130 lines
6.6 KiB
HTML
130 lines
6.6 KiB
HTML
<!--$Id: rep_transport.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<!--See the file LICENSE for redistribution information.-->
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<html>
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<head>
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<title>Berkeley DB: DbEnv::rep_set_transport</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b>DbEnv::rep_set_transport</b>
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</td>
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<td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>
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#include <db_cxx.h>
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<p>
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int
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DbEnv::rep_set_transport(int envid,
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int (*send)(DB_ENV *dbenv,
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const Dbt *control, const Dbt *rec, const DbLsn *lsnp,
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int envid, u_int32_t flags));
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DbEnv::rep_set_transport</b>
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<p>The DbEnv::rep_set_transport method initializes the communication infrastructure
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for a database environment participating in a replicated application.</p>
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<p>The DbEnv::rep_set_transport method is not called by most replication
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applications. It should only be called by applications implementing
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their own network transport layer, explicitly holding replication group
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elections and handling replication messages outside of the replication
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manager framework.</p>
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<p>The DbEnv::rep_set_transport method configures operations performed using the specified
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<a href="../api_cxx/env_class.html">DbEnv</a> handle, not all operations performed on the underlying
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database environment.</p>
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<p>The DbEnv::rep_set_transport method may be called at any time during the life of the
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application.</p>
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<p>The DbEnv::rep_set_transport method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>envid</b><ul compact><li>The <b>envid</b> parameter is the local environment's ID. It must be
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a non-negative integer and uniquely identify this Berkeley DB database environment
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(see <a href="../ref/rep/id.html">Replication environment IDs</a> for more
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information).</ul>
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<b>send</b><ul compact><li>The <b>send</b> callback function is used to transmit data using the
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replication application's communication infrastructure. The parameters
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to <b>send</b> are as follows:
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<br>
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<b><b>dbenv</b></b><ul compact><li>The <b>dbenv</b> parameter is the enclosing database environment handle.</ul>
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<b><b>control</b></b><ul compact><li>The <b>control</b> parameter is the first of the two data elements to be
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transmitted by the <b>send</b> function.</ul>
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<b><b>rec</b></b><ul compact><li>The <b>rec</b> parameter is the second of the two data elements to be
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transmitted by the <b>send</b> function.</ul>
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<b><b>lsnp</b></b><ul compact><li>If the type of message to be sent has an LSN associated with it, then
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the <b>lsnp</b> parameter contains the LSN of the record being sent.
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This LSN can be used to determine that certain records have been
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processed successfully by clients.</ul>
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<b><b>envid</b></b><ul compact><li>The <b>envid</b> parameter is a positive integer identifier that
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specifies the replication environment to which the message should be
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sent (see <a href="../ref/rep/id.html">Replication environment IDs</a> for
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more information).
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<p>The special identifier DB_EID_BROADCAST indicates that a message
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should be broadcast to every environment in the replication group. The
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application may use a true broadcast protocol or may send the message
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in sequence to each machine with which it is in communication. In both
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cases, the sending site should not be asked to process the message.</p>
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<p>The special identifier <a href="../ref/rep/id.html#DB_EID_INVALID">DB_EID_INVALID</a> indicates an invalid
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environment ID. This may be used to initialize values that are
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subsequently checked for validity.</p></ul>
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<b><b>flags</b></b><ul compact><li>The <b>flags</b> parameter must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one
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or more of the following values:
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<br>
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<b><a name="DB_REP_ANYWHERE">DB_REP_ANYWHERE</a></b><ul compact><li>The message is a client request that can be satisfied by another client
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as well as by the master.</ul>
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<b><a name="DB_REP_NOBUFFER">DB_REP_NOBUFFER</a></b><ul compact><li>The record being sent should be transmitted immediately and not buffered
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or delayed.</ul>
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<b><a name="DB_REP_PERMANENT">DB_REP_PERMANENT</a></b><ul compact><li>The record being sent is critical for maintaining database integrity
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(for example, the message includes a transaction commit). The
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application should take appropriate action to enforce the reliability
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guarantees it has chosen, such as waiting for acknowledgement from one
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or more clients.</ul>
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<b><a name="DB_REP_REREQUEST">DB_REP_REREQUEST</a></b><ul compact><li>The message is a client request that has already been made and to which
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no response was received.</ul>
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<br></ul>
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<br>
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<p>It may sometimes be useful to pass application-specific data to the
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<b>send</b> function; see <a href="../ref/env/faq.html">Environment
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FAQ</a> for a discussion on how to do this.</p>
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<p>The <b>send</b> function must return 0 on success and non-zero on
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failure. If the <b>send</b> function fails, the message being sent is
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necessary to maintain database integrity, and the local log is not
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configured for synchronous flushing, the local log will be flushed;
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otherwise, any error from the <b>send</b> function will be ignored.</p>
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<p>Berkeley DB is not re-entrant. Callback functions should not attempt to make
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library calls (for example, to release locks or close open handles).
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Re-entering Berkeley DB is not guaranteed to work correctly, and the results
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are undefined.</p></ul>
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<br>
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<br><b>Errors</b>
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<p>The DbEnv::rep_set_transport method
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may fail and throw
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<a href="../api_cxx/except_class.html">DbException</a>,
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encapsulating one of the following non-zero errors, or return one of
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the following non-zero errors:</p>
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<br>
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<b>EINVAL</b><ul compact><li>An
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invalid flag value or parameter was specified.</ul>
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<br>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_cxx/env_class.html">DbEnv</a>
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<br><b>See Also</b>
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<a href="../api_cxx/rep_list.html">Replication and Related Methods</a>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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