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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<title>DbEnv::rep_process_message()</title>
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<th colspan="3" align="center">DbEnv::rep_process_message()</th>
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<th width="60%" align="center">Chapter 11.
Replication Methods
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="repmessage"></a>DbEnv::rep_process_message()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::rep_process_message(Dbt *control, Dbt *rec, int envid,
DbLsn *ret_lsnp)</pre>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method processes an incoming
replication message sent by a member of the replication group to the
local database environment.
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method is not called by most
replication applications. It should only be called by Base API applications
implementing their own network transport layer, explicitly holding
replication group elections and handling replication messages outside
of the Replication Manager framework.
</p>
<p>
For implementation reasons, all incoming replication messages must be
processed using the same <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle. It is not
required that a single thread of control process all messages, only
that all threads of control processing messages use the same handle.
</p>
<p>
Before calling this method, the enclosing database environment must
already have been opened by calling the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method and must
already have been configured to send replication messages by
calling the <a class="xref" href="reptransport.html" title="DbEnv::rep_set_transport()">DbEnv::rep_set_transport()</a>
method.
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method has additional return
values:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="repmsg_DB_REP_DUPMASTER"></a>
<span class="bold"><strong>DB_REP_DUPMASTER</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_DUPMASTER</code> if the replication group has more than one
master. The application should reconfigure itself as a client by calling the
<a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a> method, and then call for an
election by calling <a class="xref" href="repelect.html" title="DbEnv::rep_elect()">DbEnv::rep_elect()</a>.
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_HOLDELECTION"></a>
<span class="bold"><strong>DB_REP_HOLDELECTION</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_HOLDELECTION</code> if an election is needed. The application
should call for an election by calling
<a class="xref" href="repelect.html" title="DbEnv::rep_elect()">DbEnv::rep_elect()</a>.
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_IGNORE"></a>
<span class="bold"><strong>DB_REP_IGNORE</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_IGNORE</code> if this message cannot be processed. This is an
indication that this message is irrelevant to the current replication state (for
example, an old message from a previous generation arrives and is processed late).
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_ISPERM"></a>
<span class="bold"><strong>DB_REP_ISPERM</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_ISPERM</code> if processing this message results in the
processing of records that are permanent. The maximum LSN of the permanent records
stored is returned.
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_JOIN_FAILURE"></a>
<span class="bold"><strong>DB_REP_JOIN_FAILURE</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_JOIN_FAILURE</code> if a new master has been chosen but the
client is unable to synchronize with the new master. This is possibly because the client
has turned off automatic internal initialization by setting the
<a class="link" href="repconfig.html#config_DB_REP_CONF_AUTOINIT">DB_REP_CONF_AUTOINIT</a>
flag to <code class="literal">0</code>.
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_NEWSITE"></a>
<span class="bold"><strong>DB_REP_NEWSITE</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_NEWSITE</code> if the system received contact information from a
new environment. The <span class="bold"><strong>rec</strong></span> parameter contains the
opaque data specified to the <a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a>
<span class="bold"><strong>cdata</strong></span> parameter. The application should
take whatever action is needed to establish a communication channel with this new
environment.
</p>
</li>
<li>
<p><a id="repmsg_DB_REP_NOTPERM"></a>
<span class="bold"><strong>DB_REP_NOTPERM</strong></span>
</p>
<p>
The <code class="methodname">DbEnv::rep_process_message()</code> method will return
<code class="literal">DB_REP_NOTPERM</code> if a message carrying a
<a class="link" href="reptransport.html#transport_DB_REP_PERMANENT">DB_REP_PERMANENT</a>
flag was processed successfully, but was not written to disk. The LSN of this
record is returned. The application should take whatever action is deemed
necessary to retain its recoverability characteristics.
</p>
</li>
</ul>
</div>
<p>
Unless otherwise specified, the <code class="methodname">DbEnv::rep_process_message()</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="idp9527384"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9526736"></a>control</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>control</strong></span> parameter should
reference a copy of the <span class="bold"><strong>control</strong></span>
parameter specified by Berkeley DB on the sending environment.
See the <a class="xref" href="reptransport.html" title="DbEnv::rep_set_transport()">DbEnv::rep_set_transport()</a> method for more information.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9541904"></a>rec</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>rec</strong></span> parameter should reference a
copy of the <span class="bold"><strong>rec</strong></span> parameter specified
by Berkeley DB on the sending environment.
See the <a class="xref" href="reptransport.html" title="DbEnv::rep_set_transport()">DbEnv::rep_set_transport()</a> method for more information.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9543352"></a>envid</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>envid</strong></span> parameter should contain
the local identifier that corresponds to the environment that sent the
message to be processed (see <a href="../../programmer_reference/rep_id.html" class="olink">Replication environment IDs</a> for more
information).
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp9546032"></a>ret_lsnp</h4>
</div>
</div>
</div>
<p>
If <code class="methodname">DbEnv::rep_process_message()</code> method returns
<code class="literal">DB_REP_NOTPERM</code> then the
<span class="bold"><strong>ret_lsnp</strong></span> parameter will contain the log sequence
number of this permanent log message that could not be written to disk. If
<code class="methodname">DbEnv::rep_process_message()</code> method returns
<code class="literal">DB_REP_ISPERM</code> then the
<span class="bold"><strong>ret_lsnp</strong></span> parameter will contain largest log
sequence number of the permanent records that are now written to disk as a
result of processing this message. In all other cases the value of
<span class="bold"><strong>ret_lsnp</strong></span> is undefined.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp9511800"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::rep_process_message()</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="idp9554464"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the database environment was not already configured to
communicate with a replication group by a call to
<a class="xref" href="reptransport.html" title="DbEnv::rep_set_transport()">DbEnv::rep_set_transport()</a>;
if the database environment was not already opened;
if this method is called from a Replication Manager
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="idp9533976"></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="idp9529376"></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>
</div>
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