Zend_Log_Writer_Stream sends log data to a PHP stream.

To write log data to the PHP output buffer, use the URL php://output. Alternatively, you can may like to send log data directly to a stream like STDERR (php://stderr).

<?php

$writer = new Zend_Log_Writer_Stream('php://output');
$logger = new Zend_Log($writer);

$logger->info('Informational message');

?>

To write data to a file, use one of the Filesystem URLs:

<?php

$writer = new Zend_Log_Writer_Stream('/path/to/logfile');
$logger = new Zend_Log($writer);

$logger->info('Informational message');

?>

By default, the stream opens in the append mode ("a"). To open it with a different mode, the Zend_Log_Writer_Stream constructor accepts an optional second parameter for the mode.

The constructor of Zend_Log_Writer_Stream also accepts an existing stream resource:

<?php

$stream = @fopen('/path/to/logfile', 'a', false);
if (! $stream) {
    throw new Exception('Failed to open stream');
}        

$writer = new Zend_Log_Writer_Stream($stream);
$logger = new Zend_Log($writer);

$logger->info('Informational message');

?>

You cannot specify the mode for existing stream resources. Doing so causes a Zend_Log_Exception to be thrown.

Zend_Log_Writer_Db writes log information to a database table using Zend_Db. The constructor of Zend_Log_Writer_Db receives a Zend_Db_Adapter instance, a table name, and a mapping of database columns to event data items:

<?php

$params = array ('host'     => '127.0.0.1',
                 'username' => 'malory',
                 'password' => '******',
                 'dbname'   => 'camelot');
$db = Zend_Db::factory('PDO_MYSQL', $params);

$columnMapping = array(array('lvl' => 'priority', 'msg' => 'message'));
$writer = new Zend_Log_Writer_Db($db, 'log_table_name', $columnMapping);

$logger = new Zend_Log($writer);

$logger->info('Informational message');

?>

The example above writes a single row of low data to the database table named log_table_name table. The database column named lvl receives the priority number and the column named msg receives the log messsage.

The Zend_Log_Writer_Null is a stub that does not write log data to anything. It is useful for disabling logging or stubbing out logging during tests:

<?php

$writer = new Zend_Log_Writer_Null;
$logger = new Zend_Log($writer);

// goes nowhere
$logger->info('Informational message');

?>

The Zend_Log_Writer_Mock is a very simple writer that records the raw data it receives in an array exposed as a public property.

<?php

$mock = new Zend_Log_Writer_Mock;
$logger = new Zend_Log($mock);

$logger->info('Informational message');

var_dump($mock->events[0]);

// Array
// (
//    [timestamp] => 2007-04-06T07:16:37-07:00
//    [message] => Informational message
//    [priority] => 6
//    [priorityName] => INFO
// )

?>

To clear the events logged by the mock, simply set $mock->events = array().

There is no composite Writer object. However, a Log instance can write to any number of Writers. To do this, use the addWriter() method:

<?php

$writer1 = new Zend_Log_Writer_Stream('/path/to/first/logfile');
$writer2 = new Zend_Log_Writer_Stream('/path/to/second/logfile');

$logger = new Zend_Log();
$logger->addWriter($writer1);
$logger->addWriter($writer2);

// goes to both writers
$logger->info('Informational message');      

?>