diff --git a/composer.json b/composer.json
index aafa267..9ae84d0 100644
--- a/composer.json
+++ b/composer.json
@@ -28,12 +28,12 @@
     },
     "autoload": {
         "psr-4": {
-            "mirzaev\\yii2\\arangodb\\sessions\\": "mirzaev/yii2-arangodb-sessions"
+            "mirzaev\\yii2\\arangodb\\sessions\\": "mirzaev/yii2/arangodb/sessions"
         }
     },
     "autoload-dev": {
         "psr-4": {
-            "mirzaev\\yii2\\arangodb\\sessions\\tests\\": "mirzaev/yii2-arangodb-sessions/tests"
+            "mirzaev\\yii2\\arangodb\\sessions\\tests\\": "mirzaev/yii2/arangodb/sessions/tests"
         }
     }
 }
\ No newline at end of file
diff --git a/mirzaev/yii2-arangodb-sessions/ArangoDbSession.php b/mirzaev/yii2-arangodb-sessions/ArangoDbSession.php
deleted file mode 100644
index ff1cc18..0000000
--- a/mirzaev/yii2-arangodb-sessions/ArangoDbSession.php
+++ /dev/null
@@ -1,288 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace mirzaev\yii2\arangodb\sessions;
-
-use yii;
-use yii\web\DbSession;
-use yii\db\PdoValue;
-use yii\di\Instance;
-use yii\base\InvalidConfigException;
-
-use mirzaev\yii2\arangodb\Connection;
-use mirzaev\yii2\arangodb\Query;
-
-use Exception;
-
-/**
- * Реализация DbSession под ArangoDB
- *
- * @package Yii2\ArangoDB
- * @author Arsen Mirzaev Tatyano-Muradovich <red@hood.su>
- */
-final class ArangoDbSession extends DbSession {
-
-    /**
-     * Идентификатор компонента (Component ID)
-     */
-    public Connection|array|string $db = 'arangodb';
-
-    /**
-     * Название документа для хранения данных сеанса (Document name for storing session data)
-     */
-    public string $sessions = 'sessions';
-
-    /**
-     * Буфер данных для записи в документ сессий (Data buffer for write to session document)
-     */
-    protected array $buffer = [];
-
-
-    /**
-     * Инициализация компонента (Component initialization)
-     *
-     * @throws InvalidConfigException if $this->db is invalid.
-     */
-    public function init(): self
-    {
-        parent::init();
-
-        return $this->db = Instance::ensure($this->db, Connection::class);
-    }
-
-    /**
-     * Открыть сессию (Open session)
-     *
-     * @param string $path session save path
-     * @param string $name session name
-     *
-     * @return bool Статус открытия сессии (Session opening status)
-     *
-     * @internal Do not call this method directly
-     */
-    public function openSession($path, $name): bool
-    // public function openSession(string $save, string $session_name): bool
-    {
-        if ($this->getUseStrictMode()) {
-            $id = $this->getId();
-            if (!$this->getReadQuery($id)->exists()) {
-                // This session id does not exist, mark it for forced regeneration
-                $this->_forceRegenerateId = $id;
-            }
-        }
-
-        return parent::openSession($path, $name);
-    }
-
-    /**
-     * Метод не создаст эффект пока сессия неактивна (getIsActive()). Убедитесь, что открыли (open()) перед вызовом
-     * This method has no effect when session is not [[getIsActive()|active]]. Make sure to call [[open()]] before calling it.
-     *
-     * @param bool $delete Удалить прошлую сессию (Delete old session)
-     *
-     * @see $this->open()
-     * @see $this->getIsActive()
-     * @see https://secure.php.net/session_regenerate_id
-     */
-    public function regenerateID($delete = false): void
-    // public function regenerateID(bool $delete = false): void
-    {
-        $oldID = session_id();
-
-        // if no session is started, there is nothing to regenerate
-        if (empty($oldID)) {
-            return;
-        }
-
-        parent::regenerateID(false);
-
-        $newID = session_id();
-
-        // if session id regeneration failed, no need to create/update it.
