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https://issues.apache.org/jira/browse/HADOOP-6223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12751154#action_12751154
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Sanjay Radia commented on HADOOP-6223:
--------------------------------------
Migration strategy:
Two options here:
# Transition by delegating from FileSystem to the new AbstractFileSystem
(possibly over one more more releases)
** Add FileContext; FileContext calls FileSystem
** Deprecate FileSystem
** Add AbstractFileSystem
** Migrate each FS-impl to AbstractFileSystem and use a FileSystem delegator to
delegate FileSystem calls to AbstractFileSystem so that AFS-impl is called.
This step may occur over one or more releases.
** Change FileContext to call AbstractFileSystem
** Remove FileSystem (say after 1 or 2 releases)
# Transition by delegating from AbstractFileSystem to the new FileSystem
(possibly over one more more releases)
** Add FileContext and AbstractFileSystem; FileContext calls AbsrtactFileSystem
** AbstractFileSystem delegates to FileSystem for each AFS-impl that has not
yet been implemented
** Migrate each FS-Impl to AbstractFileSystem -the delegator will no longer
call FS-Impl, instead AFS_impl will be called directly. This step may occur
over one or more releases.
** Remove FileSystem (say after 1 or 2 releases)
Originally I was planning to use option 1 and hence my patch for FileContext
calls FileSystem.
I am seriously considering going with option 2.
> New improved FileSystem interface for those implementing new files systems.
> ---------------------------------------------------------------------------
>
> Key: HADOOP-6223
> URL: https://issues.apache.org/jira/browse/HADOOP-6223
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Sanjay Radia
> Assignee: Sanjay Radia
>
> The FileContext API (HADOOP-4952) provides an improved interface for the
> application writer.
> This lets us simplify the FileSystem API since it will no longer need to deal
> with notions of default filesystem [ / ], wd, and config
> defaults for blocksize, replication factor etc. Further it will not need the
> many overloaded methods for create() and open() since
> the FileContext API provides that convenience.
> The FileSystem API can be simplified and can now be restricted to those
> implementing new file systems.
> This jira proposes that we create new file system API, and deprecate
> FileSystem API after a few releases.
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