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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (NUTCH-139) Standard metadata property names in the ParseData metadata
Date Sat, 17 Dec 2005 04:14:37 GMT
    [ http://issues.apache.org/jira/browse/NUTCH-139?page=comments#action_12360645 ] 

Doug Cutting commented on NUTCH-139:
------------------------------------

I'm confused as to why all of the constant names have "X_nutch" in them.  I'd expect to see
something like that in their string values, but their names are already qualified by org.apache.nutch.ParseData,
no?  Also, it would be easier if these were all defined in an interface, something like MetadataNames.
 That way a class can "implement" that interface and then simply use the short names in code,
e.g. CONTENT_TYPE, AUTHOR, etc.

> Standard metadata property names in the ParseData metadata
> ----------------------------------------------------------
>
>          Key: NUTCH-139
>          URL: http://issues.apache.org/jira/browse/NUTCH-139
>      Project: Nutch
>         Type: Improvement
>   Components: fetcher
>     Versions: 0.7.1, 0.7, 0.6, 0.7.2-dev, 0.8-dev
>  Environment: Power Mac OS X 10.4, Dual Processor G5 2.0 Ghz, 1.5 GB  RAM, although bug
is independent of environment
>     Reporter: Chris A. Mattmann
>     Assignee: Chris A. Mattmann
>     Priority: Minor
>      Fix For: 0.7.2-dev, 0.8-dev, 0.7.1, 0.7, 0.6
>  Attachments: NUTCH-139.Mattmann.patch.txt
>
> Currently, people are free to name their string-based properties anything that they want,
such as having names of "Content-type", "content-TyPe", "CONTENT_TYPE" all having the same
meaning. Stefan G. I believe proposed a solution in which all property names be converted
to lower case, but in essence this really only fixes half the problem right (the case of identifying
that "CONTENT_TYPE"
> and "conTeNT_TyPE" and all the permutations are really the same). What about
> if I named it "Content     Type", or "ContentType"?
>  I propose that a way to correct this would be to create a standard set of named Strings
in the ParseData class that the protocol framework and the parsing framework could use to
identify common properties such as "Content-type", "Creator", "Language", etc.
>  The properties would be defined at the top of the ParseData class, something like:
>  public class ParseData{
>    .....
>     public static final String CONTENT_TYPE = "content-type";
>     public static final String CREATOR = "creator";
>    ....
> }
> In this fashion, users could at least know what the name of the standard properties that
they can obtain from the ParseData are, for example by making a call to ParseData.getMetadata().get(ParseData.CONTENT_TYPE)
to get the content type or a call to ParseData.getMetadata().set(ParseData.CONTENT_TYPE, "text/xml");
Of course, this wouldn't preclude users from doing what they are currently doing, it would
just provide a standard method of obtaining some of the more common, critical metadata without
pouring over the code base to figure out what they are named.
> I'll contribute a patch near the end of the this week, or beg. of next week that addresses
this issue.

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