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.hc.client5.http.routing;
29
30 import org.apache.hc.client5.http.RouteInfo;
31 import org.apache.hc.core5.annotation.Contract;
32 import org.apache.hc.core5.annotation.ThreadingBehavior;
33
34 /**
35 * Provides directions on establishing a route.
36 * Implementations of this interface compare a planned route with
37 * a tracked route and indicate the next step required.
38 *
39 * @since 4.0
40 */
41 @Contract(threading = ThreadingBehavior.STATELESS)
42 public interface HttpRouteDirector {
43
44 /** Indicates that the route can not be established at all. */
45 int UNREACHABLE = -1;
46
47 /** Indicates that the route is complete. */
48 int COMPLETE = 0;
49
50 /** Step: open connection to target. */
51 int CONNECT_TARGET = 1;
52
53 /** Step: open connection to proxy. */
54 int CONNECT_PROXY = 2;
55
56 /** Step: tunnel through proxy to target. */
57 int TUNNEL_TARGET = 3;
58
59 /** Step: tunnel through proxy to other proxy. */
60 int TUNNEL_PROXY = 4;
61
62 /** Step: layer protocol (over tunnel). */
63 int LAYER_PROTOCOL = 5;
64
65
66 /**
67 * Provides the next step.
68 *
69 * @param plan the planned route
70 * @param fact the currently established route, or
71 * {@code null} if nothing is established
72 *
73 * @return one of the constants defined in this interface, indicating
74 * either the next step to perform, or success, or failure.
75 * 0 is for success, a negative value for failure.
76 */
77 int nextStep(RouteInfo plan, RouteInfo fact);
78
79 }