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From "Emmanuel Colin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (NUTCH-978) A Plugin for extracting certain element of a web page on html page parsing.
Date Wed, 09 Jan 2013 16:16:13 GMT

    [ https://issues.apache.org/jira/browse/NUTCH-978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13548624#comment-13548624
] 

Emmanuel Colin commented on NUTCH-978:
--------------------------------------

Hi Lewis, thanks for your reply. 

In fact I was suggesting that - in my opinion - the issue has been (very well) addressed by
the filter-xpath plugin described in the blog entry I pointed to. Its approach for configuration
leveraging the power of XPath queries is pretty flexible (and well described by comments in
the config file). I also tested the plugin and it works fine. 

What I would add for some more flexibility on the 'field' configuration markup is: a 'locale'
attribute to enable parsing of non English date formats; a 'fixedValue' attribute enabling
to index fixed values into Solr for better categorization when indexing specific datasets;
a 'regexPattern' and a 'regexReplace' attributes to enable some regex based postprocessing
of the data extracted (for example to remove some unwanted prefix before the interesting data).

With this, the plugin would be pretty powerful and useful to anyone wanting to extract information
from semistructured websites without writing their own plugin.
                
> A Plugin for extracting certain element of a web page on html page parsing.
> ---------------------------------------------------------------------------
>
>                 Key: NUTCH-978
>                 URL: https://issues.apache.org/jira/browse/NUTCH-978
>             Project: Nutch
>          Issue Type: New Feature
>          Components: parser
>    Affects Versions: 1.2
>         Environment: Ubuntu Linux 10.10; JDK 1.6; Netbeans 6.9
>            Reporter: Ammar Shadiq
>            Assignee: Chris A. Mattmann
>            Priority: Minor
>              Labels: gsoc2012, mentor
>             Fix For: 2.2
>
>         Attachments: app_guardian_ivory_coast_news_exmpl.png, app_screenshoot_configuration_result_anchor.png,
app_screenshoot_configuration_result.png, app_screenshoot_source_view.png, app_screenshoot_url_regex_filter.png,
for_GSoc.zip, [Nutch-GSoC-2011-Proposal]Web_Page_Scrapper_Parser_Plugin.pdf, version_alpha2.zip
>
>   Original Estimate: 1,680h
>  Remaining Estimate: 1,680h
>
> Nutch use parse-html plugin to parse web pages, it process the contents of the web page
by removing html tags and component like javascript and css and leaving the extracted text
to be stored on the index. Nutch by default doesn't have the capability to select certain
atomic element on an html page, like certain tags, certain content, some part of the page,
etc.
> A html page have a tree-like xml pattern with html tag as its branch and text as its
node. This branch and node could be extracted using XPath. XPath allowing us to select a certain
branch or node of an XML and therefore could be used to extract certain information and treat
it differently based on its content and the user requirements. Furthermore a web domain like
news website usually have a same html code structure for storing the information on its web
pages. This same html code structure could be parsed using the same XPath query and retrieve
the same content information element. All of the XPath query for selecting various content
could be stored on a XPath Configuration File.
> The purpose of nutch are for various web source, not all of the web page retrieved from
those various source have the same html code structure, thus have to be threated differently
using the correct XPath Configuration. The selection of the correct XPath configuration could
be done automatically using regex by matching the url of the web page with valid url pattern
for that xpath configuration.
> This automatic mechanism allow the user of nutch to process various web page and get
only certain information that user wants therefore making the index more accurate and its
content more flexible.
> The component for this idea have been tested on nutch 1.2 for selecting certain elements
on various news website for the purpose of document clustering. This includes a Configuration
Editor Application build using NetBeans 6.9 Application Framework. though its need a few debugging.
> http://dl.dropbox.com/u/2642087/For_GSoC/for_GSoc.zip

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