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<div class="sect1" lang="en" xml:lang="en">
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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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<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="idp53870984"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp53870616"></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="idp53865680"></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="idp53855328"></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="idp53858888"></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="idp53878992"></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="idp53880072"></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="idp53884376"></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="idp53885216"></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="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 call-back function.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp53856712"></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="idp53886672"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp53870120"></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>
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