ExportListener (MarkLogic Java Client API 8.1.0)

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

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java.lang.Object

com.marklogic.client.datamovement.ExportListener

All Implemented Interfaces:: BatchListener<QueryBatch>, QueryBatchListener

Direct Known Subclasses:: ExportToWriterListener

public class ExportListener extends Object implements QueryBatchListener

Reads document contents (and optionally metadata) for each batch, then sends each document to any listeners registered with onDocumentReady for further processing or writing to any target supported by Java. Supports reading partial documents via transforms. Supports exporting all documents at a consistent point-in-time using withConsistentSnapshot.

For example:


     QueryBatcher exportBatcher = moveMgr.newQueryBatcher(query)
         .withConsistentSnapshot()
         .onUrisReady(
           new ExportListener()
             .withConsistentSnapshot()
             .onDocumentReady(doc -> {
               logger.debug("Contents=[{}]", doc.getContentAs(String.class));
             })
         )
         .onQueryFailure(exception -> exception.printStackTrace());

     JobTicket ticket = moveMgr.startJob(exportBatcher);
     exportBatcher.awaitCompletion();
     moveMgr.stopJob(ticket);

By default only document contents are retrieved. If you would also like metadata, make sure to call withMetadataCategory to configure which categories of metadata you desire.

As with all the provided listeners, this listener will not meet the needs of all applications but the source code for it should serve as helpful sample code so you can write your own custom listeners.

Constructor Summary

Constructors

Constructor

Description

ExportListener()
Method Summary

Modifier and Type

Method

Description

protected List<BatchFailureListener<QueryBatch>>

getBatchFailureListeners()

protected DocumentPage

getDocs(QueryBatch batch)

void

initializeListener(QueryBatcher queryBatcher)

This implementation of initializeListener adds this instance of ExportListener to the two RetryListener's in this QueryBatcher so they will retry any batches that fail during the read request.

ExportListener

onDocumentPageReady(Consumer<DocumentPage> listener)

Sets a listener to process a page of retrieved documents.

ExportListener

onDocumentReady(Consumer<DocumentRecord> listener)

Adds a listener to process each retrieved document, which is the way users of ExportListener can provide custom code to export documents.

ExportListener

onFailure(BatchFailureListener<QueryBatch> listener)

When a batch fails or a callback throws an Exception, run this listener code.

void

processEvent(QueryBatch batch)

This is the method QueryBatcher calls for ExportListener to do its thing.

ExportListener

withConsistentSnapshot()

Specifies that documents should be retrieved as they were when this QueryBatcher job started.

ExportListener

withMetadataCategory(DocumentManager.Metadata category)

Adds a metadata category to retrieve and make available from DocumentRecord.getMetadata to listeners registered with onDocumentReady.

ExportListener

withNonDocumentFormat(Format nonDocumentFormat)

Sets the format for metadata available from DocumentRecord.getMetadata to listeners registered with onDocumentReady (assuming withMetadataCategory has been called to request specific metdata).

ExportListener

withTransform(ServerTransform transform)

Sets the server tranform to modify the document contents.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details
- ExportListener
  
  public ExportListener()
Method Details
- getDocs
  
  protected DocumentPage getDocs(QueryBatch batch)
- initializeListener
  
  public void initializeListener(QueryBatcher queryBatcher)
  
  This implementation of initializeListener adds this instance of ExportListener to the two RetryListener's in this QueryBatcher so they will retry any batches that fail during the read request.
  
  Specified by:
  
  initializeListener in interface QueryBatchListener
  
  Parameters:
  
  queryBatcher - the QueryBatcher which will call this Listener
- processEvent
  
  public void processEvent(QueryBatch batch)
  
  This is the method QueryBatcher calls for ExportListener to do its thing. You should not need to call it.
  
  Specified by:
  
  processEvent in interface BatchListener<QueryBatch>
  
  Specified by:
  
  processEvent in interface QueryBatchListener
  
  Parameters:
  
  batch - the batch of uris and some metadata about the current status of the job
- withConsistentSnapshot
  
  public ExportListener withConsistentSnapshot()
  
  Specifies that documents should be retrieved as they were when this QueryBatcher job started. This enables a point-in-time export so that all documents are as they were at that point in time. This requires that the server be configured to allow such queries by setting the [merge timestamp](https://docs.marklogic.com/guide/app-dev/point_in_time#id_32468) to a timestamp before the job starts or a sufficiently large negative value. This should only be used when the QueryBatcher is constructed with a query, not with an Iterator.
  Returns:
  
  this instance for method chaining
  
  See Also:
  - QueryBatcher.withConsistentSnapshot()
- withMetadataCategory
  
  public ExportListener withMetadataCategory(DocumentManager.Metadata category)
  
  Adds a metadata category to retrieve and make available from DocumentRecord.getMetadata to listeners registered with onDocumentReady. To specify the format for the metdata, call withNonDocumentFormat.
  Parameters:
  
  category - the metadata category to retrieve
  
  Returns:
  
  this instance for method chaining
  
  See Also:
  - DocumentManager.setMetadataCategories
- withNonDocumentFormat
  
  public ExportListener withNonDocumentFormat(Format nonDocumentFormat)
  
  Sets the format for metadata available from DocumentRecord.getMetadata to listeners registered with onDocumentReady (assuming withMetadataCategory has been called to request specific metdata). If setNonDocumentFormat is not called, the server default format will be used.
  Parameters:
  
  nonDocumentFormat - the format in which retrieve the metadata
  
  Returns:
  
  this instance for method chaining
  
  See Also:
  - DocumentManager.setNonDocumentFormat
- withTransform
  
  public ExportListener withTransform(ServerTransform transform)
  
  Sets the server tranform to modify the document contents.
  
  Parameters:
  
  transform - the name of the transform already installed in the REST server
  
  Returns:
  
  this instance for method chaining
- onDocumentReady
  
  public ExportListener onDocumentReady(Consumer<DocumentRecord> listener)
  
  Adds a listener to process each retrieved document, which is the way users of ExportListener can provide custom code to export documents. This custom code could write the document or a portion of the document to the file system, a REST service, or any target supported by Java. If further information is required about the document beyond what DocumentRecord can provide, register a listener with QueryBatcher.onUrisReady instead.
  Parameters:
  
  listener - the code which will process each document
  
  Returns:
  
  this instance for method chaining
  
  See Also:
  - Consumer
  - DocumentRecord
- onDocumentPageReady
  
  public ExportListener onDocumentPageReady(Consumer<DocumentPage> listener)
  
  Sets a listener to process a page of retrieved documents. Useful for when documents should be written to an external system where it's more efficient to make batched writes to that system. Note that close() does need to be invoked on the DocumentPage; this class will handle that.
  Parameters:
  
  listener - the code which will process each page of documents
  
  Returns:
  
  this instance for method chaining
  
  Since:
  
  6.2.0
  
  See Also:
  - Consumer
  - DocumentPage
- onFailure
  
  public ExportListener onFailure(BatchFailureListener<QueryBatch> listener)
  
  When a batch fails or a callback throws an Exception, run this listener code. Multiple listeners can be registered with this method.
  
  Parameters:
  
  listener - the code to run when a failure occurs
  
  Returns:
  
  this instance for method chaining
- getBatchFailureListeners
  
  protected List<BatchFailureListener<QueryBatch>> getBatchFailureListeners()

Class ExportListener

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Details

ExportListener

Method Details

getDocs

initializeListener

processEvent

withConsistentSnapshot

withMetadataCategory

withNonDocumentFormat

withTransform

onDocumentReady

onDocumentPageReady

onFailure

getBatchFailureListeners