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<?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">
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<title>DbChannel::send_request()</title>
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<div class="libver">
<p>Library Version 11.2.5.3</p>
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<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">DbChannel::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 11.
Replication Methods
</th>
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</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>DbChannel::send_request()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbChannel::send_request(Dbt *request, u_int32_t nrequest,
Dbt *response, db_timeout_t timeout,
u_int32_t flags);</pre>
<p>
The <code class="methodname">DbChannel::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="DbChannel::send_msg()">DbChannel::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="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
method.
</p>
<p>
The <code class="methodname">DbChannel::send_request()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9344800"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9345184"></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="idp9340936"></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="idp9344040"></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="idp9332504"></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="DbChannel::set_timeout()">DbChannel::set_timeout()</a>
method.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9327720"></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="idp9348672"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbChannel::send_request()</code>
<span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or 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="idp9353168"></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="idp9355624"></a>DB_NOSERVER</h4>
</div>
</div>
</div>
<p>
A message was sent to a remote site that has not
configured a message dispatch call-back function.
Use the
<a class="xref" href="repmgr_msg_dispatch.html" title="DbEnv::repmgr_msg_dispatch()">DbEnv::repmgr_msg_dispatch()</a>
method at every site belonging to the replication group to configure a
message dispatch call-back function.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9334448"></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="idp9352088"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9345448"></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>
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