/*
 * BitStore.java
 *
 * Version: $Revision: 1759 $
 *
 * Date: $Date: 2007-04-05 15:26:37 +0000 (Thu, 05 Apr 2007) $
 *
 * Copyright (c) 2002-2007, Hewlett-Packard Company and Massachusetts
 * Institute of Technology.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Hewlett-Packard Company nor the name of the
 * Massachusetts Institute of Technology nor the names of their
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */
package org.dspace.storage.bitstore;

import java.io.InputStream;
import java.io.IOException;
import java.util.Map;

/**
 * A low-level asset store interface
 * 
 * @author Richard Rodgers
 */

public interface BitStore
{
	/**
     * Initialize the asset store
     * 
     * @param config
     *        String used to characterize configuration - may be a configuration
     *        value, or the name of a config file containing such values
     */
	public void init(String config) throws IOException;
	
	/**
     * Return an identifier unique to this asset store instance
     * 
     * @return a unique ID
     */
	public String generateId();
	
	/**
     * Retrieve the bits for the asset with ID.
     * 
     * @param id
     *         The ID of the asset to retrieve
     * @exception IOException
     *         If a problem occurs while retrieving the bits, or if no
     *         asset with ID exists in the store
     * 
     * @return The stream of bits
     */
	public InputStream get(String id) throws IOException;
	
    /**
     * Store a stream of bits.
     * 
     * <p>
     * If this method returns successfully, the bits have been stored.
     * If an exception is thrown, the bits have not been stored.
     * </p>
     * 
     * @param context
     *            The current context
     * @param in
     *            The stream of bits to store
     * @param id
     *            The ID to assign to the asset
     * @exception IOException
     *             If a problem occurs while storing the bits
     * 
     * @return Map containing technical metadata (size, checksum, etc)
     */
	public Map put(InputStream in, String id) throws IOException;
	
    /**
     * Obtain technical metadata about an asset in the asset store.
     * 
     * @param context
     *            The current context
     * @param id
     *            The ID of the asset to describe
     * @param attrs
     *            A Map whose keys consist of desired metadata fields
     * 
     * @exception IOException
     *            If a problem occurs while obtaining metadata
     * @return attrs
     *            A Map with key/value pairs of desired metadata
     */
	public Map about(String id, Map attrs) throws IOException;
	
    /**
     * Remove an asset from the asset store.
     * 
     * @param context
     *            The current context
     * @param id
     *            The ID of the asset to delete
     * @exception IOException
     *            If a problem occurs while removing the asset
     */
	public void remove(String id) throws IOException;
}