I haven't review this patch but I was about to start work on something
similar so a big +1 on the ability to filter out the page but allow
crawling of the outlinks. Also if the filter was able to be pluggable
to external inputs (like mahout) def +1 on that too
David Stuart
On 9 Jun 2010, at 06:53, "Andrzej Bialecki (JIRA)" <[email protected]>
wrote:
[ https://issues.apache.org/jira/browse/NUTCH-828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12876964#action_12876964
]
Andrzej Bialecki commented on NUTCH-828:
-----------------------------------------
First, as you point out, we cannot ignore the page because the
problem will repeat itself as we keep re-discovering it, so we have
to "poison" it with GONE - and I think it's ok to add another status
here to express that we never ever want to collect this page,
because GONE gets reset periodically.
If we run Fetcher in parsing mode then we can change this status
immediately, so no problem here. If we run ParseSegment then we can
also update this status in a similar way as we implement the
signature update, i.e. in ParseOutputFormat emit a
<pageUrl,CrawlDatum> that will switch the status of this page when
collected later on in CrawlDbReducer.
Fetch Filter
------------
Key: NUTCH-828
URL: https://issues.apache.org/jira/browse/NUTCH-828
Project: Nutch
Issue Type: New Feature
Components: fetcher
Environment: All
Reporter: Dennis Kubes
Assignee: Dennis Kubes
Fix For: 1.1
Attachments: NUTCH-828-1-20100608.patch,
NUTCH-828-2-20100608.patch
Adds a Nutch extension point for a fetch filter. The fetch filter
allows filtering content and parse data/text after it is fetched
but before it is written to segments. The fliter can return true
if content is to be written or false if it is not.
Some use cases for this filter would be topical search engines that
only want to fetch/index certain types of content, for example a
news or sports only search engine. In these types of situations
the only way to determine if content belongs to a particular set is
to fetch the page and then analyze the content. If the content
passes, meaning belongs to the set of say sports pages, then we
want to include it. If it doesn't then we want to ignore it, never
fetch that same page in the future, and ignore any urls on that
page. If content is rejected due to a fetch filter then its status
is written to the CrawlDb as gone and its content is ignored and
not written to segments. This effectively stop crawling along the
crawl path of that page and the urls from that page. An example
filter, fetch-safe, is provided that allows fetching content that
does not contain a list of bad words.
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