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 send log data directly to a stream like STDERR (php://stderr).

$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:

$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:

$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:

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

$columnMapping = 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 log 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 message.

Zend_Log_Writer_Firebug sends log data to the Firebug Console.

All data is sent via the Zend_Wildfire_Channel_HttpHeaders component which uses HTTP headers to ensure the page content is not disturbed. Debugging AJAX requests that require clean JSON and XML responses is possible with this approach.

Requirements:

// Place this in your bootstrap file before dispatching your front controller
$writer = new Zend_Log_Writer_Firebug();
$logger = new Zend_Log($writer);

// Use this in your model, view and controller files
$logger->log('This is a log message!', Zend_Log::INFO);

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

$request = new Zend_Controller_Request_Http();
$response = new Zend_Controller_Response_Http();
$channel = Zend_Wildfire_Channel_HttpHeaders::getInstance();
$channel->setRequest($request);
$channel->setResponse($response);

// Start output buffering
ob_start();

// Now you can make calls to the logger

$logger->log('This is a log message!', Zend_Log::INFO);

// Flush log data to browser
$channel->flush();
$response->sendHeaders();

$logger->addPriority('FOO', 8);
$writer->setPriorityStyle(8, 'TRACE');
$logger->foo('Foo Message');

$writer->setDefaultPriorityStyle('TRACE');

$exception = new Zend_Exception('Test exception');
$logger->err($exception);

$writer->setPriorityStyle(8, 'TABLE');
$logger->addPriority('TABLE', 8);

$table = array('Summary line for the table',
             array(
                 array('Column 1', 'Column 2'),
                 array('Row 1 c 1',' Row 1 c 2'),
                 array('Row 2 c 1',' Row 2 c 2')
             )
            );
$logger->table($table);

Zend_Log_Writer_Mail writes log entries in an email message by using Zend_Mail. The Zend_Log_Writer_Mail constructor takes a Zend_Mail object, and an optional Zend_Layout object.

The primary use case for Zend_Log_Writer_Mail is notifying developers, systems administrators, or any concerned parties of errors that might be occurring with PHP-based scripts. Zend_Log_Writer_Mail was born out of the idea that if something is broken, a human being needs to be alerted of it immediately so they can take corrective action.

Basic usage is outlined below:

$mail = new Zend_Mail();
$mail->setFrom('errors@example.org')
     ->addTo('project_developers@example.org');

$writer = new Zend_Log_Writer_Mail($mail);

// Set subject text for use; summary of number of errors is appended to the
// subject line before sending the message.
$writer->setSubjectPrependText('Errors with script foo.php');

// Only email warning level entries and higher.
$writer->addFilter(Zend_Log::WARN);

$log = new Zend_Log();
$log->addWriter($writer);

// Something bad happened!
$log->error('unable to connect to database');

// On writer shutdown, Zend_Mail::send() is triggered to send an email with
// all log entries at or above the Zend_Log filter level.

Zend_Log_Writer_Mail will render the email body as plain text by default.

One email is sent containing all log entries at or above the filter level. For example, if warning-level entries an up are to be emailed, and two warnings and five errors occur, the resulting email will contain a total of seven log entries.

$mail = new Zend_Mail();
$mail->setFrom('errors@example.org')
     ->addTo('project_developers@example.org');
// Note that a subject line is not being set on the Zend_Mail instance!

// Use a simple Zend_Layout instance with its defaults.
$layout = new Zend_Layout();

// Create a formatter that wraps the entry in a listitem tag.
$layoutFormatter = new Zend_Log_Formatter_Simple(
    '<li>' . Zend_Log_Formatter_Simple::DEFAULT_FORMAT . '</li>'
);

$writer = new Zend_Log_Writer_Mail($mail, $layout);

// Apply the formatter for entries as rendered with Zend_Layout.
$writer->setLayoutFormatter($layoutFormatter);
$writer->setSubjectPrependText('Errors with script foo.php');
$writer->addFilter(Zend_Log::WARN);

$log = new Zend_Log();
$log->addWriter($writer);

// Something bad happened!
$log->error('unable to connect to database');

// On writer shutdown, Zend_Mail::send() is triggered to send an email with
// all log entries at or above the Zend_Log filter level. The email will
// contain both plain text and HTML parts.

Zend_Log_Writer_Syslog writes log entries to the system log (syslog). Internally, it proxies to PHP's openlog(), closelog(), and syslog() functions.

One useful case for Zend_Log_Writer_Syslog is for aggregating logs from clustered machines via the system log functionality. Many systems allow remote logging of system events, which allows system administrators to monitor a cluster of machines from a single log file.

By default, all syslog messages generated are prefixed with the string "Zend_Log". You may specify a different "application" name by which to identify such log messages by either passing the application name to the constructor or the application accessor:

// At instantiation, pass the "application" key in the options:
$writer = new Zend_Log_Writer_Syslog(array('application' => 'FooBar'));

// Any other time:
$writer->setApplicationName('BarBaz');

The system log also allows you to identify the "facility," or application type, logging the message; many system loggers will actually generate different log files per facility, which again aids administrators monitoring server activity.

You may specify the log facility either in the constructor or via an accessor. It should be one of the openlog() constants defined on the openlog() manual page.

// At instantiation, pass the "facility" key in the options:
$writer = new Zend_Log_Writer_Syslog(array('facility' => LOG_AUTH));

// Any other time:
$writer->setFacility(LOG_USER);

When logging, you may continue to use the default Zend_Log priority constants; internally, they are mapped to the appropriate syslog() priority constants.

Zend_Log_Writer_ZendMonitor allows you to log events via Zend Server's Monitor API. This allows you to aggregate log messages for your entire application environment in a single location. Internally, it simply uses the monitor_custom_event() function from the Zend Monitor API.

One particularly useful feature of the Monitor API is that it allows you to specify arbitrary custom information alongside the log message. For instance, if you wish to log an exception, you can log not just the exception message, but pass the entire exception object to the function, and then inspect the object within the Zend Server event monitor.

Instantiating the ZendMonitor log writer is trivial:

$writer = new Zend_Log_Writer_ZendMonitor();
$log    = new Zend_Log($writer);

Then, simply log messages as usual:

$log->info('This is a message');

If you want to specify additional information to log with the event, pass that information in a second parameter:

$log->info('Exception occurred', $e);

The second parameter may be a scalar, object, or array; if you need to pass multiple pieces of information, the best way to do so is to pass an associative array.

$log->info('Exception occurred', array(
    'request'   => $request,
    'exception' => $e,
));

Within Zend Server, your event is logged as a "custom event". From the "Monitor" tab, select the "Events" sub-item, and then filter on "Custom" to see custom events.

Events in Zend Server's Monitor dashboard

In this screenshot, the first two events listed are custom events logged via the ZendMonitor log writer. You may then click on an event to view all information related to it.

Event detail in Zend Server's Monitor

Clicking on the "Custom" sub tab will detail any extra information you logged by passing the second argument to the logging method. This information will be logged as the info subkey; you can see that the request object was logged in this example.

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:

$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.

$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:

$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');