-        if (empty($newID)) {
-            Yii::warning('Failed to generate new session ID', __METHOD__);
-            return;
-        }
-
-        $row = $this->db->useMaster(function() use ($oldID) {
-            return (new Query())->from($this->sessionTable)
-               ->where(['id' => $oldID])
-               ->createCommand($this->db)
-               ->queryOne();
-        });
-
-        if ($row !== false) {
-            if ($delete) {
-                $this->db->createCommand()
-                    ->update($this->sessionTable, ['id' => $newID], ['id' => $oldID])
-                    ->execute();
-            } else {
-                $row['id'] = $newID;
-                $this->db->createCommand()
-                    ->insert($this->sessionTable, $row)
-                    ->execute();
-            }
-        } else {
-            // shouldn't reach here normally
-            $this->db->createCommand()
-                ->insert($this->sessionTable, $this->composeFields($newID, ''))
-                ->execute();
-        }
-    }
-
-    /**
-     * Закрыть сессию (Close session)
-     *
-     * Закрывает текущую сессию и сохраняет данные
-     * Ends the current session and store session data
-     */
-    public function close(): void
-    {
-        if ($this->getIsActive()) {
-            // prepare writeCallback fields before session closes
-            $this->fields = $this->composeFields();
-            YII_DEBUG ? session_write_close() : @session_write_close();
-        }
-    }
-
-    /**
-     * Прочитать сессию (Read session)
-     *
-     * @param string $id Идентификатор сессии (Session ID)
-     *
-     * @return string Данные сессии (The session data)
-     *
-     * @internal Do not call this method directly
-     */
-    public function readSession($id): string
-    // public function readSession(string $id): string
-    {
-        $query = $this->getReadQuery($id);
-
-        if ($this->readCallback !== null) {
-            $fields = $query->one($this->db);
-            return $fields === false ? '' : $this->extractData($fields);
-        }
-
-        $data = $query->select(['data'])->scalar($this->db);
-        return $data === false ? '' : $data;
-    }
-
-    /**
-     * Записать сессию (Write session)
-     *
-     * @param string $id Идентификатор сессии (Session ID)
-     * @param string $data Данные сессии (Session data)
-     *
-     * @return bool Статус записи сессии (Session writing status)
-     *
-     * @internal Do not call this method directly
-     */
-    public function writeSession($id, $data): bool
-    // public function writeSession(string $id, string $data): bool
-    {
-        if ($this->getUseStrictMode() && $id === $this->_forceRegenerateId) {
-            //Ignore write when forceRegenerate is active for this id
-            return true;
-        }
-
-        // exception must be caught in session write handler
-        // https://secure.php.net/manual/en/function.session-set-save-handler.php#refsect1-function.session-set-save-handler-notes
-        try {
-            // ensure backwards compatability (fixed #9438)
-            if ($this->writeCallback && !$this->fields) {
-                $this->fields = $this->composeFields();
-            }
-            // ensure data consistency
-            if (!isset($this->fields['data'])) {
-                $this->fields['data'] = $data;
-            } else {
-                $_SESSION = $this->fields['data'];
-            }
-            // ensure 'id' and 'expire' are never affected by [[writeCallback]]
-            $this->fields = array_merge($this->fields, [
-                'id' => $id,
-                'expire' => time() + $this->getTimeout(),
-            ]);
-            $this->fields = $this->typecastFields($this->fields);
-            $this->db->createCommand()->upsert($this->sessionTable, $this->fields)->execute();
-            $this->fields = [];
-        } catch (Exception $e) {
-            Yii::$app->errorHandler->handleException($e);
-            return false;
-        }
-
-        return true;
-    }
-
-    /**
-     * Удалить сессию (Delete session)
-     *
-     * @param string $id Идентификатор сессии (Session ID)
-     *
-     * @return bool Статус удаления сессии (Session deleting status)
-     *
-     * @internal Do not call this method directly
-     */
-    public function destroySession($id)
-    {
-        $this->db->createCommand()
-            ->delete($this->sessionTable, ['id' => $id])
-            ->execute();
-
-        return true;
-    }
-
-    /**
-     * Удалить неиспользуемые данные (Delete garbage)
-     *.
