FormatFilter.java

/*
 * FormatFilter.java
 *
 * Version: $Revision: 3733 $
 *
 * Date: $Date: 2009-04-24 03:52:11 +0000 (Fri, 24 Apr 2009) $
 *
 * Copyright (c) 2002-2009, The DSpace Foundation.  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 DSpace Foundation nor the names of its
 * 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.app.mediafilter;

import java.io.InputStream;

import org.dspace.content.Bitstream;
import org.dspace.content.Item;
import org.dspace.core.Context;

/**
 * Public interface for any class which transforms or converts content/bitstreams 
 * from one format to another.  This interface should be implemented by any class
 * which defines a "filter" to be run by the MediaFilterManager.
 */
public interface FormatFilter
{
    /**
     * Get a filename for a newly created filtered bitstream
     * 
     * @param sourceName
     *            name of source bitstream
     * @return filename generated by the filter - for example, document.pdf
     *         becomes document.pdf.txt
     */
    public String getFilteredName(String sourceName);

    /**
     * @return name of the bundle this filter will stick its generated
     *         Bitstreams
     */
    public String getBundleName();

    /**
     * @return name of the bitstream format (say "HTML" or "Microsoft Word")
     *         returned by this filter look in the bitstream format registry or
     *         mediafilter.cfg for valid format strings.
     */
    public String getFormatString();

    /**
     * @return string to describe the newly-generated Bitstream's - how it was
     *         produced is a good idea
     */
    public String getDescription();

    /**
     * @param source
     *            input stream
     * 
     * @return result of filter's transformation, written out to a bitstream
     */
    public InputStream getDestinationStream(InputStream source)
            throws Exception;

    /**
     * Perform any pre-processing of the source bitstream *before* the actual 
     * filtering takes place in MediaFilterManager.processBitstream().
     * <p>
     * Return true if pre-processing is successful (or no pre-processing
     * is necessary).  Return false if bitstream should be skipped
     * for any reason.
     * 
     * 
     * @param c
     *            context
     * @param item
     *            item containing bitstream to process
     * @param source
     *            source bitstream to be processed
     * 
     * @return true if bitstream processing should continue, 
     * 			false if this bitstream should be skipped
     */
    public boolean preProcessBitstream(Context c, Item item, Bitstream source)
            throws Exception;
        
    /**
     * Perform any post-processing of the generated bitstream *after* this
     * filter has already been run.
     * <p>
     * Return true if pre-processing is successful (or no pre-processing
     * is necessary).  Return false if bitstream should be skipped
     * for some reason.
     * 
     * 
     * @param c
     *            context
     * @param item
     *            item containing bitstream to process
     * @param generatedBitstream
     *            the bitstream which was generated by
     *            this filter.
     */
    public void postProcessBitstream(Context c, Item item, Bitstream generatedBitstream)
            throws Exception;
}