/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions are met:
 *  
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  
 *  2. 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.
 *  
 *  3. The end-user documentation included with the redistribution, if any, must 
 *     include the following acknowledgment: "This product includes software 
 *     developed by Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     Alternately, this acknowledgment may appear in the software itself, if 
 *     and wherever such third-party acknowledgments normally appear.
 *  
 *  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must 
 *     not be used to endorse or promote products derived from this software 
 *     without prior written permission. For written permission, please contact 
 *     Project JXTA at http://www.jxta.org.
 *  
 *  5. Products derived from this software may not be called "JXTA", nor may 
 *     "JXTA" appear in their name, without prior written permission of Sun.
 *  
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 SUN 
 *  MICROSYSTEMS OR ITS 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.
 *  
 *  JXTA is a registered trademark of Sun Microsystems, Inc. in the United 
 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  This software consists of voluntary contributions made by many individuals 
 *  on behalf of Project JXTA. For more information on Project JXTA, please see 
 *  http://www.jxta.org.
 *  
 *  This license is based on the BSD license adopted by the Apache Foundation. 
 */

package net.jxta.document;


import java.util.Enumeration;


/**
 * Interface for name value pairs to be associated with some base object.
 *
 * @see net.jxta.document.Attribute
 * @see net.jxta.document.StructuredDocument
 * @see net.jxta.document.Element
 */
public interface Attributable {

    /**
     * Adds an attribute with the given name and value. Some implementations
     * may support only a single value for each distinct name. Others may
     * support multiple values for each name. If the value being provided
     * replaces some other value then that value is returned otherwise null
     * is returned.
     *
     * @param name  name of the attribute.
     * @param value value for the attribute.
     * @return String  containing previous value for this name if the value
     *         is being replaced otherwise null.
     */
    String addAttribute(String name, String value);

    /**
     * Adds an attribute with the given name and value. Some implementations
     * may support only a single value for each distinct name. Others may
     * support multiple values for each name. If the value being provided
     * replaces some other value then that value is returned otherwise null
     * is returned.
     *
     * @param newAttrib new attribute.
     * @return String  containing previous value for this name if the value
     *         is being replaced otherwise null.
     */
    String addAttribute(Attribute newAttrib);

    /**
     * Returns an enumerations of the attributes associated with this object.
     * Each element is of type Attribute.
     *
     * @return Enumeration the attributes associated with this object.
     */
    Enumeration<Attribute> getAttributes();

    /**
     * Returns a single attribute which matches the name provided. If no such
     * named attribute exists then null is returned. For implementations of
     * this interface which support multiple values for each name only the
     * first value will be returned. To access all values for a name you must
     * use getAttributes.
     *
     * @param name the attribute name
     * @return Attribute the attributes matching the given name.
     */
    Attribute getAttribute(String name);
}