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http://issues.apache.org/jira/browse/NUTCH-139?page=comments#action_12360920 ]
Jerome Charron commented on NUTCH-139:
--------------------------------------
And why not using the fact that the ContentProperties object can now handles
multi-valued properties.
Each piece of code that wants to add some more reliable content about a
property simply add its own value to the property => the first value is the raw
one (for instance from the protocol level) and the more you iterate over values
of the property, the more youo have a reliable value (the last one should be
the more reliable, and is generally the interesting one, or for other reasons,
the original value may be needed, then it is simply the first value).
Yes, you loose one information with this solution: You cannot ensure that the
first value of a multi-valued property is the one from the protocol level.
But it avoid searching the same kind of information (the content-type for
instance) using many properties names ("Content-Type" for the protocol level
and "X-Nutch-Content-Type" for other levels).
We can extend the Multi-Valued Properties by adding a provider attribute while
adding a property:
public void addProperty(key, value, provider).
The provider can be one of PROTOCOL, CONTENT, OTHER, .... for instance (to be
defined)
> 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, 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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