001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one
003     *  or more contributor license agreements.  See the NOTICE file
004     *  distributed with this work for additional information
005     *  regarding copyright ownership.  The ASF licenses this file
006     *  to you under the Apache License, Version 2.0 (the
007     *  "License"); you may not use this file except in compliance
008     *  with the License.  You may obtain a copy of the License at
009     *  
010     *    http://www.apache.org/licenses/LICENSE-2.0
011     *  
012     *  Unless required by applicable law or agreed to in writing,
013     *  software distributed under the License is distributed on an
014     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     *  KIND, either express or implied.  See the License for the
016     *  specific language governing permissions and limitations
017     *  under the License. 
018     *  
019     */
020    package org.apache.directory.shared.asn1.codec.stateful;
021    
022    
023    /**
024     * Monitors decoder activity. This class borrowed some from the <code>
025     * org.xml.sax.ErrorHandler</code>
026     * interface and its documentation. A monitor is a generalized callback for any
027     * sort of activity used for tracking both successes and failures. So you'll
028     * realize similarities between monitors and callbacks especially where the
029     * callbackOccurred() method is concerned.
030     * 
031     * @author <a href="mailto:dev@directory.apache.org"> Apache Directory Project</a>
032     * @version $Rev: 664290 $
033     */
034    public interface DecoderMonitor
035    {
036        /**
037         * Receive notification of a recoverable error. This callback is used to
038         * denote a failure to handle a unit of data to be encoded or decoded. The
039         * entire [en|de]codable unit is lost but the [en|de]coding operation can
040         * still proceed.
041         * 
042         * @param decoder
043         *            the decoder that had the error
044         * @param exception
045         *            the error information encapsulated in an exception
046         */
047        void error( StatefulDecoder decoder, Exception exception );
048    
049    
050        /**
051         * Receive notification of a non-recoverable error. The application must
052         * assume that the stream data is unusable after the decoder has invoked
053         * this method, and should continue (if at all) only for the sake of
054         * collecting addition error messages: in fact, decoders are free to stop
055         * reporting any other events once this method has been invoked.
056         * 
057         * @param decoder
058         *            the decoder that had the failure
059         * @param exception
060         *            the warning information encapsulated in an exception
061         */
062        void fatalError( StatefulDecoder decoder, Exception exception );
063    
064    
065        /**
066         * Receive notification of a warning. The decoder must continue to provide
067         * normal callbacks after invoking this method: it should still be possible
068         * for the application to process the encoded data through to the end.
069         * 
070         * @param decoder
071         *            the decoder that had the error
072         * @param exception
073         *            the warning information encapsulated in an exception
074         */
075        void warning( StatefulDecoder decoder, Exception exception );
076    
077    
078        /**
079         * Monitors callbacks that deliver a fully decoded object.
080         * 
081         * @param decoder the stateful decoder driving the callback
082         * @param cb the callback to call when the decoder has done its job
083         * @param decoded the object that was decoded
084         */
085        void callbackOccured( StatefulDecoder decoder, DecoderCallback cb, Object decoded );
086    
087    
088        /**
089         * Monitors changes to the callback.
090         * 
091         * @param decoder the decoder whose callback was set
092         * @param oldcb the unset old callback, or null if none was set
093         * @param newcb the newly set callback, or null if callback is cleared
094         */
095        void callbackSet( StatefulDecoder decoder, DecoderCallback oldcb, DecoderCallback newcb );
096    }