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    
015    package org.apache.hivemind;
016    
017    import org.apache.commons.logging.Log;
018    import 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     */
026    public 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    }