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https://issues.apache.org/jira/browse/APEXMALHAR-2009?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15182923#comment-15182923
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Yogi Devendra commented on APEXMALHAR-2009:
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[Yogi]
Ashwin,
Please see my replies inline:
On 5 March 2016 at 22:42, Ashwin Chandra Putta <[email protected]> wrote:
I think the concrete implementation should contain the following to allow
for the most common use cases.
1. Take any java object as input and get the bytes of the string returned
from toString method on the object.
Yes. It would allow any java object and byte[] will be derived from the
toString(). If input is byte[]; then it would be passed on without any
conversion.
2. The separator should be configurable. Null separator should also be
valid.
Implementation will allow any String separator. Default would be newline.
Even empty string will be supported.
Are you referring to no-separator case by Null separator? How about using empty
string for no-separator instead of Null to avoid any special handling?
3. Should have one time configurable file path and name.
Yes. Filepath and name will be configurable as a property.
4. Should have configurable time based and size based rotation policy.
Do you mean rotate based on whichever happens first?
Size based rotation policy will be inherited from AbstractFileOutputOperator.
For time based rotation, are you referring to write one file for X windows?
OR rotate if there is no new data for X windows?
In either case, can we say that set appropriate value X for
APPLICATION_WINDOW_COUNT for this operator?
OR should we expose another property rotationWindowCount for this?
Regards,
Ashwin.
~ Yogi
> concrete operator for writing to HDFS file
> ------------------------------------------
>
> Key: APEXMALHAR-2009
> URL: https://issues.apache.org/jira/browse/APEXMALHAR-2009
> Project: Apache Apex Malhar
> Issue Type: Task
> Reporter: Yogi Devendra
> Assignee: Yogi Devendra
>
> Currently, for writing to HDFS file we have AbstractFileOutputOperator in the
> malhar library.
> It has following abstract methods :
> 1. protected abstract String getFileName(INPUT tuple)
> 2. protected abstract byte[] getBytesForTuple(INPUT tuple)
> These methods are kept generic to give flexibility to the app developers.
> But, someone who is new to apex; would look for ready-made implementation
> instead of extending Abstract implementation.
> Thus, I am proposing to add concrete operator HDFSOutputOperator to malhar.
> Aim of this operator would be to serve the purpose of ready to use operator
> for most frequent use-cases.
> Here are my key observations on most frequent use-cases:
> ------------------------------------------------------------------------------
> 1. Writing tuples of type byte[] or String.
> 2. All tuples on a particular stream land up in the same output file.
> 3. App developer may want to add some custom tuple separator (e.g. newline
> character) between tuples.
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