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314 lines
12 KiB
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbChannel::send_request()</title>
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<link rel="stylesheet" href="apiReference.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C++ API Reference" />
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<link rel="up" href="rep.html" title="Chapter 11. Replication Methods" />
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<link rel="prev" href="dbchannel_send_msg.html" title="DbChannel::send_msg()" />
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<link rel="next" href="dbchannel_set_timeout.html" title="DbChannel::set_timeout()" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DbChannel::send_request()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 11.
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Replication Methods
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="dbchannel_set_timeout.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="dbchannel_send_request"></a>DbChannel::send_request()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db_cxx.h>
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int
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DbChannel::send_request(Dbt *request, u_int32_t nrequest,
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Dbt *response, db_timeout_t timeout,
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u_int32_t flags);</pre>
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<p>
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The <code class="methodname">DbChannel::send_request()</code> method
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sends a message on the message channel. The message is sent
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synchronously; the method blocks waiting for a response before
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returning. If a response is not received within the timeout value
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configured for this request, this method returns with an error
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condition.
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</p>
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<p>
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If you do not want to block while waiting for a response from a remote
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site, use the
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<a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a>
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method.
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</p>
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<p>
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The message sent by this method is received and handled at
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remote sites using a message dispatch callback, which is configured
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using the <a class="xref" href="repmgr_msg_dispatch.html" title="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
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method.
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</p>
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<p>
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The <code class="methodname">DbChannel::send_request()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</span>
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</span>
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</p>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3655524"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655513"></a>request</h4>
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</div>
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</div>
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</div>
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<p>
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Refers to an array of Dbt handles. For more
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information, see
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<a class="xref" href="dbt.html" title="Chapter 4. The Dbt Handle">
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The Dbt Handle
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</a>.
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</p>
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<p>
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Any flags provided to the Dbt handles used in this
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array are ignored.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655556"></a>nrequest</h4>
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</div>
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</div>
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</div>
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<p>
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Indicates how many elements are contained in the
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<code class="literal">msg</code> array.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655329"></a>response</h4>
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</div>
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</div>
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</div>
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<p>
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Points to a single Dbt handle, which is used to
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receive the response from the remote site. By default, the
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response is expected to be a single-part message. If
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there is a possibility that the response could be a
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multi-part message, specify <code class="literal">DB_MULTIPLE</code>
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to this method's <span class="bold"><strong>flags</strong></span>
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parameter.
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</p>
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<p>
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The response Dbt should specify one of the
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following flags:
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<code class="literal">DB_DBT_MALLOC</code>, <code class="literal">DB_DBT_REALLOC</code>,
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or <code class="literal">DB_DBT_USERMEM</code>.
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</p>
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<p>
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For more information on configuring and using
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Dbts, see
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<a class="xref" href="dbt.html" title="Chapter 4. The Dbt Handle">
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The Dbt Handle
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</a>.
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</p>
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<p>
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Note that the response Dbt can be empty. In this
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way an application can send an acknowledgement even if
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there is no other information that needs to be sent.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655428"></a>timeout</h4>
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</div>
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</div>
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</div>
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<p>
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Configures the amount of time that may elapse while this
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method waits for a response from the remote site. If this
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timeout period elapses without a response, this method
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returns with an error condition.
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</p>
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<p>
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The timeout value must be specified as an unsigned 32-bit
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number of microseconds, limiting the maximum timeout to
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roughly 71 minutes.
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</p>
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<p>
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A timeout value of <code class="literal">0</code>
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indicates that the channel's default timeout value should
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be used. This default is configured using the
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<a class="xref" href="dbchannel_set_timeout.html" title="DbChannel::set_timeout()">DbChannel::set_timeout()</a>
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method.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655563"></a>flags</h4>
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</div>
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</div>
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</div>
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<p>
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This parameter must be set to either
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<code class="literal">DB_MULTIPLE</code> or 0.
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</p>
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<p>
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If there is a possibility that the response can consist of
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multiple Dbt handles, specify
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<code class="literal">DB_MULTIPLE</code> to this parameter. In that
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case, the response buffer is formatted for bulk
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operations.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3655580"></a>Errors</h3>
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</div>
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</div>
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</div>
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<p>
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The <code class="methodname">DbChannel::send_request()</code>
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<span>
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<span>
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method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
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exception, encapsulating one of the following non-zero errors, or return one
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of the following non-zero errors:
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</span>
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</span>
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</p>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655657"></a>DB_BUFFER_SMALL</h4>
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</div>
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</div>
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</div>
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<p>
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<code class="literal">DB_MULTIPLE</code> was not specified for the
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response Dbt, but the remote site sent a response
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consisting of more than one Dbt; or a buffer
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supplied using <code class="literal">DB_DBT_USERMEM</code>
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was not large enough to contain the message response.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655213"></a>DB_NOSERVER</h4>
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</div>
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</div>
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</div>
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<p>
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A message was sent to a remote site that has not
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configured a message dispatch call-back function.
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Use the
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<a class="xref" href="repmgr_msg_dispatch.html" title="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
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method at every site belonging to the replication group to configure a
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message dispatch call-back function.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3655344"></a>EINVAL</h4>
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</div>
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</div>
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</div>
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<p>
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If this method is called from a Base API application,
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or if an invalid flag value or parameter was specified.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3655639"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3655527"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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|||
|
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<table width="100%" summary="Navigation footer">
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|||
|
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<tr>
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|||
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<td width="40%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
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|||
|
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<td width="20%" align="center">
|
|||
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<a accesskey="u" href="rep.html">Up</a>
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</td>
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|||
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<td width="40%" align="right"> <a accesskey="n" href="dbchannel_set_timeout.html">Next</a></td>
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|||
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DbChannel::send_msg() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DbChannel::set_timeout()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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