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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-954) The new interface's Context objects should be interfaces
Date Tue, 15 Sep 2009 22:43:57 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12755758#action_12755758
] 

Arun C Murthy commented on MAPREDUCE-954:
-----------------------------------------

After a bit more thought I have to insist that we make {Job|TaskAttempt|TaskInputOutput|Map|Reduce}Context
interfaces. 

Let me explain.

Today each in that list extends the other, however making them abstract classes and pairing
them with concrete {Job|TaskAttempt|TaskInputOutput|Map|Reduce}ContextImpl classes results
in the necessity for MI for  problem arises since we need MI {TaskAttempt|TaskInputOutput|Map|Reduce}ContextImpl
(for e.g. TaskAttemptContextImpl should need to extend the JobContextImpl *and* be a TaskAttemptContext,
thus MI). Hence I propose we make the top-level classes interfaces.

However, {Mapper|Reduce}.Context will be abstract classes for the same reasons that Owen put
down.

----

Thoughts?

> The new interface's Context objects should be interfaces
> --------------------------------------------------------
>
>                 Key: MAPREDUCE-954
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-954
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: client
>            Reporter: Owen O'Malley
>            Assignee: Arun C Murthy
>             Fix For: 0.21.0
>
>         Attachments: MAPREDUCE-954.patch
>
>
> When I was doing HADOOP-1230, I was persuaded to make the Context objects as classes.
I think that was a serious mistake. It caused a lot of information leakage into the public
classes.

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