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https://issues.apache.org/jira/browse/APEXCORE-577?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15729596#comment-15729596
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Pramod Immaneni commented on APEXCORE-577:
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Why specifically limit it to client side preparation of the DAG before the
application is launched? Why not make it possible to have general hooks that
can apply even when the application is running in the different distributed
components of the application such as the containers and stram. The hooks could
be registered to be asynchronous or synchronous. The asynchronous ones could be
handled via a bus, we already have a bus called mbassador that we use today and
it could potentially be used for this. The entire functionality is akin to
something like dtrace without the dynamic part.
> Visitor API for DAG
> -------------------
>
> Key: APEXCORE-577
> URL: https://issues.apache.org/jira/browse/APEXCORE-577
> Project: Apache Apex Core
> Issue Type: Improvement
> Reporter: Tushar Gosavi
>
> Support an Visitor like api for DAG, which could be used to write plugins for
> Apex.
> change DAG interface to add a visitor
> {code}
> registerVisitor(DagVisitor visitor)
> {code}
> The DagVisitor interface
> {code}
> interface DagVisitor {
> boolean startDAG(DAG* dag);
> boolean visitOperator(OperatorMeta *ometa)
> boolean visitStream(StreamMeta *smeta);
> boolean endDAG()
> }
> {code}
> dev thread discussions
> https://lists.apache.org/thread.html/1c37e0954cee029c9de537cc35ecb35beebdf49aba17de89bd2ce9ed@%3Cdev.apex.apache.org%3E
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