001// Copyright 2004, 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
015package org.apache.hivemind;
016
017import org.apache.commons.logging.Log;
018import org.apache.hivemind.internal.Module;
019
020/**
021 * Used when constructing an interceptor stack around
022 * a service implementation instance.
023 *
024 * @author Howard Lewis Ship
025 */
026public interface InterceptorStack
027{       
028        /**
029         * Return the full id of the service extension point for which
030         * interceptors are being fabricated.
031         */
032        
033        public String getServiceExtensionPointId();
034        
035        /**
036         * Returns the module which contains the service extension point.
037         */
038        
039        public Module getServiceModule();
040        
041        /**
042         * Returns the interface for the service; the same
043         * as {@link org.apache.hivemind.internal.ServicePoint#getServiceInterface()}.
044         */
045        public Class getServiceInterface();
046        
047        /**
048         * Returns the current top object on the stack.
049         */
050        public Object peek();
051        
052        /**
053         * Pushes a new instance onto the stack.  The new instance
054         * should be a wrapper around {@link #peek()}, and should
055         * implement the service extension point's interface.
056         * 
057         * <p>The stack checks that the interceptor is not null,
058         * and that the interceptor implements the service interface.
059         */
060        
061        public void push(Object interceptor);
062        
063        /**
064         * Returns the Log instance that should be used to log any information
065         * about the service, or the construction of the service.
066         */
067        
068        public Log getServiceLog();
069}