
/*
 * @(#)ResourceFinderModule.java
 *
 * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution 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 Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed or intended for use in
 * the design, construction, operation or maintenance of any nuclear facility.
 */

package com.sun.xacml.finder;

import com.sun.xacml.EvaluationCtx;

import com.sun.xacml.attr.AttributeValue;


/**
 * This is the abstract class that all <code>ResourceFinder</code> modules
 * extend. All methods have default values to represent that the given
 * feature isn't supported by this module, so module writers needs only
 * implement the methods for the features they're supporting.
 *
 * @since 1.0
 * @author Seth Proctor
 */
public abstract class ResourceFinderModule
{

    /**
     * Returns this module's identifier. A module does not need to provide
     * a unique identifier, but it is a good idea, especially in support of
     * management software. Common identifiers would be the full package
     * and class name (the default if this method isn't overridden), just the
     * class name, or some other well-known string that identifies this class.
     *
     * @return this module's identifier
     */
    public String getIdentifier() {
        return getClass().getName();
    }

    /**
     * Returns true if this module supports finding resources with the
     * "Children" scope. By default this method returns false.
     *
     * @return true if the module supports the Children scope
     */
    public boolean isChildSupported() {
        return false;
    }

    /**
     * Returns true if this module supports finding resources with the
     * "Descendants" scope. By default this method returns false.
     *
     * @return true if the module supports the Descendants scope
     */
    public boolean isDescendantSupported() {
        return false;
    }

    /**
     * This is an experimental method that asks the module to invalidate any
     * cache values it may contain. This is not used by any of the core
     * processing code, but it may be used by management software that wants
     * to have some control over these modules. Since a module is free to
     * decide how or if it caches values, and whether it is capable of
     * updating values once in a cache, a module is free to intrepret this
     * message in any way it sees fit (including igoring the message). It
     * is preferable, however, for a module to make every effort to clear
     * any dynamically cached values it contains.
     * <p>
     * This method has been introduced to see what people think of this
     * functionality, and how they would like to use it. It may be removed
     * in future versions, or it may be changed to a more general
     * message-passing system (if other useful messages are identified).
     * 
     * @since 1.2
     */
    public void invalidateCache() {

    }

    /**
     * Tries to find the child Resource Ids associated with the parent. If
     * this module cannot handle the given identifier, then an empty result is
     * returned, otherwise the result will always contain at least the
     * parent Resource Id, either as a successfully resolved Resource Id or an
     * error case, but never both.
     *
     * @param parentResourceId the parent resource identifier
     * @param context the representation of the request data
     *
     * @return the result of finding child resources
     */
    public ResourceFinderResult findChildResources(AttributeValue
                                                   parentResourceId,
                                                   EvaluationCtx context) {
        return new ResourceFinderResult();
    }

    /**
     * Tries to find the child Resource Ids associated with the parent. If
     * this module cannot handle the given identifier, then an empty result is
     * returned, otherwise the result will always contain at least the
     * parent Resource Id, either as a successfully resolved Resource Id or an
     * error case, but never both.
     *
     * @deprecated As of version 1.2, replaced by
     *             {@link #findChildResources(AttributeValue,EvaluationCtx)}.
     *             This version does not provide the evaluation context,
     *             and will be removed in a future release. Also, not that
     *             this will never get called when using the default PDP.
     *
     * @param parentResourceId the parent resource identifier
     *
     * @return the result of finding child resources
     */
    public ResourceFinderResult findChildResources(AttributeValue
                                                   parentResourceId) {
        return new ResourceFinderResult();
    }

    /**
     * Tries to find the descendant Resource Ids associated with the parent. If
     * this module cannot handle the given identifier, then an empty result is
     * returned, otherwise the result will always contain at least the
     * parent Resource Id, either as a successfuly resolved Resource Id or an
     * error case, but never both.
     *
     * @param parentResourceId the parent resource identifier
     * @param context the representation of the request data
     *
     * @return the result of finding descendant resources
     */
    public ResourceFinderResult findDescendantResources(AttributeValue
                                                        parentResourceId,
                                                        EvaluationCtx
                                                        context) {
        return new ResourceFinderResult();
    }

    /**
     * Tries to find the descendant Resource Ids associated with the parent. If
     * this module cannot handle the given identifier, then an empty result is
     * returned, otherwise the result will always contain at least the
     * parent Resource Id, either as a successfuly resolved Resource Id or an
     * error case, but never both.
     *
     * @deprecated As of version 1.2, replaced by
     *          {@link #findDescendantResources(AttributeValue,EvaluationCtx)}.
     *             This version does not provide the evaluation context,
     *             and will be removed in a future release. Also, not that
     *             this will never get called when using the default PDP.
     *
     * @param parentResourceId the parent resource identifier
     *
     * @return the result of finding descendant resources
     */
    public ResourceFinderResult findDescendantResources(AttributeValue
                                                        parentResourceId) {
        return new ResourceFinderResult();
    }

}
