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From "Milind Bhandarkar (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-941) Enhancements to Hadoop record I/O - Part 1
Date Wed, 28 Feb 2007 21:44:51 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-941?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Milind Bhandarkar updated HADOOP-941:
-------------------------------------

    Description: 
Hadoop record I/O can be used effectively outside of Hadoop. It would increase its utility
if developers can use it without having to import hadoop classes, or having to depend on Hadoop
jars. Following changes to the current translator and runtime are proposed.

Proposed Changes:

1. Use java.lang.String as a native type for ustring (instead of Text.)
2. Provide a Buffer class as a native Java type for buffer (instead of BytesWritable), so
that later BytesWritable could be implemented as following DDL:
module org.apache.hadoop.io {
  record BytesWritable {
    buffer value;
  }
}
3. Member names in generated classes should not have prefixes 'm' before their names. In the
above example, the private member name would be 'value' not 'mvalue' as it is done now.
4. Convert getters and setters to have CamelCase. e.g. in the above example the getter will
be:
  public Buffer getValue();
5. Generate clone() methods for records in Java i.e. the generated classes should implement
Cloneable.
6. Make generated Java codes for maps and vectors use Java generics.

These are the proposed user-visible changes. Internally, the translator will be restructured
so that it is easier to plug-in translators for different targets.


  was:
Hadoop record I/O can be used effectively outside of Hadoop. It would increase its utility
if developers can use it without having to import hadoop classes, or having to depend on Hadoop
jars. Following changes to the current translator and runtime are proposed.

Proposed Changes:

1. Use java.lang.String as a native type for ustring (instead of Text.)
2. Provide a Buffer class as a native Java type for buffer (instead of BytesWritable), so
that later BytesWritable could be implemented as following DDL:
module org.apache.hadoop.io {
  record BytesWritable {
    buffer value;
  }
}
3. Member names in generated classes should not have prefixes 'm' before their names. In the
above example, the private member name would be 'value' not 'mvalue' as it is done now.
4. Convert getters and setters to have CamelCase. e.g. in the above example the getter will
be:
  public Buffer getValue();
5. Provide a 'swiggable' C binding, so that processing the generated C code with swig allows
it to be used in scripting languages such as Python and Perl.
6. The default --language="java" target would generate class code for records that would not
have Hadoop dependency on WritableComparable interface, but instead would have "implements
Record, Comparable". (i.e. It will not have write() and readFields() methods.) An additional
option "--writable" will need to be specified on rcc commandline to generate classes that
"implements Record, WritableComparable".
7. Optimize generated write() and readFields() methods, so that they do not have to create
BinaryOutputArchive or BinaryInputArchive every time these methods are called on a record.
8. Implement ByteInStream and ByteOutStream for C++ runtime, as they will be needed for using
Hadoop Record I/O with forthcoming C++ MapReduce framework (currently, only FileStreams are
provided.)
9. Generate clone() methods for records in Java i.e. the generated classes should implement
Cloneable.
10. As part of Hadoop build process, produce a tar bundle for Record I/O alone. This tar bundle
will contain the translator classes and ant task (lib/rcc.jar), translator script (bin/rcc),
Java runtime (recordio.jar) that includes org.apache.hadoop.record.*, sources for the java
runtime (src/java), and c/c++ runtime sources with Makefiles (src/c++, src/c).
11. Make generated Java codes for maps and vectors use Java generics.

These are the proposed user-visible changes. Internally, the translator will be restructured
so that it is easier to plug-in translators for different targets.


        Summary: Enhancements to Hadoop record I/O - Part 1  (was: Make Hadoop Record I/O
Easier to use outside Hadoop)

Split the issue of making record I/O usable outside Hadoop into a separate issue. Will pull
the current patch, and upload a new patch.

> Enhancements to Hadoop record I/O - Part 1
> ------------------------------------------
>
>                 Key: HADOOP-941
>                 URL: https://issues.apache.org/jira/browse/HADOOP-941
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: record
>    Affects Versions: 0.10.1
>         Environment: All
>            Reporter: Milind Bhandarkar
>         Assigned To: Milind Bhandarkar
>
> Hadoop record I/O can be used effectively outside of Hadoop. It would increase its utility
if developers can use it without having to import hadoop classes, or having to depend on Hadoop
jars. Following changes to the current translator and runtime are proposed.
> Proposed Changes:
> 1. Use java.lang.String as a native type for ustring (instead of Text.)
> 2. Provide a Buffer class as a native Java type for buffer (instead of BytesWritable),
so that later BytesWritable could be implemented as following DDL:
> module org.apache.hadoop.io {
>   record BytesWritable {
>     buffer value;
>   }
> }
> 3. Member names in generated classes should not have prefixes 'm' before their names.
In the above example, the private member name would be 'value' not 'mvalue' as it is done
now.
> 4. Convert getters and setters to have CamelCase. e.g. in the above example the getter
will be:
>   public Buffer getValue();
> 5. Generate clone() methods for records in Java i.e. the generated classes should implement
Cloneable.
> 6. Make generated Java codes for maps and vectors use Java generics.
> These are the proposed user-visible changes. Internally, the translator will be restructured
so that it is easier to plug-in translators for different targets.

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