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      1 /*
      2  * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/conn/routing/HttpRoutePlanner.java $
      3  * $Revision: 613654 $
      4  * $Date: 2008-01-20 11:00:19 -0800 (Sun, 20 Jan 2008) $
      5  *
      6  * ====================================================================
      7  * Licensed to the Apache Software Foundation (ASF) under one
      8  * or more contributor license agreements.  See the NOTICE file
      9  * distributed with this work for additional information
     10  * regarding copyright ownership.  The ASF licenses this file
     11  * to you under the Apache License, Version 2.0 (the
     12  * "License"); you may not use this file except in compliance
     13  * with the License.  You may obtain a copy of the License at
     14  *
     15  *   http://www.apache.org/licenses/LICENSE-2.0
     16  *
     17  * Unless required by applicable law or agreed to in writing,
     18  * software distributed under the License is distributed on an
     19  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     20  * KIND, either express or implied.  See the License for the
     21  * specific language governing permissions and limitations
     22  * under the License.
     23  * ====================================================================
     24  *
     25  * This software consists of voluntary contributions made by many
     26  * individuals on behalf of the Apache Software Foundation.  For more
     27  * information on the Apache Software Foundation, please see
     28  * <http://www.apache.org/>.
     29  *
     30  */
     31 
     32 package org.apache.http.conn.routing;
     33 
     34 import org.apache.http.HttpException;
     35 import org.apache.http.HttpHost;
     36 import org.apache.http.HttpRequest;
     37 import org.apache.http.protocol.HttpContext;
     38 
     39 
     40 
     41 /**
     42  * Encapsulates logic to compute a {@link HttpRoute} to a target host.
     43  * Implementations may for example be based on parameters, or on the
     44  * standard Java system properties.
     45  */
     46 public interface HttpRoutePlanner {
     47 
     48     /**
     49      * Determines the route for a request.
     50      *
     51      * @param target    the target host for the request.
     52      *                  Implementations may accept <code>null</code>
     53      *                  if they can still determine a route, for example
     54      *                  to a default target or by inspecting the request.
     55      * @param request   the request to execute
     56      * @param context   the context to use for the subsequent execution.
     57      *                  Implementations may accept <code>null</code>.
     58      *
     59      * @return  the route that the request should take
     60      *
     61      * @throws HttpException    in case of a problem
     62      */
     63     public HttpRoute determineRoute(HttpHost target,
     64                                     HttpRequest request,
     65                                     HttpContext context)
     66         throws HttpException
     67         ;
     68 
     69 }
     70