-     * @param int $max Периодичность очистки в секундах (Cleaning frequency in seconds)
-     *
-     * @return bool Статус очистки неиспользуемых данных сессии (Session garbage deleting status)
-     *
-     * @internal Do not call this method directly
-     */
-    public function gcSession($max): bool
-    // public function gcSession(int $max): bool
-    {
-        $this->db->createCommand()
-            ->delete($this->sessionTable, '[[expire]]<:expire', [':expire' => time()])
-            ->execute();
-
-        return true;
-    }
-
-    /**
-     * Генерация запроса для чтения сеанса (Generating a query to read a session)
-     *
-     * @param string $id Идентификатор сессии (Session ID)
-     */
-    protected function getReadQuery($id): Query
-    // protected function getReadQuery(string $id): Query
-    {
-        return (new Query())
-            ->from($this->sessionTable)
-            ->where('[[expire]]>:expire AND [[id]]=:id', [':expire' => time(), ':id' => $id]);
-    }
-
-    /**
-     * Конвертация для отправки в PDO (Convertation  for sending to PDO)
-     *
-     * Default implementation casts field `data` to `\PDO::PARAM_LOB`.
-     * You can override this method in case you need special type casting.
-     *
-     * @param array $data Данные для конвертации (Data for convertation) [name => value]
-     */
-    protected function typecastFields($data): array
-    // protected function typecastFields(array $data): array
-    {
-        // if (isset($data['data']) && !is_array($data['data']) && !is_object($data['data'])) {
-        //     $data['data'] = new PdoValue($data['data'], \PDO::PARAM_LOB);
-        // }
-
-        // return $data;
-
-        return [];
-    }
-}
\ No newline at end of file
diff --git a/mirzaev/yii2/arangodb/sessions/ArangoDbSession.php b/mirzaev/yii2/arangodb/sessions/ArangoDbSession.php
new file mode 100644
index 0000000..ffeec20
--- /dev/null
+++ b/mirzaev/yii2/arangodb/sessions/ArangoDbSession.php
@@ -0,0 +1,381 @@
+<?php
+
+declare(strict_types=1);
+
+namespace mirzaev\yii2\arangodb\sessions;
+
+use yii;
+use yii\di\Instance;
+use yii\base\InvalidConfigException;
+
+use mirzaev\yii2\arangodb\Connection;
+use mirzaev\yii2\arangodb\Query;
+
+use Exception;
+
+/**
+ * Реализация DbSession под ArangoDB
+ *
+ * @property Connection|array|string $database Идентификатор компонента (Component ID)
+ * @property string $document Название документа для хранения данных сеанса (Document name for storing session data)
+ * @property array $buffer Буфер данных для записи в документ сессии (Data buffer for write to session document)
+ *
+ * @method public init() Инициализация компонента (Component initialization)
+ * @method public openSession() Открыть сессию (Open session)
+ * @method public close() Закрыть сессию (Close session)
+ * @method public regenerateID() Обновление сессии (Update session)
+ * @method public readSession() Прочитать сессию (Read session)
+ * @method public searchSession() Найти сессию (Search session)
+ * @method public initSession() Инициализировать сессию (Initialize session)
+ * @method public writeSession() Записать сессию (Write session)
+ * @method public destroySession() Удалить сессию (Delete session)
+ * @method public gcSession() Удалить неиспользуемые данные (Delete garbage)
+ * @method protected getReadQuery() Генерация запроса для чтения сеанса (Generating a query to read a session)
+ * @method protected typecastFields() Конвертация для отправки в PDO (Convertation  for sending to PDO)
+ *
+ * @example ./Migrations/create_sessions_collection.php
+ *
+ * @uses $this->gcSession() Do not call this method directly
+ * @uses $this->openSession() Do not call this method directly
+ * @uses $this->readSession() Do not call this method directly
+ * @uses $this->writeSession() Do not call this method directly
+ * @uses $this->destroySession() Do not call this method directly
+ *
+ * @see yii\web\DbSession Наследует, копирует (Inherit, copy)
+ *
+ * @package yii2\ArangoDB
+ * @author Arsen Mirzaev Tatyano-Muradovich <red@hood.su>
+ */
+final class ArangoDbSession extends MultiFieldSession
+{
+
+    /**
+     * Идентификатор компонента (Component ID)
+     */
+    public Connection|array|string $database = 'arangodb';
+
+    /**
+     * Название документа для хранения данных сеанса (Document name for storing session data)
+     */
+    public string $document = 'sessions';
+
+    /**
+     * Буфер данных для записи в документ сессии (Data buffer for write to session document)
+     */
+    protected array $buffer = [];
+
+
+    /**
+     * Инициализация компонента (Component initialization)
+     *
+     * @throws InvalidConfigException if $this->database is invalid.
