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<div class="sect1" lang="en" xml:lang="en">
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<h2 class="title" style="clear: both"><a id="reptransport"></a>DbEnv::rep_set_transport()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::rep_set_transport(int envid,
int (*send)(DB_ENV *dbenv,
const Dbt *control, const Dbt *rec, const DbLsn *lsnp,
int envid, u_int32_t flags));</pre>
<p>
The <code class="methodname">DbEnv::rep_set_transport()</code> method initializes the communication
infrastructure for a database environment participating in a replicated application.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_transport()</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>
The <code class="methodname">DbEnv::rep_set_transport()</code> method configures operations
performed using the specified <a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle,
not all operations performed on the underlying database environment.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_transport()</code> method may be called at any time
during the life of the application.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_transport()</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="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Berkeley DB is not re-entrant. The callback function
for this method should not attempt to make
library calls (for example, to release locks or close open handles). Re-entering
Berkeley DB is not guaranteed to work correctly, and the results are undefined.
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1703770"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1704762"></a>envid</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>envid</strong></span> parameter is the local
environment's ID. It must be a non-negative integer and uniquely identify
this Berkeley DB database environment (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="id1704895"></a>send</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>send</strong></span> callback function is used to
transmit data using the replication application's communication
infrastructure. The parameters to <span class="bold"><strong>send</strong></span> are as follows:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">dbenv</code>
</p>
<p>
The <span class="bold"><strong>dbenv</strong></span> parameter is the enclosing
database environment handle.
</p>
</li>
<li>
<p>
<code class="literal">control</code>
</p>
<p>
The <span class="bold"><strong>control</strong></span> parameter is the first of
the two data elements to be transmitted by the <span class="bold"><strong>send</strong></span> function.
</p>
</li>
<li>
<p>
<code class="literal">rec</code>
</p>
<p>
The <span class="bold"><strong>rec</strong></span> parameter is the second of
the two data elements to be transmitted by the <span class="bold"><strong>send</strong></span> function.
</p>
</li>
<li>
<p>
<code class="literal">lsnp</code>
</p>
<p>
If the type of message to be sent has an LSN associated with it, then
the <span class="bold"><strong>lsnp</strong></span> parameter contains the LSN
of the record being sent. This LSN can be used to determine that
certain records have been processed successfully by clients.
</p>
</li>
<li>
<p>
<code class="literal">envid</code>
</p>
<p>
The <span class="bold"><strong>envid</strong></span> parameter is a positive
integer identifier that specifies the replication environment to which
the message should be sent (see <a href="../../programmer_reference/rep_id.html" class="olink">Replication environment IDs</a> for more
information).
</p>
<p><a id="transport_DB_EID_BROADCAST"></a>
The special identifier <code class="literal">DB_EID_BROADCAST</code> indicates that a message
should be broadcast to every environment in the replication group. The application
may use a true broadcast protocol or may send the message in sequence to each
machine with which it is in communication. In both cases, the sending site should
not be asked to process the message.
</p>
<p>
The special identifier
<a href="../../programmer_reference/rep_id.html#rep_id.DB_EID_INVALID" class="olink">DB_EID_INVALID</a>
indicates an invalid environment ID. This may be used to initialize
values that are subsequently checked for validity.
</p>
</li>
<li>
<p>
<code class="literal">flags</code>
</p>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or by bitwise inclusively <span class="bold"><strong>OR</strong></span>'ing
together one or more of the following values:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p><a id="transport_DB_REP_ANYWHERE"></a>
<code class="literal">DB_REP_ANYWHERE</code>
</p>
<p>
The message is a client request that can be satisfied by another
client as well as by the master.
</p>
</li>
<li>
<p><a id="transport_DB_REP_NOBUFFER"></a>
<code class="literal">DB_REP_NOBUFFER</code>
</p>
<p>
The record being sent should be transmitted immediately and not
buffered or delayed.
</p>
</li>
<li>
<p><a id="transport_DB_REP_PERMANENT"></a>
<code class="literal">DB_REP_PERMANENT</code>
</p>
<p>
The record being sent is critical for maintaining database integrity
(for example, the message includes a transaction commit). The
application should take appropriate action to enforce the reliability
guarantees it has chosen, such as waiting for acknowledgement from one
or more clients.
</p>
</li>
<li>
<p><a id="transport_DB_REP_REREQUEST"></a>
<code class="literal">DB_REP_REREQUEST</code>
</p>
<p>
The message is a client request that has already been made and to
which no response was received.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
It may sometimes be useful to pass application-specific data to the send
function; see <a href="../../programmer_reference/env_faq.html" class="olink">Environment FAQ</a>
for a discussion on how to do this.
</p>
<p>
The <span class="bold"><strong>send</strong></span> function must return 0 on success and non-zero on failure.
If the send function fails, the message being sent is necessary to maintain database integrity, and
the local log is not configured for synchronous flushing, the local log will be flushed; otherwise,
any error from the <span class="bold"><strong>send</strong></span> function will be ignored.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1704926"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::rep_set_transport()</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="id1705322"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
The method is called from a Replication Manager application; or 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="id1704691"></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="id1704564"></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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