001    /*
002     * JBoss DNA (http://www.jboss.org/dna)
003     * See the COPYRIGHT.txt file distributed with this work for information
004     * regarding copyright ownership.  Some portions may be licensed
005     * to Red Hat, Inc. under one or more contributor license agreements.
006     * See the AUTHORS.txt file in the distribution for a full listing of 
007     * individual contributors. 
008     *
009     * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
010     * is licensed to you under the terms of the GNU Lesser General Public License as
011     * published by the Free Software Foundation; either version 2.1 of
012     * the License, or (at your option) any later version.
013     *
014     * JBoss DNA is distributed in the hope that it will be useful,
015     * but WITHOUT ANY WARRANTY; without even the implied warranty of
016     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
017     * Lesser General Public License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this software; if not, write to the Free
021     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
022     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
023     */
024    package org.jboss.dna.graph.property;
025    
026    import java.io.InputStream;
027    import java.io.Serializable;
028    import java.security.MessageDigest;
029    import net.jcip.annotations.Immutable;
030    
031    /**
032     * Value holder for binary data. Binary instances are not mutable.
033     * 
034     * @author Randall Hauch
035     */
036    @Immutable
037    public interface Binary extends Comparable<Binary>, Serializable {
038    
039        /**
040         * Get the length of this binary data.
041         * 
042         * @return the number of bytes in this binary data
043         * @see #acquire()
044         */
045        public long getSize();
046    
047        /**
048         * Get the SHA-1 hash of the contents. This hash can be used to determine whether two Binary instances contain the same
049         * content.
050         * <p>
051         * Repeatedly calling this method should generally be efficient, as it most implementations will compute the hash only once.
052         * </p>
053         * 
054         * @return the hash of the contents as a byte array, or an empty array if the hash could not be computed.
055         * @see #acquire()
056         * @see MessageDigest#digest(byte[])
057         * @see MessageDigest#getInstance(String)
058         */
059        public byte[] getHash();
060    
061        /**
062         * Get the contents of this data as a stream.
063         * 
064         * @return the stream to this data's contents
065         * @see #acquire()
066         * @throws IoException if there is a problem returning the stream
067         */
068        public InputStream getStream();
069    
070        /**
071         * Get the contents of this data as a byte array.
072         * 
073         * @return the data as an array
074         * @see #acquire()
075         * @throws IoException if there is a problem returning the bytes
076         */
077        public byte[] getBytes();
078    
079        /**
080         * Acquire any resources for this data. This method must be called before any other method on this object.
081         * 
082         * @see #release()
083         */
084        public void acquire();
085    
086        /**
087         * Release any acquired resources. This method must be called after a client is finished with this value.
088         * 
089         * @see #acquire()
090         */
091        public void release();
092    
093    }