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309 lines
12 KiB
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DB_CHANNEL->send_request()</title>
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<link rel="up" href="rep.html" title="Chapter 10. Replication Methods" />
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<link rel="prev" href="dbchannel_send_msg.html" title="DB_CHANNEL->send_msg()" />
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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">DB_CHANNEL->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 10.
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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>DB_CHANNEL->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.h>
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int
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DB_CHANNEL->send_request(DB_CHANNEL *channel, DBT *request,
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u_int32_t nrequest, DBT *response,
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db_timeout_t timeout, u_int32_t flags); </pre>
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<p>
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The <code class="methodname">DB_CHANNEL->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="DB_CHANNEL->send_msg()">DB_CHANNEL->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="DB_ENV->repmgr_msg_dispatch()">DB_ENV->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">DB_CHANNEL->send_request()</code> <span>
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<span>
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method returns a non-zero error value on failure and 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="id3744558"></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="id3744497"></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="id3744417"></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="id3744407"></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="id3744621"></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="DB_CHANNEL->set_timeout()">DB_CHANNEL->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="id3744646"></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="id3744664"></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">DB_CHANNEL->send_request()</code>
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<span>
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<span>
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method may fail and return one 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="id3744737"></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="id3744750"></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="DB_ENV->repmgr_msg_dispatch()">DB_ENV->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="id3744270"></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="id3744772"></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 DB_ENV Handle">DB_ENV</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="id3744491"></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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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="dbchannel_send_msg.html">Prev</a> </td>
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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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<td width="40%" align="right"> <a accesskey="n" href="dbchannel_set_timeout.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DB_CHANNEL->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"> DB_CHANNEL->set_timeout()</td>
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</tr>
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</table>
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</body>
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</html>
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