/*
 * @(#)Owner.java	1.13 00/02/02
 *
 * Copyright 1996-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.security.acl;

import java.security.Principal;

/**
 * Interface for managing owners of Access Control Lists (ACLs) or ACL 
 * configurations. (Note that the Acl interface in the 
 * <code> java.security.acl </code> package extends this Owner
 * interface.) The initial owner Principal should be specified as an 
 * argument to the constructor of the class implementing this interface.   
 *   
 * @see java.security.acl.Acl    
 *
 */
public interface Owner {

    /**
     * Adds an owner. Only owners can modify ACL contents. The caller 
     * principal must be an owner of the ACL in order to invoke this method.
     * That is, only an owner can add another owner. The initial owner is 
     * configured at ACL construction time. 
     * 
     * @param caller the principal invoking this method. It must be an owner 
     * of the ACL.
     * 
     * @param owner the owner that should be added to the list of owners.
     * 
     * @return true if successful, false if owner is already an owner.
     * @exception NotOwnerException if the caller principal is not an owner 
     * of the ACL.
     */
    public boolean addOwner(Principal caller, Principal owner)
      throws NotOwnerException;

    /** 
     * Deletes an owner. If this is the last owner in the ACL, an exception is 
     * raised.<p>
     * 
     * The caller principal must be an owner of the ACL in order to invoke 
     * this method. 
     * 
     * @param caller the principal invoking this method. It must be an owner 
     * of the ACL.
     * 
     * @param owner the owner to be removed from the list of owners.
     * 
     * @return true if the owner is removed, false if the owner is not part 
     * of the list of owners.
     * 
     * @exception NotOwnerException if the caller principal is not an owner 
     * of the ACL.
     * 
     * @exception LastOwnerException if there is only one owner left, so that
     * deleteOwner would leave the ACL owner-less.
     */
    public boolean deleteOwner(Principal caller, Principal owner)
      throws NotOwnerException, LastOwnerException;

    /**
     * Returns true if the given principal is an owner of the ACL.
     * 
     * @param owner the principal to be checked to determine whether or not 
     * it is an owner.
     * 
     * @return true if the passed principal is in the list of owners, false 
     * if not.
     */
    public boolean isOwner(Principal owner);

}