+     */
+    public function init(): Connection
+    {
+        return $this->database = Instance::ensure($this->database, Connection::class);
+    }
+
+    /**
+     * Открыть сессию (Open session)
+     *
+     * @param string $path Путь для сохранения сессии (Path to save session)
+     * @param string $name Имя сессии (Session name)
+     *
+     * @return bool Статус открытия сессии (Session opening status)
+     */
+    public function openSession($path, $name): bool
+    // public function openSession(string $path, string $name): bool
+    {
+        if ($this->getUseStrictMode()) {
+
+            $id = $this->getId();
+
+            if (!$this->getReadQuery($id)->exists()) {
+                // This session id does not exist, mark it for forced regeneration
+                $this->_forceRegenerateId = $id;
+            }
+        }
+
+        return parent::openSession($path, $name);
+    }
+
+    /**
+     * Закрыть сессию (Close session)
+     *
+     * Закрывает текущую сессию и сохраняет данные
+     * Ends the current session and store session data
+     */
+    public function close(): void
+    {
+        if ($this->getIsActive()) {
+            // prepare writeCallback fields before session closes
+
+            $this->buffer = $this->composeFields();
+
+            YII_DEBUG ? session_write_close() : @session_write_close();
+        }
+    }
+
+    /**
+     * Обновление сессии (Update session)
+     *
+     * Метод не создаст эффект пока сессия неактивна (getIsActive()). Убедитесь, что открыли (open()) перед вызовом
+     * This method has no effect when session is not [[getIsActive()|active]]. Make sure to call [[open()]] before calling it.
+     *
+     * @param bool $rewrite Перезаписать прошлую сессию (Rewrite old session)
+     *
+     * @see $this->open()
+     * @see $this->getIsActive()
+     *
+     * @tutorial https://secure.php.net/session_regenerate_id
+     */
+    public function regenerateID($rewrite = false): void
+    // public function regenerateID(bool $rewrite = false): void
+    {
+        // Инициализация
+        $oldID = session_id();
+
+        if (empty($oldID)) {
+            // if no session is started, there is nothing to regenerate
+
+            return;
+        }
+
+        // parent::regenerateID(false);
+
+        $newID = session_id();
+
+        // if session id regeneration failed, no need to create/update it.
+        if (empty($newID)) {
+            yii::warning('Failed to generate new session ID', __METHOD__);
+
+            return;
+        }
+
+        $row = (new Query())
+                ->in($this->document)
+                ->where(['hash' => $oldID])
+                ->one($this->database);
+
+        if ($row) {
+            if ($rewrite) {
+                // Обновить
+
+                (new Query())
+                    ->in($this->document)
+                    ->where(['hash' => $newID])
+                    ->update(['hash' => $oldID], db: $this->database);
+            } else {
+                // Создать
+
+                (new Query())
+                    ->in($this->document)
+                    ->insert(['hash' => $newID], db: $this->database);
+            }
+        } else {
+            // shouldn't reach here normally
+            (new Query())
+                ->in($this->document)
+                ->insert($this->composeFields($newID, ''), db: $this->database);
+        }
+    }
+
+    /**
+     * Прочитать сессию (Read session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     *
+     * @return string Данные сессии (The session data)
+     */
+    public function readSession($id): string
+    // public function readSession(string $id): string
+    {
+        $query = $this->getReadQuery($id);
+
+
+        if ($this->readCallback !== null) {
+            $data = $query->one($this->database);
+
+            return $data ? $this->extractData($data) : '';
+        }
+
+        $data = $query->select(['data' => 'data'])->one($this->database);
+
+        return $data['data'] ?? '';
+    }
+
+    /**
+     * Найти сессию (Search session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     *
+     * @return array|null Сессия, если найдена (Session, if founded)
+     */
+    public function searchSession(string $id): ?array
+    {
+        $session = (new Query())
+            ->in($this->document)
+            ->where(['hash' => $id])
+            ->one($this->database);
+
+        return $session ? $session : null;
+    }
+
+    /**
