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.protocol;
29
30 /**
31 * HttpContext represents execution state of an HTTP process. It is a structure
32 * that can be used to map an attribute name to an attribute value.
33 * <p>
34 * The primary purpose of the HTTP context is to facilitate information sharing
35 * among various logically related components. HTTP context can be used
36 * to store a processing state for one message or several consecutive messages.
37 * Multiple logically related messages can participate in a logical session
38 * if the same context is reused between consecutive messages.
39 * </p>
40 * <p>
41 * IMPORTANT: Please note HTTP context implementation, even when thread safe,
42 * may not be used concurrently by multiple threads, as the context may contain
43 * thread unsafe attributes.
44 * </p>
45 *
46 * @since 4.0
47 */
48 public interface HttpContext {
49
50 /** The prefix reserved for use by HTTP components. "http." */
51 String RESERVED_PREFIX = "http.";
52
53 /**
54 * Obtains attribute with the given name.
55 *
56 * @param id the attribute name.
57 * @return attribute value, or {@code null} if not set.
58 */
59 Object getAttribute(String id);
60
61 /**
62 * Sets value of the attribute with the given name.
63 *
64 * @param id the attribute name.
65 * @param obj the attribute value.
66 */
67 void setAttribute(String id, Object obj);
68
69 /**
70 * Removes attribute with the given name from the context.
71 *
72 * @param id the attribute name.
73 * @return attribute value, or {@code null} if not set.
74 */
75 Object removeAttribute(String id);
76
77 }