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Date: Sun, 04 Mar 2012 05:49:33 -0500
From: Gopal <absoftinc@gmail.com>
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To: common-user@hadoop.apache.org
Subject: Re: How does Hadoop compile the program written in language other
 than Java ?
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On 3/4/2012 5:44 AM, Kai Voigt wrote:
> Hi,
>
> please read http://developer.yahoo.com/hadoop/tutorial/module4.html#streaming and http://developer.yahoo.com/hadoop/tutorial/module4.html#streaming for more explanation and examples.
>
> Kai
>
> Am 04.03.2012 um 16:10 schrieb Lac Trung:
>
>> Can you give one or some examples about this, Kai ?
>> I haven't understood how Hadoop run a mapreduce program in other language :D
>>
>> Vào 02:21 Ngày 04 tháng 3 năm 2012, Kai Voigt<k@123.org>  đã viết:
>>
>>> Hi,
>>>
>>> the streaming API doesn't compile the streaming scripts.
>>>
>>> The PHP/Perl/Python/Ruby scripts you create as mapper and reducer will be
>>> called as external programs.
>>>
>>> The input key/value pairs will be send to your scripts as stdin, and the
>>> output will be collected from their stdout.
>>>
>>> So, no compilation, the scripts will just be executed.
>>>
>>> Kai
>>>
>>> Am 04.03.2012 um 15:42 schrieb Lac Trung:
>>>
>>>> Hi everyone !
>>>>
>>>> Hadoop is written in Java, so mapreduce programs are written in Java,
>>> too.
>>>> But Hadoop provides an API to MapReduce that allows you to write your map
>>>> and reduce functions in languages other than Java (ex. Python), called
>>>> Hadoop Streaming.
>>>> I read the guide of Hadoop Streaming in
>>>> here<
>>> http://www.hadoop.apache.org/common/docs/r0.15.2/streaming.html#More+usage+examples
>>>> but
>>>> I haven't seen any paragraph that write about converting language to
>>> Java.
>>>> Can anybody tell me how Hadoop compile the program written in language
>>>> other than Java.
>>>>
>>>> Thank you !
>>>> --
>>>> Lac Trung
>>> --
>>> Kai Voigt
>>> k@123.org
>>>
>>>
>>>
>>>
>>>
>>
>> -- 
>> Lạc Trung
>> 20083535
Its nothing out of ordinary.

The java routines written for your specific language  ( Jruby, Jython ) 
etc. will interpret the code and run it.

No different from how Perl or Php work.

Thanks