1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
|
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>DB_CHANNEL->send_request()</title>
<link rel="stylesheet" href="apiReference.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB C API Reference" />
<link rel="up" href="rep.html" title="Chapter 10. Replication Methods" />
<link rel="prev" href="dbchannel_send_msg.html" title="DB_CHANNEL->send_msg()" />
<link rel="next" href="dbchannel_set_timeout.html" title="DB_CHANNEL->set_timeout()" />
</head>
<body>
<div xmlns="" class="navheader">
<div class="libver">
<p>Library Version 12.1.6.1</p>
</div>
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DB_CHANNEL->send_request()</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
<th width="60%" align="center">Chapter 10.
Replication Methods
</th>
<td width="20%" align="right"> <a accesskey="n" href="dbchannel_set_timeout.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="dbchannel_send_request"></a>DB_CHANNEL->send_request()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db.h>
int
DB_CHANNEL->send_request(DB_CHANNEL *channel, DBT *request,
u_int32_t nrequest, DBT *response,
db_timeout_t timeout, u_int32_t flags); </pre>
<p>
The <code class="methodname">DB_CHANNEL->send_request()</code> method
sends a message on the message channel. The message is sent
synchronously; the method blocks waiting for a response before
returning. If a response is not received within the timeout value
configured for this request, this method returns with an error
condition.
</p>
<p>
If you do not want to block while waiting for a response from a remote
site, use the
<a class="xref" href="dbchannel_send_msg.html" title="DB_CHANNEL->send_msg()">DB_CHANNEL->send_msg()</a>
method.
</p>
<p>
The message sent by this method is received and handled at
remote sites using a message dispatch callback, which is configured
using the <a class="xref" href="repmgr_msg_dispatch.html" title="DB_ENV->repmgr_msg_dispatch()">DB_ENV->repmgr_msg_dispatch()</a>
method.
</p>
<p>
The <code class="methodname">DB_CHANNEL->send_request()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp3537880"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3534464"></a>request</h4>
</div>
</div>
</div>
<p>
Refers to an array of DBT handles. For more
information, see
<a class="xref" href="dbt.html" title="Chapter 4. The DBT Handle">
The DBT Handle
</a>.
</p>
<p>
Any flags provided to the DBT handles used in this
array are ignored.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3540952"></a>nrequest</h4>
</div>
</div>
</div>
<p>
Indicates how many elements are contained in the
<code class="literal">msg</code> array.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3533792"></a>response</h4>
</div>
</div>
</div>
<p>
Points to a single DBT handle, which is used to
receive the response from the remote site. By default, the
response is expected to be a single-part message. If
there is a possibility that the response could be a
multi-part message, specify <code class="literal">DB_MULTIPLE</code>
to this method's <span class="bold"><strong>flags</strong></span>
parameter.
</p>
<p>
The response DBT should specify one of the
following flags:
<code class="literal">DB_DBT_MALLOC</code>, <code class="literal">DB_DBT_REALLOC</code>,
or <code class="literal">DB_DBT_USERMEM</code>.
</p>
<p>
For more information on configuring and using
DBTs, see
<a class="xref" href="dbt.html" title="Chapter 4. The DBT Handle">
The DBT Handle
</a>.
</p>
<p>
Note that the response DBT can be empty. In this
way an application can send an acknowledgement even if
there is no other information that needs to be sent.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3542136"></a>timeout</h4>
</div>
</div>
</div>
<p>
Configures the amount of time that may elapse while this
method waits for a response from the remote site. If this
timeout period elapses without a response, this method
returns with an error condition.
</p>
<p>
The timeout value must be specified as an unsigned 32-bit
number of microseconds, limiting the maximum timeout to
roughly 71 minutes.
</p>
<p>
A timeout value of <code class="literal">0</code>
indicates that the channel's default timeout value should
be used. This default is configured using the
<a class="xref" href="dbchannel_set_timeout.html" title="DB_CHANNEL->set_timeout()">DB_CHANNEL->set_timeout()</a>
method.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3543680"></a>flags</h4>
</div>
</div>
</div>
<p>
This parameter must be set to either
<code class="literal">DB_MULTIPLE</code> or 0.
</p>
<p>
If there is a possibility that the response can consist of
multiple DBT handles, specify
<code class="literal">DB_MULTIPLE</code> to this parameter. In that
case, the response buffer is formatted for bulk
operations.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp3544760"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DB_CHANNEL->send_request()</code>
<span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3549168"></a>DB_BUFFER_SMALL</h4>
</div>
</div>
</div>
<p>
<code class="literal">DB_MULTIPLE</code> was not specified for the
response DBT, but the remote site sent a response
consisting of more than one DBT; or a buffer
supplied using <code class="literal">DB_DBT_USERMEM</code>
was not large enough to contain the message response.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3541368"></a>DB_NOSERVER</h4>
</div>
</div>
</div>
<p>
A message was sent to a remote site that has not
configured a message dispatch callback function.
Use the
<a class="xref" href="repmgr_msg_dispatch.html" title="DB_ENV->repmgr_msg_dispatch()">DB_ENV->repmgr_msg_dispatch()</a>
method at every site belonging to the replication group to configure a
message dispatch callback function.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp3520688"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If this method is called from a Base API application,
or if an invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp3551296"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>,
<a class="link" href="db_channel.html" title="The DB_CHANNEL Handle">DB_CHANNEL</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp3545648"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
</p>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="rep.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="dbchannel_set_timeout.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">DB_CHANNEL->send_msg() </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> DB_CHANNEL->set_timeout()</td>
</tr>
</table>
</div>
</body>
</html>
|
