001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j;
018    
019    import java.io.Serializable;
020    
021    /**
022     *  Markers are objects that are used to add easily filterable information to log messages.
023     *
024     *  Markers can be hierarchical - each Marker may have a parent. This allows for broad categories
025     *  being subdivided into more specific categories. An example might be a Marker named "Error" with
026     *  children named "SystemError" and "ApplicationError".
027     */
028    public interface Marker extends Serializable {
029    
030        /**
031         * Returns the name of this Marker.
032         * @return The name of the Marker.
033         */
034        String getName();
035    
036        /**
037         * Returns a list of parents of this Marker.
038         * @return The parent Markers or {@code null} if this Marker has no parents.
039         */
040        Marker[] getParents();
041    
042        /**
043         * Indicates whether this Marker has references to any other Markers.
044         * @return {@code true} if the Marker has parent Markers
045         */
046        boolean hasParents();
047    
048        /**
049         * Checks whether this Marker is an instance of the specified Marker.
050         * @param m The Marker to check.
051         * @return {@code true} if this Marker or one of its ancestors is the specified Marker, {@code false} otherwise.
052         * @throws IllegalArgumentException if the argument is {@code null}
053         */
054        boolean isInstanceOf(Marker m);
055    
056        /**
057         * Checks whether this Marker is an instance of the specified Marker.
058         * @param name The name of the Marker.
059         * @return {@code true} if this Marker or one of its ancestors matches the specified name, {@code false} otherwise.
060         * @throws IllegalArgumentException if the argument is {@code null}
061         */
062        boolean isInstanceOf(String name);
063    
064        /**
065         * Adds a Marker as a parent to this Marker.
066         * @param markers The parent markers to add.
067         * @return The current Marker object, thus allowing multiple adds to be concatenated.
068         * @throws IllegalArgumentException if the argument is {@code null}
069         */
070        Marker addParents(Marker... markers);
071    
072        /**
073         * Replaces the set of parent Markers with the provided Markers.
074         * @param markers The new set of parent Markers or {@code null} to clear the parents.
075         * @return The current Marker object.
076         */
077        Marker setParents(Marker... markers);
078    
079        /**
080         * Removes the specified Marker as a parent of this Marker.
081         * @param marker The marker to remove.
082         * @return {@code true} if the marker was removed.
083         * @throws IllegalArgumentException if the argument is {@code null}
084         */
085        boolean remove(Marker marker);
086    }