001    // Copyright 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.describe;
016    
017    import org.apache.tapestry.IMarkupWriter;
018    import org.apache.tapestry.event.ReportStatusListener;
019    
020    /**
021     * Service for collecting together status information across the framework; service implementations
022     * implement the {@link org.apache.tapestry.event.ReportStatusListener} interface and register
023     * themselves as listeners here. When desired, the {@link #fireReportStatus(IMarkupWriter)} event
024     * will invoke the listener method on each registered object.
025     * 
026     * @author Howard M. Lewis Ship
027     * @since 4.0
028     */
029    public interface ReportStatusHub
030    {
031        /**
032         * Adds the listener; listeners will be invoked in the order in which they are added.
033         * <strong>Note: only service implementation that are singletons should be report status
034         * listeners. Threaded or pooled implementations should not be added; or should be careful to
035         * add and remove themselves from the hub directly.</strong>
036         * 
037         * @param listener
038         */
039        public void addReportStatusListener(ReportStatusListener listener);
040    
041        public void removeReportStatusListener(ReportStatusListener listener);
042    
043        /**
044         * Generates an HTML status report by invoking
045         * {@link ReportStatusListener#reportStatus(ReportStatusEvent)} on each registered listener.
046         * 
047         * @param writer
048         *            a markup writer to send the report to.
049         */
050        public void fireReportStatus(IMarkupWriter writer);
051    }