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.NamedNode;
020import org.apache.camel.Processor;
021
022/**
023 * A strategy capable of applying interceptors to a processor.
024 * <p/>
025 * Its <b>strongly</b> advised 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 */
036public interface Policy {
037
038    /**
039     * Hook invoked before the wrap.
040     * <p/>
041     * This allows you to do any custom logic before the processor is wrapped. For example to
042     * manipulate the {@link org.apache.camel.model.ProcessorDefinition definiton}.
043     *
044     * @param routeContext   the route context
045     * @param definition     the processor definition
046     */
047    void beforeWrap(RouteContext routeContext, NamedNode definition);
048
049    /**
050     * Wraps any applicable interceptors around the given processor.
051     *
052     * @param routeContext the route context
053     * @param processor the processor to be intercepted
054     * @return either the original processor or a processor wrapped in one or more processors
055     */
056    Processor wrap(RouteContext routeContext, Processor processor);
057}