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From "Tsz Wo (Nicholas), SZE (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2316) webhdfs: a complete FileSystem implementation for accessing HDFS over HTTP
Date Sat, 22 Oct 2011 03:22:32 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2316?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13133237#comment-13133237

Tsz Wo (Nicholas), SZE commented on HDFS-2316:

*Thanks everyone for looking at the webhdfs API.*  I will update the doc accordingly.  Sorry
the json types and error responses are missing.  Below are some quick responses:

> 4. case sensitivity - make the parameters lower case rather than have the filter convert
them since pathname and the user name should not be converted.

Only the parameter names are case insensitive.  The parameter values are case sensitive except
for op values and boolean values.

> Permission masks are currently octal in webhdfs and symbolic in hoop. IMO, it should
make sense to support both.

I thought about adding chmod style symbolic permission.  However, it does not make sense in
webhdfs SETPERMISSION since it only sets absolute permission (e.g. "u=rwx,go=rx", which equals
755.)  The relative permissions (e.g. "go-w") won't work.  Hoop uses ls output style for setting
permission (e.g. rwxr-xr-x).  This seems uncommon. 

> File ranges, webhdfs uses HTTP 'content-ranges' header, ...

I have implemented OPEN with offset and length parameters but decide to change it since it
is not following the http spec.  Won't it cause problems if webhdfs does follow the http spec?
> webhdfs: a complete FileSystem implementation for accessing HDFS over HTTP
> --------------------------------------------------------------------------
>                 Key: HDFS-2316
>                 URL: https://issues.apache.org/jira/browse/HDFS-2316
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: Tsz Wo (Nicholas), SZE
>         Attachments: WebHdfsAPI20111020.pdf
> We current have hftp for accessing HDFS over HTTP.  However, hftp is a read-only FileSystem
and does not provide "write" accesses.
> In HDFS-2284, we propose to have webhdfs for providing a complete FileSystem implementation
for accessing HDFS over HTTP.  The is the umbrella JIRA for the tasks.

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