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.Processor;
020    import org.apache.camel.model.ProcessorDefinition;
021    
022    /**
023     * A strategy capable of applying interceptors to a processor
024     * <p/>
025     * Its <b>strongly</b> adviced to use an {@link org.apache.camel.AsyncProcessor} as the returned wrapped
026     * {@link Processor} which ensures the policy works well with the asynchronous routing engine.
027     * You can use the {@link org.apache.camel.processor.DelegateAsyncProcessor} to easily return an
028     * {@link org.apache.camel.AsyncProcessor} and override the
029     * {@link org.apache.camel.AsyncProcessor#process(org.apache.camel.Exchange, org.apache.camel.AsyncCallback)} to
030     * implement your interceptor logic. And just invoke the super method to <b>continue</b> routing.
031     * <p/>
032     * Mind that not all frameworks supports asynchronous routing, for example some transaction managers, such as
033     * Spring Transaction uses the current thread to store state of the transaction, and thus can't transfer this
034     * state to other threads when routing continues asynchronously.
035     *
036     * @version 
037     */
038    public interface Policy {
039    
040        /**
041         * Hook invoked before the wrap.
042         * <p/>
043         * This allows you to do any custom logic before the processor is wrapped. For example to
044         * manipulate the {@link org.apache.camel.model.ProcessorDefinition definiton}
045         *
046         * @param routeContext   the route context
047         * @param definition     the processor definition
048         */
049        void beforeWrap(RouteContext routeContext, ProcessorDefinition<?> definition);
050    
051        /**
052         * Wraps any applicable interceptors around the given processor.
053         *
054         * @param routeContext the route context
055         * @param processor the processor to be intercepted
056         * @return either the original processor or a processor wrapped in one or more processors
057         */
058        Processor wrap(RouteContext routeContext, Processor processor);
059    }