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The Spring Batch Infrastructure is a set of low-level components, interfaces and tools for batch processing applications and optimisations.

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/*
 * Copyright 2006-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.batch.item;

/**
 * 
 * Basic interface for generic output operations. Class implementing this
 * interface will be responsible for serializing objects as necessary.
 * Generally, it is responsibility of implementing class to decide which
 * technology to use for mapping and how it should be configured.
 * 
 * 
 * 
 * Due to the nature of batch processing, it is expected that most writers will
 * buffer output. A flush method is provided to the interface in order to ensure
 * that any buffers can be flushed before a transaction is committed. Along the
 * same lines, if a transaction has been rolled back, then the contents of any
 * buffers should be thrown away.
 * 
 * 
 * @author Dave Syer
 * @author Lucas Ward
 */
public interface ItemWriter {

	/**
	 * Process the supplied data element. Will be called multiple times during a
	 * larger batch operation. Will not be called with null data in normal
	 * operation.
	 * 
	 * @throws Exception if there are errors. If the writer is used inside a
	 * retry or a batch the framework will catch the exception and convert or
	 * rethrow it as appropriate.
	 */
	void write(Object item) throws Exception;

	/**
	 * Flush any buffers that are being held. This will usually be performed
	 * prior to committing any transactions.
	 * @throws FlushFailedException in case of an error.  If this exception is
	 * thrown the writer may be in an inconsistent state and manual intervention
	 * might be required to reconcile the data with persistent output.
	 */
	void flush() throws FlushFailedException;

	/**
	 * Clear any buffers that are being held. This will usually be performed
	 * prior to rolling back any transactions.
	 * @throws ClearFailedException in case of an error. If this exception is
	 * thrown the writer may be in an inconsistent state and manual intervention
	 * might be required to reconcile the data with persistent output.
	 */
	void clear() throws ClearFailedException;
}