Package org.apache.nutch.crawl

Class MimeAdaptiveFetchSchedule

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.nutch.crawl.AbstractFetchSchedule

org.apache.nutch.crawl.AdaptiveFetchSchedule

org.apache.nutch.crawl.MimeAdaptiveFetchSchedule

All Implemented Interfaces:

Configurable, FetchSchedule

public class MimeAdaptiveFetchSchedule
extends AdaptiveFetchSchedule

Extension of @see AdaptiveFetchSchedule that allows for more flexible configuration of DEC and INC factors for various MIME-types. This class can be typically used in cases where a recrawl consists of many different MIME-types. It's not very common for MIME-types other than text/html to change frequently. Using this class you can configure different factors per MIME-type so to prefer frequently changing MIME-types over others. For it to work this class relies on the Content-Type MetaData key being present in the CrawlDB. This can either be done when injecting new URL's or by adding "Content-Type" to the db.parsemeta.to.crawldb configuration setting to force MIME-types of newly discovered URL's to be added to the CrawlDB.

Author:

markus

Field Summary

Fields

Modifier and Type	Field	Description
static final String	SCHEDULE_DEC_RATE
static final String	SCHEDULE_INC_RATE
static final String	SCHEDULE_MIME_FILE

Fields inherited from class org.apache.nutch.crawl.AdaptiveFetchSchedule

DEC_RATE, INC_RATE

Fields inherited from class org.apache.nutch.crawl.AbstractFetchSchedule

defaultInterval, maxInterval

Fields inherited from interface org.apache.nutch.crawl.FetchSchedule

SECONDS_PER_DAY, STATUS_MODIFIED, STATUS_NOTMODIFIED, STATUS_UNKNOWN

Constructor Summary

Constructors

Constructor	Description
MimeAdaptiveFetchSchedule()

Method Summary

Modifier and Type	Method	Description
static void	main(String[] args)
void	setConf(Configuration conf)
CrawlDatum	setFetchSchedule(Text url, CrawlDatum datum, long prevFetchTime, long prevModifiedTime, long fetchTime, long modifiedTime, int state)	Sets the fetchInterval and fetchTime on a successfully fetched page.

Methods inherited from class org.apache.nutch.crawl.AdaptiveFetchSchedule

getCustomMaxInterval, getCustomMinInterval, getHostName

Methods inherited from class org.apache.nutch.crawl.AbstractFetchSchedule

calculateLastFetchTime, forceRefetch, initializeSchedule, setPageGoneSchedule, setPageRetrySchedule, shouldFetch

Methods inherited from class org.apache.hadoop.conf.Configured

getConf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.hadoop.conf.Configurable

getConf

Field Details

SCHEDULE_INC_RATE

public static final String SCHEDULE_INC_RATE

See Also:

• Constant Field Values

SCHEDULE_DEC_RATE

public static final String SCHEDULE_DEC_RATE

See Also:

• Constant Field Values

SCHEDULE_MIME_FILE

public static final String SCHEDULE_MIME_FILE

See Also:

• Constant Field Values

Constructor Details

MimeAdaptiveFetchSchedule

public MimeAdaptiveFetchSchedule()

Method Details

setConf

public void setConf(Configuration conf)

Specified by:

setConf in interface Configurable

Overrides:

setConf in class AdaptiveFetchSchedule

setFetchSchedule

public CrawlDatum setFetchSchedule(Text url,
 CrawlDatum datum,
 long prevFetchTime,
 long prevModifiedTime,
 long fetchTime,
 long modifiedTime,
 int state)

Description copied from class: AbstractFetchSchedule

Sets the fetchInterval and fetchTime on a successfully fetched page. NOTE: this implementation resets the retry counter - extending classes should call super.setFetchSchedule() to preserve this behavior.

Specified by:

setFetchSchedule in interface FetchSchedule

Overrides:

setFetchSchedule in class AdaptiveFetchSchedule

Parameters:

url - url of the page

datum - page description to be adjusted. NOTE: this instance, passed by reference, may be modified inside the method.

prevFetchTime - previous value of fetch time, or 0 if not available.

prevModifiedTime - previous value of modifiedTime, or 0 if not available.

fetchTime - the latest time, when the page was recently re-fetched. Most FetchSchedule implementations should update the value in @see CrawlDatum to something greater than this value.

modifiedTime - last time the content was modified. This information comes from the protocol implementations, or is set to < 0 if not available. Most FetchSchedule implementations should update the value in @see CrawlDatum to this value.

state - if FetchSchedule.STATUS_MODIFIED, then the content is considered to be "changed" before the fetchTime, if FetchSchedule.STATUS_NOTMODIFIED then the content is known to be unchanged. This information may be obtained by comparing page signatures before and after fetching. If this is set to FetchSchedule.STATUS_UNKNOWN, then it is unknown whether the page was changed; implementations are free to follow a sensible default behavior.

Returns:

adjusted page information, including all original information. NOTE: this may be a different instance than @see CrawlDatum, but implementations should make sure that it contains at least all information from @see CrawlDatum}.

main

public static void main(String[] args)
                 throws Exception

Throws:

Exception