001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.impl.execchain;
029
030import java.io.IOException;
031
032import org.apache.http.HttpException;
033import org.apache.http.client.methods.CloseableHttpResponse;
034import org.apache.http.client.methods.HttpExecutionAware;
035import org.apache.http.client.methods.HttpRequestWrapper;
036import org.apache.http.client.protocol.HttpClientContext;
037import org.apache.http.conn.routing.HttpRoute;
038
039/**
040 * This interface represents an element in the HTTP request execution chain. Each element can
041 * either be a decorator around another element that implements a cross cutting aspect or
042 * a self-contained executor capable of producing a response for the given request.
043 * <p>
044 * Important: please note it is required for decorators that implement post execution aspects
045 * or response post-processing of any sort to release resources associated with the response
046 * by calling {@link CloseableHttpResponse#close()} methods in case of an I/O, protocol or
047 * runtime exception, or in case the response is not propagated to the caller.
048 * </p>
049 *
050 * @since 4.3
051 */
052public interface ClientExecChain {
053
054    /**
055     * Executes th request either by transmitting it to the target server or
056     * by passing it onto the next executor in the request execution chain.
057     *
058     * @param route connection route.
059     * @param request current request.
060     * @param clientContext current HTTP context.
061     * @param execAware receiver of notifications of blocking I/O operations.
062     * @return HTTP response either received from the opposite endpoint
063     *   or generated locally.
064     * @throws IOException in case of a I/O error.
065     *   (this type of exceptions are potentially recoverable).
066     * @throws HttpException in case of an HTTP protocol error
067     *   (usually this type of exceptions are non-recoverable).
068     */
069    CloseableHttpResponse execute(
070            HttpRoute route,
071            HttpRequestWrapper request,
072            HttpClientContext clientContext,
073            HttpExecutionAware execAware) throws IOException, HttpException;
074
075}