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Release 5.2.28 on 6/10/2011
2011-09-13 17:44:24 +00:00
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<title>DbEnv::repmgr_msg_dispatch()</title>
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<p>Library Version 11.2.5.2</p>
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<th colspan="3" align="center">DbEnv::repmgr_msg_dispatch()</th>
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Replication Methods
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
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<h2 class="title" style="clear: both"><a id="repmgr_msg_dispatch"></a>DbEnv::repmgr_msg_dispatch()</h2>
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<pre class="programlisting">#include &lt;db_cxx.h&gt;
int
DbEnv::repmgr_msg_dispatch(
void (*msg_dispatch_fcn) (DbEnv *env, DbChannel *channel,
Dbt *request, u_int32_t nrequest,
u_int32_t cb_flags),
u_int32_t flags); </pre>
<p>
Sets the message dispatch function. This function is responsible
for receiving messages sent from remote sites using either the
<a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a>
or
<a class="xref" href="dbchannel_send_request.html" title="DbChannel::send_request()">DbChannel::send_request()</a>
methods. If the message received by this function was sent using the
<a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a>
method then no response is required. If the message was sent using the
<a class="xref" href="dbchannel_send_request.html" title="DbChannel::send_request()">DbChannel::send_request()</a>
method, then this function must send a response using the
<a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a>
method.
</p>
<p>
For best results, the
<code class="methodname">DbEnv::repmgr_msg_dispatch()</code> method should
be called before the Replication Manager has been started.
</p>
<p>
The <code class="methodname">DbEnv::repmgr_msg_dispatch()</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="id3664244"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3664233"></a>msg_dispatch_fcn</h4>
</div>
</div>
</div>
<p>
This parameter is the application-specific function used
to handle messages sent over Replication Manager message
channels. It takes four parameters:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">channel</code>
</p>
<p>
Provides the DbChannel to be used to send
a response back to the originator of the message.
If the message was sent by the remote site using
<a class="xref" href="dbchannel_send_request.html" title="DbChannel::send_request()">DbChannel::send_request()</a>
then this function should send a response back to
the originator using the channel provided on this
parameter. The message should be sent by calling
<a class="xref" href="dbchannel_send_msg.html" title="DbChannel::send_msg()">DbChannel::send_msg()</a>
exactly once.
</p>
<p>
This channel is valid only during the current
invocation of the dispatch function; it is
destroyed when the dispatch function returns. The
application may not save a copy of the pointer and
use it later elsewhere. Methods that do not make
sense in the context of a message dispatch
function (such as
<a class="xref" href="dbchannel_send_request.html" title="DbChannel::send_request()">DbChannel::send_request()</a>
and
<a class="xref" href="dbchannel_close.html" title="DbChannel::close()">DbChannel::close()</a>)
will be rejected with <code class="literal">EINVAL</code>.
</p>
</li>
<li>
<p>
<code class="literal">request</code>
</p>
<p>
Array of Dbts containing the message
received from the remote site.
</p>
</li>
<li>
<p>
<code class="literal">nrequest</code>
</p>
<p>
Specifies the number of elements in the
<code class="literal">request</code> array.
</p>
</li>
<li>
<p>
<code class="literal">cb_flags</code>
</p>
<p>
This flag is
<code class="literal">DB_REPMGR_NEED_RESPONSE</code> if the
message requires a response. Otherwise, it is
<code class="literal">0</code>.
</p>
</li>
</ul>
</div>
<p>
This function does not return a value. If the function
encounters an error, you can reflect the error back to
the originator of the message by formatting an error
message of your own design into the response.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3664455"></a>flags</h4>
</div>
</div>
</div>
<p>
This parameter is currently unused, and must be
set to 0.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id3664360"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::repmgr_msg_dispatch()</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="id3664414"></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="id3664540"></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">
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<div>
<h3 class="title"><a id="id3664487"></a>See Also</h3>
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<p>
<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
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