The SessionHandlerInterface class

(PHP 5 >= 5.4.0)

Introduction

SessionHandlerInterface is an interface which defines a prototype for creating a custom session handler. In order to pass a custom session handler to session_set_save_handler() using its OOP invocation, the class must implement this interface.

Please note the callback methods of this class are designed to be called internally by PHP and are not meant to be called from user-space code.

Class synopsis

SessionHandlerInterface {
/* Methods */
abstract public bool close ( void )
abstract public bool destroy ( string $session_id )
abstract public bool gc ( string $maxlifetime )
abstract public bool open ( string $save_path , string $session_id )
abstract public string read ( string $session_id )
abstract public bool write ( string $session_id , string $session_data )
}

Example #1 Example using SessionHandlerInterface

The following example provides file based session storage similar to the PHP sessions default save handler files. This example could easily be extended to cover database storage using your favorite PHP supported database engine.

Note we use the OOP prototype with session_set_save_handler() and register the shutdown function using the function's parameter flag. This is generally advised when registering objects as session save handlers.

<?php
class MySessionHandler implements SessionHandlerInterface
{
    private $savePath;

    public function open($savePath, $sessionName)
    {
        $this->savePath = $savePath;
        if (!is_dir($this->savePath)) {
            mkdir($this->savePath, 0777);
        }

        return true;
    }

    public function close()
    {
        return true;
    }

    public function read($id)
    {
        return (string)@file_get_contents("$this->savePath/sess_$id");
    }

    public function write($id, $data)
    {
        return file_put_contents("$this->savePath/sess_$id", $data) === false ? false : true;
    }

    public function destroy($id)
    {
        $file = "$this->savePath/sess_$id";
        if (file_exists($file)) {
            unlink($file);
        }

        return true;
    }

    public function gc($maxlifetime)
    {
        foreach (glob("$this->savePath/sess_*") as $file) {
            if (filemtime($file) + $maxlifetime < time() && file_exists($file)) {
                unlink($file);
            }
        }

        return true;
    }
}

$handler = new MySessionHandler();
session_set_save_handler($handler, true);
session_start();

// proceed to set and retrieve values by key from $_SESSION

Table of Contents