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
32package 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 */
49public 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