diff --git a/lang/en/payment.php b/lang/en/payment.php
index 9d0e615ab69..632f3be2769 100644
--- a/lang/en/payment.php
+++ b/lang/en/payment.php
@@ -22,6 +22,7 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+$string['callbacknotimplemented'] = 'The callback is not implemented for component {$a}.';
 $string['nogateway'] = 'There is no payment gateway that can be used.';
 $string['nogatewayselected'] = 'You first need to select a payment gateway.';
 $string['selectpaymenttype'] = 'Select payment type';
diff --git a/payment/classes/helper.php b/payment/classes/helper.php
index 6c4d631e6d8..0c8687567d8 100644
--- a/payment/classes/helper.php
+++ b/payment/classes/helper.php
@@ -113,4 +113,40 @@ class helper {
             'data-description' => $description,
         ];
     }
+
+    /**
+     * Asks the cost from the related component.
+     *
+     * @param string $component Name of the component that the componentid belongs to
+     * @param int $componentid An internal identifier that is used by the component
+     * @return array['amount' => float, 'currency' => string]
+     * @throws \moodle_exception
+     */
+    public static function get_cost(string $component, int $componentid): array {
+        $cost = component_class_callback("$component\\payment\\provider", 'get_cost', [$componentid]);
+
+        if ($cost === null) {
+            throw new \moodle_exception('callbacknotimplemented', 'core_payment', '', $component);
+        }
+
+        return $cost;
+    }
+
+    /**
+     * Delivers what the user paid for.
+     *
+     * @param string $component Name of the component that the componentid belongs to
+     * @param int $componentid An internal identifier that is used by the component
+     * @return bool Whether successful or not
+     * @throws \moodle_exception
+     */
+    public static function deliver_order(string $component, int $componentid): bool {
+        $result = component_class_callback("$component\\payment\\provider", 'deliver_order', [$componentid]);
+
+        if ($result === null) {
+            throw new \moodle_exception('callbacknotimplemented', 'core_payment', '', $component);
+        }
+
+        return $result;
+    }
 }
diff --git a/payment/classes/local/callback/provider.php b/payment/classes/local/callback/provider.php
new file mode 100644
index 00000000000..5d9db19eaab
--- /dev/null
+++ b/payment/classes/local/callback/provider.php
@@ -0,0 +1,50 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * This file contains the \core_payment\local\local\callback\provider interface.
+ *
+ * Plugins should implement this if they use payment subsystem.
+ *
+ * @package core_payment
+ * @copyright 2020 Shamim Rezaie <shamim@moodle.com>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core_payment\local\callback;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The provider interface for plugins to provide callbacks which are needed by the payment subsystem.
+ *
+ * @copyright  2020 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+interface provider {
+
+    /**
+     * @param int $identifier An identifier that is known to the plugin
+     * @return array['amount' => float, 'currency' => string]
+     */
+    public static function get_cost(int $identifier): array;
+
+    /**
+     * @param int $identifier An identifier that is known to the plugin
+     * @return bool Whether successful or not
+     */
+    public static function deliver_order(int $identifier): bool;
+}