+     * Инициализировать сессию (Initialize session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     *
+     * @return array Сессия (Session)
+     */
+    public function initSession(string $id): array
+    {
+        return $this->searchSession($id) ?? (new Query())
+            ->in($this->document)
+            ->insert($this->buffer, db: $this->database);
+    }
+
+    /**
+     * Записать сессию (Write session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     * @param string $data Данные сессии (Session data)
+     *
+     * @return bool Статус записи сессии (Session writing status)
+     */
+    public function writeSession($id, $data): bool
+    // public function writeSession(string $id, string $data): bool
+    {
+        if ($this->getUseStrictMode() && $id === $this->_forceRegenerateId) {
+            //Ignore write when forceRegenerate is active for this id
+            return true;
+        }
+
+        // exception must be caught in session write handler
+        // https://secure.php.net/manual/en/function.session-set-save-handler.php#refsect1-function.session-set-save-handler-notes
+        try {
+            // ensure backwards compatability (fixed #9438)
+            if ($this->writeCallback && !$this->buffer) {
+                $this->buffer = $this->composeFields();
+            }
+
+            // ensure data consistency
+            if (isset($this->buffer['data'])) {
+                $_SESSION = $this->buffer['data'];
+            } else {
+                $this->buffer['data'] = $data;
+            }
+
+            $this->buffer = array_merge($this->buffer, [
+                'hash' => $id,
+                'from' => time(),
+                'to' => time() + $this->getTimeout(),
+            ]);
+
+            // Конвертация или сериализация, не пойму
+            $this->buffer = $this->typecastFields($this->buffer);
+
+            // Инициализация сессии
+            $this->initSession($id);
+
+            // Деинициализация буфера данных сессии
+            $this->buffer = [];
+        } catch (Exception $e) {
+            yii::$app->errorHandler->handleException($e);
+
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Удалить сессию (Delete session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     *
+     * @return bool Статус удаления сессии (Session deleting status)
+     */
+    public function destroySession($id): bool
+    // public function destroySession(string $id): bool
+    {
+        return (new Query())
+            ->in($this->document)
+            ->where([
+                'hash' => $id
+            ])
+            ->remove(db: $this->database);
+    }
+
+    /**
+     * Удалить неиспользуемые данные (Delete garbage)
+     *
+     * Очищает от сессий чей срок хранения истёк
+     * Clears sessions whose retention period has expired
+     *.
+     * @param int $max Периодичность очистки в секундах (Cleaning frequency in seconds)
+     *
+     * @return bool Статус удаления устаревших сессий (Deletion status of obsolete sessions)
+     */
+    public function gcSession($max): bool
+    // public function gcSession(int $max): bool
+    {
+        return (new Query())
+            ->in($this->document)
+            ->where([
+                [
+                    [
+                        'to' => time()
+                    ],
+                    'operator' => '>='
+                ]
+            ])
+            ->remove(db: $this->database);
+    }
+
+    /**
+     * Генерация запроса для чтения сеанса (Generating a query to read a session)
+     *
+     * @param string $id Идентификатор сессии (Session ID)
+     *
+     * @return Query Инстанция запроса на чтение (Read query instance)
+     */
+    protected function getReadQuery(string $id): Query
+    {
+        return (new Query())
+            ->in($this->document)
+            ->where([
+                [
+                    [
+                        'to' => time()
+                    ],
+                    'operator' => '<='
+                ]
+            ])
+            ->where([
+                [
+                    'to' => null
+                ]
+            ], 'OR')
+            ->where([
+                [
+                    'hash' => $id,
+                ],
+            ]);
+    }
+
+    /**
+     * Конвертация для отправки в PDO (Convertation  for sending to PDO)
+     *
+     * Default implementation casts field `data` to `\PDO::PARAM_LOB`.
+     * You can override this method in case you need special type casting.
