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File: README.txt
Role: Documentation
Content type: text/plain
Description: README
Class: AJAX Locking
Lock server side resources from AJAX requests
Author: By
Last change:
Date: 16 years ago
Size: 3,603 bytes
 

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AJAX_Locking is a framework in AJAX to manage locking of object in a web application. The idea is "stolen" from David Perelman-Hall's column appeared in DDJ issue on 8th September 2006 http://www.ddj.com/showArticle.jhtml?articleID=192700218 The idea is to use AJAX to lock, unlock and get status of records/objects, avoiding use of locks on db (or transactions). AJAX_Locking is a class that extends HTML_AJAX_Server and implements itself the features to lock, unlock and get status via a "driver": the default driver (AJAX_Locking_Driver_SharedMemory) uses PEAR's package System_SharedMemory as repository of locks, you can write your own driver to achieve the same purpose, using a db or the filesystem. To use AJAX_Locking you have to write a "server" page like the following, that instantiate the Ajax remote object: server.php <?php require_once ('AJAX_Locking/AJAX_Locking.php'); require_once('AJAX_Locking/Driver/SharedMemory.php'); $driver = new AJAX_Locking_Driver_SharedMemory(10, 'file'); $server = new AJAX_Locking($driver); $server->handleRequest(); ?> and in your client page you have to use HTML_Ajax framework to call lock, unlock and status methods provided from server. AJAX_Locking provides its own javascript library to help to write client-side management: test.php <?php $user='fabamb'; $type='test'; $id =1; ?> <html> <head> <script type = 'text/javascript' src = "server.php?client=Locking,all&stub=all"></script> <script type = "text/javascript"> var lockingCallbacks = { count: 0, lock: function(result) { if (result === true) { h.status(); } else { h.stop(); HTML_AJAX_Util.setInnerHTML('status', 'Errore durante il lock'); } }, unlock: function(result) { if (result === true) { h.status(); } else { h.stop(); HTML_AJAX_Util.setInnerHTML('status', 'Errore durante l\'unlock'); } }, status: function(result) { HTML_AJAX_Util.setInnerHTML('count', this.count++); var values = result.split('~'); switch (values[0]) { case 'owned': html = '<img src=owned.png align=absmiddle>In fase di modifica'; enableButton('editButton', false); enableButton('saveButton', true); break; case 'locked': html = '<img src=locked.png align=absmiddle>Bloccato da ' + values[1]; enableButton('editButton', false); enableButton('saveButton', false); break; case 'unlocked': html = '<img src=unlocked.png align=absmiddle>'; enableButton('editButton', true); enableButton('saveButton', false); break; case 'timeout': h.stop(); html = '<img src=timeout.png align=absmiddle>Fase di modifica scaduta'; enableButton('editButton', false); enableButton('saveButton', false); break; } HTML_AJAX_Util.setInnerHTML('status', html); } } function enableButton(id, enabled) { var button = document.getElementById(id); if (button) button.disabled = !enabled; } var h = new AJAX_Locking_Handler(lockingCallbacks, '<?=$user?>', '<?=$type?>', <?=$id?>); </script> </head> <body onload = 'h.start();'> <div id = "count"> </div> User: <?= $user ?><br> Tipo <?= $type ?><br> Id: <?= $id ?><br> Status: <span id = "status"></span> <br> <button id = "editButton" type = "button" onClick = "h.lock()">Edit</button> <button id = "saveButton" type = "button" onClick = "h.unlock()" disabled>Save</button> <button id = "statusButton" type = "button" onClick = "h.status()">Status</button> <br> </body> </html>