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The Open Source version of the IBM Toolbox for Java

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///////////////////////////////////////////////////////////////////////////////
//
// JTOpenLite
//
// Filename:  DDMWriteCallback.java
//
// The source code contained herein is licensed under the IBM Public License
// Version 1.0, which has been approved by the Open Source Initiative.
// Copyright (C) 2011-2012 International Business Machines Corporation and
// others.  All rights reserved.
//
///////////////////////////////////////////////////////////////////////////////

package com.ibm.jtopenlite.ddm;

/**
 * Used by DDMConnection to obtain the input for a write operation from the user in a memory-conscious fashion.
 * Order of operations:
 * 

 * DDMConnection.write(file, callback)
 * --> callback.getNumberOfRecords()
 * --> begin loop
 * ------> callback.getRecordData()
 * ------> callback.getRecordDataOffset()
 * ------> callback.getNullFieldValues()
 * ------> Record is written
 * --> end loop
 * 
**/
public interface DDMWriteCallback
{
  /**
   * Returns the number of records to write, which is how many times the DDMConnection will call getRecordData() for a given write operation.
  **/
  public int getNumberOfRecords(DDMCallbackEvent event);

  /**
   * Returns the record data to write.
  **/
  public byte[] getRecordData(DDMCallbackEvent event, int recordIndex);

  /**
   * Returns the offset into the byte array returned by the prior call to getRecordData() so that a single buffer can be used to write multiple records.
  **/
  public int getRecordDataOffset(DDMCallbackEvent event, int recordIndex);

  /**
   * Returns the array of null field values, one for each field in the record to be written.
   * Returning null indicates no fields should be written with a value of null.
  **/
  public boolean[] getNullFieldValues(DDMCallbackEvent event, int recordIndex);

}