camel-2.8.x/camel-core/src/main/java/org/apache/camel/spi/Policy.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.camel.spi;

import org.apache.camel.Processor;
import org.apache.camel.model.ProcessorDefinition;

/**
 * A strategy capable of applying interceptors to a processor
 * <p/>
 * Its <b>strongly</b> adviced to use an {@link org.apache.camel.AsyncProcessor} as the returned wrapped
 * {@link Processor} which ensures the policy works well with the asynchronous routing engine.
 * You can use the {@link org.apache.camel.processor.DelegateAsyncProcessor} to easily return an
 * {@link org.apache.camel.AsyncProcessor} and override the
 * {@link org.apache.camel.AsyncProcessor#process(org.apache.camel.Exchange, org.apache.camel.AsyncCallback)} to
 * implement your interceptor logic. And just invoke the super method to <b>continue</b> routing.
 * <p/>
 * Mind that not all frameworks supports asynchronous routing, for example some transaction managers, such as
 * Spring Transaction uses the current thread to store state of the transaction, and thus can't transfer this
 * state to other threads when routing continues asynchronously.
 *
 * @version 
 */
public interface Policy {

    /**
     * Hook invoked before the wrap.
     * <p/>
     * This allows you to do any custom logic before the processor is wrapped. For example to
     * manipulate the {@link org.apache.camel.model.ProcessorDefinition definiton}
     *
     * @param routeContext   the route context
     * @param definition     the processor definition
     */
    void beforeWrap(RouteContext routeContext, ProcessorDefinition<?> definition);

    /**
     * Wraps any applicable interceptors around the given processor.
     *
     * @param routeContext the route context
     * @param processor the processor to be intercepted
     * @return either the original processor or a processor wrapped in one or more processors
     */
    Processor wrap(RouteContext routeContext, Processor processor);
}