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From "Julien Nioche (JIRA)" <j...@apache.org>
Subject [jira] [Created] (NUTCH-1918) TikaParser specifies a default namespace when generating DOM
Date Thu, 15 Jan 2015 11:02:34 GMT
Julien Nioche created NUTCH-1918:
------------------------------------

             Summary: TikaParser specifies a default namespace when generating DOM
                 Key: NUTCH-1918
                 URL: https://issues.apache.org/jira/browse/NUTCH-1918
             Project: Nutch
          Issue Type: Bug
          Components: parser
            Reporter: Julien Nioche
             Fix For: 1.10


The DOM generated by parse-tika differs from the one done by parse-html. Ideally we should
be able to use either parsers with the same XPath expressions.
This is related to [NUTCH-1592], but this time instead of being a matter of uppercases, the
problem comes from the namespace used. 
This issue has been investigated and fixed in storm-crawler [https://github.com/DigitalPebble/storm-crawler/pull/58].

Here is what Guillaume explained there :

bq. When parsing the content, Tika creates a properly formatted XHTML document: all elements
are created within the namespace XHTML.

bq. However in XPath 1.0, there's no concept of default namespace so XPath expressions such
as //BODY doesn't match anything. To make this work we should use //ns1:BODY and define a
NamespaceContext which associates ns1 with "http://www.w3.org/1999/xhtml"

bq. To keep the XPathExpressions simpler, I modified the DOMBuilder which is our SaxHandler
used to convert the SAX Events into a DOM tree to ignore a "default name space" and the ParserBolt
initializes it with the XHTML namespace. This way //BODY matches.




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