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http://issues.apache.org/jira/browse/NUTCH-139?page=comments#action_12361900 ]
Jerome Charron commented on NUTCH-139:
--------------------------------------
Doug,
This implementation is a multi-valued implementation:
1. The protocol headers are stored as-is.
2. Then correct values (guessed from parsers, mime-type or whatever) are added
to the metadata.
Thus, finally, for instance for content-type we can have something like this in
metadata:
key: Content-Type
values:
* text/plain; charset= ....
* text/plain
* text/html
The values are ordered: the first one is the one at protocol level, then other
values are the ones guessed by many piece of code: The idea behind is that: the
first value is the raw value, and the more you iterate over values, the more
the value is accurate (we hope).
For instance in the major parts of code the last(CONTENT_TYPE) value will be
used, but in Cache.java, the first(CONTENT-TYPE) value will be used.
> 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-139.060105.patch, NUTCH-139.Mattmann.patch.txt,
> NUTCH-139.jc.review.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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