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.conn.routing; 029 030import org.apache.http.HttpException; 031import org.apache.http.HttpHost; 032import org.apache.http.HttpRequest; 033import org.apache.http.protocol.HttpContext; 034 035/** 036 * Encapsulates logic to compute a {@link HttpRoute} to a target host. 037 * Implementations may for example be based on parameters, or on the 038 * standard Java system properties. 039 * <p> 040 * Implementations of this interface must be thread-safe. Access to shared 041 * data must be synchronized as methods of this interface may be executed 042 * from multiple threads. 043 * </p> 044 * 045 * @since 4.0 046 */ 047public interface HttpRoutePlanner { 048 049 /** 050 * Determines the route for a request. 051 * 052 * @param target the target host for the request. 053 * Implementations may accept {@code null} 054 * if they can still determine a route, for example 055 * to a default target or by inspecting the request. 056 * @param request the request to execute 057 * @param context the context to use for the subsequent execution. 058 * Implementations may accept {@code null}. 059 * 060 * @return the route that the request should take 061 * 062 * @throws HttpException in case of a problem 063 */ 064 public HttpRoute determineRoute(HttpHost target, 065 HttpRequest request, 066 HttpContext context) throws HttpException; 067 068}