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===============
 Horde_History
===============

Horde_History is a library to track and find change events for arbitrary resources. Histories can be saved to SQL or MongoDb, a Composite backend also exists.
Possible use cases are sync protocols, undo/rewind features or human consumable history information. The Horde_Activesync implementation uses Horde_Histories to track create/delete/update events of syncable items.

---------------
 General Usage
---------------

Create an implementation of the Horde_History class and fulfill its dependencies
::
$history = new Horde_History_Sql($username, Horde_Db_Adapter $db);

Log events related to a $guid identifying the resource tracked

::

 $history->log('room1:shelf1:item100', array(
         'who' => 'someuser', // defaults to the user provided at construction of the object
         'action' => 'create',
    ));
 
 $history->log('room1:shelf1:item100', array(
         'who' => 'someotheruser', // defaults to the user provided at construction of the object
         'action' => 'modify',
         'ts' => 1287666089, // Defaults to now,
         'desc' => 'Human Readble Description'
    ));
 
 $history->log('room1:shelf1:item100', array('action' => 'delete'));

Retrieve the whole history of some guid
::

 $log = $history->getHistory("room1:shelf1:item100"); // returns a Horde_History_Log object

Retrieve the list of history items compared to a certain timestamp

::

 $ids = $history->getByTimestamp('>=', 1287666089); // returns an array of integers

Or add filters
::

 $ids = $history->getByTimestamp('>=', 1287666089, array(
     array('action', '==', 'delete')
     )
 ); // returns an array of integers

Get events between some changesets, allowing filters

::

 $ids = $history->getByModSeq(1287, 1305);
  // returns an array of integers
 
 $ids = $history->getByModSeq(1287, 1305, array(array('action', '==', 'create')));
  // returns an array of integers

Limit to events within a parent resource
::

 $ids = $history->getByModSeq(12876, 1305, array(), 'room1:shelf1');
  // returns an array of integers
 
 $ids = $history->getByModSeq(12876, 1305, array(array('action', '==', 'create')), 'room1:shelf1');
  // returns an array of integers

Get the last time a certain action happened to a resource

::

 $ts = $history->getActionTimestamp('room1:shelf1', 'createitem');

Remove all histories for a certain parent guid, for example because a collection gets deleted

::

 $history->removeByParent('room12');

Or remove a list of guids from history (not including child resources)

::

 $history->removeByNames(array('room12:shelf1', 'room12:shelf2', 'room12:shelf3'));

Get the last change to any child guid below a parent guid
::

 $modseq = $history->getHighestModSeq('room1');

Get the latest entry for a guid by modseq
::

 $entry = $history->getLatestEntry('room1');

or by timestamp
::

 $entry = $history->getLatestEntry('room1', true);

---------------------------------
 Usage inside Horde applications
---------------------------------

Use the Injector to get a configured instance of Horde_Core_History.

::

 $history = $GLOBALS['injector']->getInstance('Horde_History');

Horde_Core_History wraps Horde_History instances. It defaults to the logged in user and delegates most calls to the actual backends.

----

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