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 import org.apache.http.HttpException;
31 import org.apache.http.HttpHost;
32 import org.apache.http.HttpRequest;
33 import org.apache.http.protocol.HttpContext;
34
35 /**
36 * Encapsulates logic to compute a {@link HttpRoute} to a target host.
37 * Implementations may for example be based on parameters, or on the
38 * standard Java system properties.
39 * <p>
40 * Implementations of this interface must be thread-safe. Access to shared
41 * data must be synchronized as methods of this interface may be executed
42 * from multiple threads.
43 * </p>
44 *
45 * @since 4.0
46 */
47 public interface HttpRoutePlanner {
48
49 /**
50 * Determines the route for a request.
51 *
52 * @param target the target host for the request.
53 * Implementations may accept {@code null}
54 * if they can still determine a route, for example
55 * to a default target or by inspecting the request.
56 * @param request the request to execute
57 * @param context the context to use for the subsequent execution.
58 * Implementations may accept {@code null}.
59 *
60 * @return the route that the request should take
61 *
62 * @throws HttpException in case of a problem
63 */
64 HttpRoute determineRoute(HttpHost target,
65 HttpRequest request,
66 HttpContext context) throws HttpException;
67
68 }