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 */
017package org.apache.camel.spi;
018
019import org.apache.camel.CamelContext;
020import org.apache.camel.NamedNode;
021import org.apache.camel.Processor;
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.support.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 */
035public interface InterceptStrategy {
036
037    /**
038     * Give implementor an opportunity to wrap the target processor in a route.
039     * <p/>
040     * <b>Important:</b> See the class javadoc for advice on letting interceptor be compatible with the
041     * asynchronous routing engine.
042     *
043     * @param context       Camel context
044     * @param definition    the model this interceptor represents
045     * @param target        the processor to be wrapped
046     * @param nextTarget    the next processor to be routed to
047     * @return processor    wrapped with an interceptor or not wrapped.
048     * @throws Exception can be thrown
049     */
050    Processor wrapProcessorInInterceptors(CamelContext context, NamedNode definition,
051                                          Processor target, Processor nextTarget) throws Exception;
052}