SessionHandler.php

<?php


/**
 * This file is part of SimpleSAMLphp. See the file COPYING in the
 * root of the distribution for licence information.
 *
 * This file defines a base class for session handling.
 * Instantiation of session handler objects should be done through
 * the class method getSessionHandler().
 *
 * @author Olav Morken, UNINETT AS. <andreas.solberg@uninett.no>
 * @package SimpleSAMLphp
 */
abstract class SimpleSAML_SessionHandler
{


    /**
     * This static variable contains a reference to the current
     * instance of the session handler. This variable will be NULL if
     * we haven't instantiated a session handler yet.
     *
     * @var SimpleSAML_SessionHandler
     */
    private static $sessionHandler = null;


    /**
     * This function retrieves the current instance of the session handler.
     * The session handler will be instantiated if this is the first call
     * to this function.
     *
     * @return SimpleSAML_SessionHandler The current session handler.
     */
    public static function getSessionHandler()
    {
        if (self::$sessionHandler === null) {
            self::createSessionHandler();
        }

        return self::$sessionHandler;
    }


    /**
     * This constructor is included in case it is needed in the the
     * future. Including it now allows us to write parent::__construct() in
     * the subclasses of this class.
     */
    protected function __construct()
    {
    }


    /**
     * Create and set new session id.
     *
     * @return string The new session id.
     */
    abstract public function newSessionId();


    /**
     * Retrieve the session ID saved in the session cookie, if there's one.
     *
     * @return string|null The session id saved in the cookie or null if no session cookie was set.
     */
    abstract public function getCookieSessionId();