FAQ
Hi, everybody. I am writing a project in C++ and want to use the power of
MapFile class(which belongs to org.apache.hadoop.io) of hadoop. Can you
please tell me how can I write code in C++ using MapFile or there is no way
to use API org.apache.hadoop.io in c++ (libhdfs only helps with
org.apache.hadoop.fs).
Thanks in advance!

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  • Enis Soztutar at Feb 6, 2009 at 3:20 pm
    There is currently no way to read MapFiles in any language other than
    Java. You can write a JNI wrapper similar to libhdfs.
    Alternatively, you can also write the complete stack from scratch,
    however this might prove very difficult or impossible. You might want to
    check the ObjectFile/TFile specifications for which binary compatible
    reader/writers can be developed in any language :

    https://issues.apache.org/jira/browse/HADOOP-3315

    Enis

    Anh Vũ Nguyễn wrote:
    Hi, everybody. I am writing a project in C++ and want to use the power of
    MapFile class(which belongs to org.apache.hadoop.io) of hadoop. Can you
    please tell me how can I write code in C++ using MapFile or there is no way
    to use API org.apache.hadoop.io in c++ (libhdfs only helps with
    org.apache.hadoop.fs).
    Thanks in advance!
  • Anh Vũ Nguyễn at Feb 25, 2009 at 3:41 am
    Thanks for your help. I read your answer and then forgot to thank you. Sorry
    about that.
    Regards,
    Vu Nguyen.
    On 2/6/09, Enis Soztutar wrote:

    There is currently no way to read MapFiles in any language other than Java.
    You can write a JNI wrapper similar to libhdfs.
    Alternatively, you can also write the complete stack from scratch, however
    this might prove very difficult or impossible. You might want to check the
    ObjectFile/TFile specifications for which binary compatible reader/writers
    can be developed in any language :

    https://issues.apache.org/jira/browse/HADOOP-3315

    Enis

    Anh Vũ Nguyễn wrote:
    Hi, everybody. I am writing a project in C++ and want to use the power of
    MapFile class(which belongs to org.apache.hadoop.io) of hadoop. Can you
    please tell me how can I write code in C++ using MapFile or there is no
    way
    to use API org.apache.hadoop.io in c++ (libhdfs only helps with
    org.apache.hadoop.fs).
    Thanks in advance!

  • Jason hadoop at Feb 25, 2009 at 4:04 am
    You may wish to look at the documentation on hadoop pipes, which provide a
    interface for writing c++ map/reduce applications and a mechanism to pass
    key/value data to C++ from hadoop.

    The framework will read and write sequence file or mapfiles, and provide
    key/value pairs to the map function and reduce function and accept key value
    pairs from them.

    I have not personally used pipes, so I do not speak from experience, but
    from reading src/mapred/org/apache/hadoop/mapred/pipes/PipesMapRunner.java
    it is clear that standard hadoop inputs are handled and the materialized key
    and value pairs passed to the map method of the pipes job.


    On Tue, Feb 24, 2009 at 7:41 PM, Anh Vũ Nguyễn wrote:

    Thanks for your help. I read your answer and then forgot to thank you.
    Sorry
    about that.
    Regards,
    Vu Nguyen.
    On 2/6/09, Enis Soztutar wrote:

    There is currently no way to read MapFiles in any language other than Java.
    You can write a JNI wrapper similar to libhdfs.
    Alternatively, you can also write the complete stack from scratch, however
    this might prove very difficult or impossible. You might want to check the
    ObjectFile/TFile specifications for which binary compatible
    reader/writers
    can be developed in any language :

    https://issues.apache.org/jira/browse/HADOOP-3315

    Enis

    Anh Vũ Nguyễn wrote:
    Hi, everybody. I am writing a project in C++ and want to use the power
    of
    MapFile class(which belongs to org.apache.hadoop.io) of hadoop. Can you
    please tell me how can I write code in C++ using MapFile or there is no
    way
    to use API org.apache.hadoop.io in c++ (libhdfs only helps with
    org.apache.hadoop.fs).
    Thanks in advance!

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postedFeb 6, '09 at 8:26a
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