001/* Group.java -- Represents a group of Principals
002   Copyright (C) 1998, 2001 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.security.acl;
039
040import java.security.Principal;
041import java.util.Enumeration;
042
043/**
044 * This interface represents a group of <code>Principals</code>.  Note that
045 * since this interface extends <code>Principal</code>, a <code>Group</code>
046 * can be used where ever a <code>Principal</code> is requested.  This
047 * includes arguments to the methods in this interface.
048 *
049 * @version 0.0
050 *
051 * @author Aaron M. Renn (arenn@urbanophile.com)
052 */
053public interface Group extends Principal
054{
055  /**
056   * This method adds a new <code>Principal</code> to this group.
057   *
058   * @param user The new <code>Principal</code> to add
059   *
060   * @return <code>true</code> if the user was successfully added or <code>false</code> if the user is already a member
061   */
062  boolean addMember(Principal user);
063
064  /**
065   * This method deletes a member from the group.
066   *
067   * @param user The <code>Principal</code> to delete
068   *
069   * @return <code>true</code> if the user was successfully deleted or <code>false</code> if the user is not a member of the group
070   */
071  boolean removeMember(Principal user);
072
073  /**
074   * This method tests whether or not a given <code>Principal</code> is a
075   * member of this group.
076   *
077   * @param member The <code>Principal</code> to test for membership
078   *
079   * @return <code>true</code> if the user is member, <code>false</code> otherwise
080   */
081  boolean isMember(Principal member);
082
083  /**
084   * This method returns a list of all members of the group as an
085   * <code>Enumeration</code>.
086   *
087   * @return The list of all members of the group
088   */
089  Enumeration<? extends Principal> members();
090}