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;
29
30 import java.io.Closeable;
31 import java.io.IOException;
32
33 /**
34 * A generic HTTP connection, useful on client and server side.
35 *
36 * @since 4.0
37 */
38 public interface HttpConnection extends Closeable {
39
40 /**
41 * Closes this connection gracefully.
42 * This method will attempt to flush the internal output
43 * buffer prior to closing the underlying socket.
44 * This method MUST NOT be called from a different thread to force
45 * shutdown of the connection. Use {@link #shutdown shutdown} instead.
46 */
47 void close() throws IOException;
48
49 /**
50 * Checks if this connection is open.
51 * @return true if it is open, false if it is closed.
52 */
53 boolean isOpen();
54
55 /**
56 * Checks whether this connection has gone down.
57 * Network connections may get closed during some time of inactivity
58 * for several reasons. The next time a read is attempted on such a
59 * connection it will throw an IOException.
60 * This method tries to alleviate this inconvenience by trying to
61 * find out if a connection is still usable. Implementations may do
62 * that by attempting a read with a very small timeout. Thus this
63 * method may block for a small amount of time before returning a result.
64 * It is therefore an <i>expensive</i> operation.
65 *
66 * @return <code>true</code> if attempts to use this connection are
67 * likely to succeed, or <code>false</code> if they are likely
68 * to fail and this connection should be closed
69 */
70 boolean isStale();
71
72 /**
73 * Sets the socket timeout value.
74 *
75 * @param timeout timeout value in milliseconds
76 */
77 void setSocketTimeout(int timeout);
78
79 /**
80 * Returns the socket timeout value.
81 *
82 * @return positive value in milliseconds if a timeout is set,
83 * <code>0</code> if timeout is disabled or <code>-1</code> if
84 * timeout is undefined.
85 */
86 int getSocketTimeout();
87
88 /**
89 * Force-closes this connection.
90 * This is the only method of a connection which may be called
91 * from a different thread to terminate the connection.
92 * This method will not attempt to flush the transmitter's
93 * internal buffer prior to closing the underlying socket.
94 */
95 void shutdown() throws IOException;
96
97 /**
98 * Returns a collection of connection metrics.
99 *
100 * @return HttpConnectionMetrics
101 */
102 HttpConnectionMetrics getMetrics();
103
104 }