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 @Override
48 void close() throws IOException;
49
50 /**
51 * Checks if this connection is open.
52 * @return true if it is open, false if it is closed.
53 */
54 boolean isOpen();
55
56 /**
57 * Checks whether this connection has gone down.
58 * Network connections may get closed during some time of inactivity
59 * for several reasons. The next time a read is attempted on such a
60 * connection it will throw an IOException.
61 * This method tries to alleviate this inconvenience by trying to
62 * find out if a connection is still usable. Implementations may do
63 * that by attempting a read with a very small timeout. Thus this
64 * method may block for a small amount of time before returning a result.
65 * It is therefore an <i>expensive</i> operation.
66 *
67 * @return {@code true} if attempts to use this connection are
68 * likely to succeed, or {@code false} if they are likely
69 * to fail and this connection should be closed
70 */
71 boolean isStale();
72
73 /**
74 * Sets the socket timeout value.
75 *
76 * @param timeout timeout value in milliseconds
77 */
78 void setSocketTimeout(int timeout);
79
80 /**
81 * Returns the socket timeout value.
82 *
83 * @return positive value in milliseconds if a timeout is set,
84 * {@code 0} if timeout is disabled or {@code -1} if
85 * timeout is undefined.
86 */
87 int getSocketTimeout();
88
89 /**
90 * Force-closes this connection.
91 * This is the only method of a connection which may be called
92 * from a different thread to terminate the connection.
93 * This method will not attempt to flush the transmitter's
94 * internal buffer prior to closing the underlying socket.
95 */
96 void shutdown() throws IOException;
97
98 /**
99 * Returns a collection of connection metrics.
100 *
101 * @return HttpConnectionMetrics
102 */
103 HttpConnectionMetrics getMetrics();
104
105 }