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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/HttpRouteDirector.java $
      3  * $Revision: 620255 $
      4  * $Date: 2008-02-10 02:23:55 -0800 (Sun, 10 Feb 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 
     35 
     36 /**
     37  * Provides directions on establishing a route.
     38  * Implementations of this interface compare a planned route with
     39  * a tracked route and indicate the next step required.
     40  *
     41  * @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
     42  *
     43  *
     44  * <!-- empty lines to avoid svn diff problems -->
     45  * @version $Revision: 620255 $
     46  *
     47  * @since 4.0
     48  */
     49 public interface HttpRouteDirector {
     50 
     51     /** Indicates that the route can not be established at all. */
     52     public final static int UNREACHABLE = -1;
     53 
     54     /** Indicates that the route is complete. */
     55     public final static int COMPLETE = 0;
     56 
     57     /** Step: open connection to target. */
     58     public final static int CONNECT_TARGET = 1;
     59 
     60     /** Step: open connection to proxy. */
     61     public final static int CONNECT_PROXY = 2;
     62 
     63     /** Step: tunnel through proxy to target. */
     64     public final static int TUNNEL_TARGET = 3;
     65 
     66     /** Step: tunnel through proxy to other proxy. */
     67     public final static int TUNNEL_PROXY = 4;
     68 
     69     /** Step: layer protocol (over tunnel). */
     70     public final static int LAYER_PROTOCOL = 5;
     71 
     72 
     73     /**
     74      * Provides the next step.
     75      *
     76      * @param plan      the planned route
     77      * @param fact      the currently established route, or
     78      *                  <code>null</code> if nothing is established
     79      *
     80      * @return  one of the constants defined in this interface, indicating
     81      *          either the next step to perform, or success, or failure.
     82      *          0 is for success, a negative value for failure.
     83      */
     84     public int nextStep(RouteInfo plan, RouteInfo fact)
     85         ;
     86 
     87 
     88 } // interface HttpRouteDirector
     89