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From "Arun C Murthy (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1183) Serializable job components: Mapper, Reducer, InputFormat, OutputFormat et al
Date Fri, 06 Nov 2009 18:42:32 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1183?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12774359#action_12774359
] 

Arun C Murthy commented on MAPREDUCE-1183:
------------------------------------------

The reason I'm slightly wary about adding the factory right-away is that it is really hard
to design it in isolation without being completely biased about the JavaTaskRunner. I'm concerned
we do not understand the others enough to design the interfaces well enough... am I being
too paranoid?

> Serializable job components: Mapper, Reducer, InputFormat, OutputFormat et al
> -----------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1183
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1183
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 0.21.0
>            Reporter: Arun C Murthy
>            Assignee: Arun C Murthy
>
> Currently the Map-Reduce framework uses Configuration to pass information about the various
aspects of a job such as Mapper, Reducer, InputFormat, OutputFormat, OutputCommitter etc.
and application developers use org.apache.hadoop.mapreduce.Job.set*Class apis to set them
at job-submission time:
> {noformat}
> Job.setMapperClass(IdentityMapper.class);
> Job.setReducerClass(IdentityReducer.class);
> Job.setInputFormatClass(TextInputFormat.class);
> Job.setOutputFormatClass(TextOutputFormat.class);
> ...
> {noformat}
> The proposal is that we move to a model where end-users interact with org.apache.hadoop.mapreduce.Job
via actual objects which are then serialized by the framework:
> {noformat}
> Job.setMapper(new IdentityMapper());
> Job.setReducer(new IdentityReducer());
> Job.setInputFormat(new TextInputFormat("in"));
> Job.setOutputFormat(new TextOutputFormat("out"));
> ...
> {noformat}

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