+     *
+     * @param array $data Данные для конвертации (Data for convertation) [name => value]
+     *
+     * @return array Конвертированные данные (Converted data)
+     */
+    protected function typecastFields(array $data): array
+    {
+        return $data;
+    }
+}
diff --git a/mirzaev/yii2/arangodb/sessions/Migrations/create_sessions_collection.php b/mirzaev/yii2/arangodb/sessions/Migrations/create_sessions_collection.php
new file mode 100644
index 0000000..67fac6e
--- /dev/null
+++ b/mirzaev/yii2/arangodb/sessions/Migrations/create_sessions_collection.php
@@ -0,0 +1,20 @@
+<?php
+
+use mirzaev\yii2\arangodb\Migration;
+
+class create_sessions_collection extends Migration
+{
+    public function up()
+    {
+        /**
+         * @param string Название коллекции
+         * @param array Тип коллекции (2 - документ, 3 - ребро)
+         */
+        $this->createCollection('sessions', ['type' => 2]);
+    }
+
+    public function down()
+    {
+        $this->dropCollection('sessions');
+    }
+}
\ No newline at end of file
diff --git a/mirzaev/yii2/arangodb/sessions/MultiFieldSession.php b/mirzaev/yii2/arangodb/sessions/MultiFieldSession.php
new file mode 100644
index 0000000..4c60528
--- /dev/null
+++ b/mirzaev/yii2/arangodb/sessions/MultiFieldSession.php
@@ -0,0 +1,134 @@
+<?php
+
+declare(strict_types=1);
+
+namespace mirzaev\yii2\arangodb\sessions;
+
+use yii;
+
+use yii\web\Session;
+
+/**
+ * Базовый класс для реализации хранилища сессий
+ *
+ * MultiFieldSession is the base class for session storage implementations with multi-field data storage support
+ *
+ * @property-read bool $useCustomStorage Разрешение использовать своё хранилища (Whether to use custom storage)
+ *
+ * @author Arsen Mirzaev Tatyano-Muradovich <red@hood.su>
+ * @author Paul Klimov <klimov.paul@gmail.com>
+ */
+abstract class MultiFieldSession extends Session
+{
+    /**
+     * @var callable a callback that will be called during session data reading.
+     * The signature of the callback should be as follows:
+     *
+     * ```
+     * function ($fields)
+     * ```
+     *
+     * where `$fields` is the storage field set for read session and `$session` is this session instance.
+     * If callback returns an array, it will be merged into the session data.
+     *
+     * Example:
+     *
+     * ```php
+     * function ($fields) {
+     *     return [
+     *         'expireDate' => Yii::$app->formatter->asDate($fields['expire']),
+     *     ];
+     * }
+     * ```
+     */
+    public $readCallback;
+
+    /**
+     * @var callable a callback that will be called during session data writing.
+     * The signature of the callback should be as follows:
+     *
+     * ```
+     * function ($session)
+     * ```
+     *
+     * where `$session` is this session instance, this variable can be used to retrieve session data.
+     * Callback should return the actual fields set, which should be saved into the session storage.
+     *
+     * For example:
+     *
+     * ```php
+     * function ($session) {
+     *     return [
+     *         'user_id' => Yii::$app->user->id,
+     *         'ip' => $_SERVER['REMOTE_ADDR'],
+     *         'is_trusted' => $session->get('is_trusted', false),
+     *     ];
+     * }
+     * ```
+     */
+    public $writeCallback;
+
+    /**
+     * Returns a value indicating whether to use custom session storage.
+     * This method overrides the parent implementation and always returns true.
+     *
+     * @return bool whether to use custom storage.
+     */
+    public function getUseCustomStorage(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Composes storage field set for session writing.
+     *
+     * @param string $id Optional session id
+     * @param string $data Optional session data
+     *
+     * @return array storage fields
+     */
+    protected function composeFields($id = null, $data = null): array
+    {
+        $buffer = $this->writeCallback ? call_user_func($this->writeCallback, $this) : [];
+
+        if ($id !== null) {
+            $buffer['hash'] = $id;
+        }
+
+        if ($data !== null) {
+            $buffer['data'] = $data;
+        }
+
+        return $buffer;
+    }
+
+    /**
+     * Extracts session data from storage field set.
+     *
+     * @param array $buffer storage buffer.
+     *
+     * @return string session data.
+     */
+    protected function extractData(array $buffer): string
+    {
+        if ($this->readCallback !== null) {
+            if (!isset($buffer['data'])) {
+                $buffer['data'] = '';
+            }
+
+            $extraData = call_user_func($this->readCallback, $buffer);
+
+            if (!empty($extraData)) {
+                session_decode($buffer['data']);
+
+                $_SESSION = array_merge((array) $_SESSION, (array) $extraData);
+
+                return session_encode();
+            }
+
+            return $buffer['data'];
+        }
+
+        return isset($buffer['data']) ? $buffer['data'] : '';
+    }
+}