a mistake then please let me know. I think the way to handle this would be to put the entities of the {{ClientEntitySet}} into the result rather than the set itself. That way ApiConsumerHelper would understand a {{Collection}} as an {{Iterable}} and return a proper value based on the size of the collection. Alternatively, if the {{ClientEntitySet}} is desired as the result then maybe {{ApiConsumerHelper}} needs to be extended in some way so as to correctly handle a return value for {{poll()}}.

Not sure which way to go on this so anxious to start a discussion.



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