de.pangaea.metadataportal.harvester

Class OAIHarvesterBase

java.lang.Object

de.pangaea.metadataportal.harvester.Harvester

de.pangaea.metadataportal.harvester.OAIHarvesterBase

Direct Known Subclasses:

OAIHarvester, OAIStaticRepositoryHarvester

public abstract class OAIHarvesterBase
extends Harvester

Abstract base class for OAI harvesting support in panFMP. Use one of the subclasses for harvesting OAI-PMH or OAI Static Repositories.

This harvester supports the following additional harvester properties:

• setSpec: OAI set to harvest (default: none)
• retryCount: how often retry on HTTP errors? (default: 5)
• retryAfterSeconds: time between retries in seconds (default: 60)
• timeoutAfterSeconds: HTTP Timeout for harvesting in seconds
• metadataPrefix: OAI metadata prefix to harvest
• identifierPrefix: prepend all identifiers returned by OAI with this string
• ignoreDatestamps: does full harvesting, while ignoring all datestamps. They are saved, but ignored, if invalid.
• deleteMissingDocuments: remove documents after harvesting that were deleted from source (maybe a heavy operation). The harvester only does this on full (not on incremental harvesting). (default: true)

Author:

Uwe Schindler

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_RETRY_COUNT
static int	DEFAULT_RETRY_TIME
static int	DEFAULT_TIMEOUT
protected boolean	deleteMissingDocuments If enabled, on any kind of full harvesting it will track all valid identifiers and delete all of them not seen in index.
protected boolean	filterIncomingSets The harvester should filter incoming documents according to its set metadata.
protected String	identifierPrefix prepend all identifiers returned by OAI with this string
protected boolean	ignoreDatestamps If enabled, does full harvesting, while ignoring all datestamps (default is false).
protected String	metadataPrefix the used metadata prefix from the configuration
static String	OAI_NS
static String	OAI_STATICREPOSITORY_NS
protected int	retryCount the retryCount from configuration
protected int	retryTime the retryTime from configuration
protected Set<String>	sets the sets to harvest from the configuration, null to harvest all
protected int	timeout the timeout from configuration

Fields inherited from class de.pangaea.metadataportal.harvester.Harvester

fromDateReference, harvestCount, HARVESTER_METADATA_FIELD_LAST_HARVESTED, harvestMessageStep, iconfig, log, processor

Constructor Summary

Constructors

Constructor and Description
OAIHarvesterBase(HarvesterConfig iconfig)

Method Summary

Modifier and Type	Method and Description
void	addDocument(MetadataDocument mdoc) Adds a document to the Harvester.processor working in the background.
protected void	cancelMissingDocumentDelete() Disable the property "deleteMissingDocuments" for this instance.
void	close(boolean cleanShutdown) Closes harvester.
MetadataDocument	createMetadataDocumentInstance() Creates an instance of MetadataDocument and initializes it with the harvester config.
protected boolean	doParse(Supplier<ExtendedDigester> digSupplier, String url, AtomicReference<Instant> checkModifiedDate) Harvests a URL using the suplied digester.
protected void	enableMissingDocumentDelete() Enable unseen document deletes.
protected void	enumerateValidHarvesterPropertyNames(Set<String> props) This method is used by subclasses to enumerate all available harvester properties that are implemented by them.
protected EntityResolver	getEntityResolver(EntityResolver parent) Returns an EntityResolver that resolves all HTTP-URLS using getInputSource(java.net.URL, java.util.concurrent.atomic.AtomicReference<java.time.Instant>).
protected InputSource	getInputSource(URL url, AtomicReference<Instant> checkModifiedDate) Returns a SAX InputSource for retrieving stream data of an URL.
protected org.apache.commons.digester.ObjectCreationFactory	getMetadataDocumentFactory() Returns a factory for creating the MetadataDocuments in Digester code (using FactoryCreateRule).
void	open(ElasticsearchConnection es, String targetIndex) Opens harvester for harvesting documents described by the given HarvesterConfig.
protected abstract void	recreateDigester() Recreates all digesters that are used by parsing the OAI XML.
protected void	reset() Resets the internal variables.

Methods inherited from class de.pangaea.metadataportal.harvester.Harvester

deleteDocument, finishReindex, getValidHarvesterPropertyNames, harvest, isAllIndexes, isClosed, isDocumentOutdated, main, prepareReindex, runHarvester, runHarvester, setHarvestingDateReference, setValidIdentifiers

Methods inherited from class java.lang.Object

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

Field Detail

OAI_NS

public static final String OAI_NS

See Also:

Constant Field Values

OAI_STATICREPOSITORY_NS

public static final String OAI_STATICREPOSITORY_NS

See Also:

Constant Field Values

DEFAULT_RETRY_TIME

public static final int DEFAULT_RETRY_TIME

See Also:

Constant Field Values

DEFAULT_RETRY_COUNT

public static final int DEFAULT_RETRY_COUNT

See Also:

Constant Field Values

DEFAULT_TIMEOUT

public static final int DEFAULT_TIMEOUT

See Also:

Constant Field Values

metadataPrefix

protected final String metadataPrefix

the used metadata prefix from the configuration

identifierPrefix

protected final String identifierPrefix

prepend all identifiers returned by OAI with this string

sets

protected final Set<String> sets

the sets to harvest from the configuration, null to harvest all

retryCount

protected final int retryCount

the retryCount from configuration

retryTime

protected final int retryTime

the retryTime from configuration

timeout

protected final int timeout

the timeout from configuration

ignoreDatestamps

protected final boolean ignoreDatestamps

If enabled, does full harvesting, while ignoring all datestamps (default is false). They are saved, but ignored, if invalid.

deleteMissingDocuments

protected final boolean deleteMissingDocuments

If enabled, on any kind of full harvesting it will track all valid identifiers and delete all of them not seen in index.

filterIncomingSets

protected boolean filterIncomingSets

The harvester should filter incoming documents according to its set metadata. Should be disabled for OAI-PMH protocol with only one set. Default is true.

