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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.conn.routing;
29  
30  /**
31   * Provides directions on establishing a route.
32   * Implementations of this interface compare a planned route with
33   * a tracked route and indicate the next step required.
34   *
35   * @since 4.0
36   */
37  public interface HttpRouteDirector {
38  
39      /** Indicates that the route can not be established at all. */
40      public final static int UNREACHABLE = -1;
41  
42      /** Indicates that the route is complete. */
43      public final static int COMPLETE = 0;
44  
45      /** Step: open connection to target. */
46      public final static int CONNECT_TARGET = 1;
47  
48      /** Step: open connection to proxy. */
49      public final static int CONNECT_PROXY = 2;
50  
51      /** Step: tunnel through proxy to target. */
52      public final static int TUNNEL_TARGET = 3;
53  
54      /** Step: tunnel through proxy to other proxy. */
55      public final static int TUNNEL_PROXY = 4;
56  
57      /** Step: layer protocol (over tunnel). */
58      public final static int LAYER_PROTOCOL = 5;
59  
60  
61      /**
62       * Provides the next step.
63       *
64       * @param plan      the planned route
65       * @param fact      the currently established route, or
66       *                  {@code null} if nothing is established
67       *
68       * @return  one of the constants defined in this interface, indicating
69       *          either the next step to perform, or success, or failure.
70       *          0 is for success, a negative value for failure.
71       */
72      public int nextStep(RouteInfo plan, RouteInfo fact);
73  
74  }