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.camel.spi;
018    
019    import org.apache.camel.CamelContext;
020    import org.apache.camel.Processor;
021    import org.apache.camel.model.ProcessorDefinition;
022    
023    /**
024     * The purpose of this interface is to allow an implementation to wrap
025     * processors in a route with interceptors.  For example, a possible
026     * usecase is to gather performance statistics at the processor's level.
027     * <p/>
028     * Its <b>strongly</b> adviced to use an {@link org.apache.camel.AsyncProcessor} as the returned wrapped
029     * {@link Processor} which ensures the interceptor works well with the asynchronous routing engine.
030     * You can use the {@link org.apache.camel.processor.DelegateAsyncProcessor} to easily return an
031     * {@link org.apache.camel.AsyncProcessor} and override the
032     * {@link org.apache.camel.AsyncProcessor#process(org.apache.camel.Exchange, org.apache.camel.AsyncCallback)} to
033     * implement your interceptor logic. And just invoke the super method to <b>continue</b> routing.
034     *
035     * @version 
036     */
037    public interface InterceptStrategy {
038    
039        /**
040         * This method is invoked by
041         * {@link ProcessorDefinition#wrapProcessor(RouteContext, Processor)}
042         * to give the implementor an opportunity to wrap the target processor
043         * in a route.
044         * <p/>
045         * <b>Important:</b> See the class javadoc for advice on letting interceptor be compatible with the
046         * asynchronous routing engine.
047         *
048         * @param context       Camel context
049         * @param definition    the model this interceptor represents
050         * @param target        the processor to be wrapped
051         * @param nextTarget    the next processor to be routed to
052         * @return processor    wrapped with an interceptor or not wrapped.
053         * @throws Exception can be thrown
054         */
055        Processor wrapProcessorInInterceptors(CamelContext context, ProcessorDefinition<?> definition, 
056                                              Processor target, Processor nextTarget) throws Exception;
057    }