Constructor Detail

OAIHarvesterBase

public OAIHarvesterBase(HarvesterConfig iconfig)

Method Detail

open

public void open(ElasticsearchConnection es,
                 String targetIndex)
          throws Exception

Description copied from class: Harvester

Opens harvester for harvesting documents described by the given HarvesterConfig. Opens Harvester.processor for usage in Harvester.harvest() method.

Overrides:

open in class Harvester

Throws:

Exception - if an exception occurs during opening (various types of exceptions can be thrown).

addDocument

public void addDocument(MetadataDocument mdoc)
                 throws Exception

Description copied from class: Harvester

Adds a document to the Harvester.processor working in the background.

Overrides:

addDocument in class Harvester

Throws:

BackgroundFailure - if an error occurred in background thread. Exceptions can be thrown asynchronous and may not affect the currect document. The real exception is thrown again in Harvester.close(boolean).

Exception

createMetadataDocumentInstance

public MetadataDocument createMetadataDocumentInstance()

Description copied from class: Harvester

Creates an instance of MetadataDocument and initializes it with the harvester config. This method should be overwritten, if a harvester uses another class.

Overrides:

createMetadataDocumentInstance in class Harvester

getMetadataDocumentFactory

protected org.apache.commons.digester.ObjectCreationFactory getMetadataDocumentFactory()

Returns a factory for creating the MetadataDocuments in Digester code (using FactoryCreateRule).

See Also:

createMetadataDocumentInstance()

recreateDigester

protected abstract void recreateDigester()

Recreates all digesters that are used by parsing the OAI XML. This method is called initiall once and later on network errors before parsing same document again. This allows to recover from document parsing failing somewhere in the middle of a document.

doParse

protected boolean doParse(Supplier<ExtendedDigester> digSupplier,
                          String url,
                          AtomicReference<Instant> checkModifiedDate)
                   throws Exception

Harvests a URL using the suplied digester.

Parameters:

digSupplier - a Supplier that gives access to a (possibly recreated) digester instance.

url - the URL is parsed by this digester instance.

checkModifiedDate - for static repositories, it is possible to give a reference to a Instant for checking the last modification, in this case false is returned, if the URL was not modified. If it was modified, the reference contains a new Date object with the new modification date. Supply null for no checking of last modification, a last modification date is then not returned back (as there is no reference).

Returns:

true if harvested, false if not modified and no harvesting was done.

Throws:

Exception

getEntityResolver

protected EntityResolver getEntityResolver(EntityResolver parent)

Returns an EntityResolver that resolves all HTTP-URLS using getInputSource(java.net.URL, java.util.concurrent.atomic.AtomicReference<java.time.Instant>).

Parameters:

parent - an EntityResolver that receives all unprocessed requests

See Also:

getInputSource(java.net.URL, java.util.concurrent.atomic.AtomicReference<java.time.Instant>)

getInputSource

protected InputSource getInputSource(URL url,
                                     AtomicReference<Instant> checkModifiedDate)
                              throws IOException

Returns a SAX InputSource for retrieving stream data of an URL. It is optimized for compression of the HTTP(S) protocol and timeout checking.

Parameters:

url - the URL to open

checkModifiedDate - for static repositories, it is possible to give a reference to a Instant for checking the last modification, in this case null is returned, if the URL was not modified. If it was modified, the reference contains a new Date object with the new modification date. Supply null for no checking of last modification, a last modification date is then not returned back (as there is no reference).

Throws:

IOException

See Also:

getEntityResolver(org.xml.sax.EntityResolver)

reset

protected void reset()

Resets the internal variables.

enableMissingDocumentDelete

protected void enableMissingDocumentDelete()

Enable unseen document deletes. This should be enabled by harvester before calling addDocument(MetadataDocument), so tracking can be enabled.

cancelMissingDocumentDelete

protected void cancelMissingDocumentDelete()

Disable the property "deleteMissingDocuments" for this instance. This can be used, when the container (like a ZIP file was not modified), and all containing documents are not enumerated. To prevent deletion of all these documents call this.

close

public void close(boolean cleanShutdown)
           throws Exception

Description copied from class: Harvester

Closes harvester. All resources are freed and the Harvester.processor is closed.

Overrides:

close in class Harvester

Parameters:

cleanShutdown - enables writing of status information to the Elasticsearch instance for the next harvesting. If an error occurred during harvesting this should not be done.

Throws:

Exception - if an exception occurs during closing (various types of exceptions can be thrown). Exceptions can be thrown asynchronous and may not affect the correct document.

enumerateValidHarvesterPropertyNames

protected void enumerateValidHarvesterPropertyNames(Set<String> props)

Description copied from class: Harvester

This method is used by subclasses to enumerate all available harvester properties that are implemented by them. Overwrite this method in your own implementation and append all harvester names to the supplied Set. The public API for client code requesting property names is Harvester.getValidHarvesterPropertyNames().

Overrides:

enumerateValidHarvesterPropertyNames in class Harvester

See Also:

Harvester.getValidHarvesterPropertyNames()