From 9ddbc114a7e6fb4a118c363712842d95c2e84e07 Mon Sep 17 00:00:00 2001
From: Tim van Dijen <tvdijen@gmail.com>
Date: Wed, 5 Aug 2026 10:31:36 +0200
Subject: [PATCH 1/3] Import schema

---
 resources/schemas/saml-async-slo-v1.0.xsd | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 resources/schemas/saml-async-slo-v1.0.xsd

diff --git a/resources/schemas/saml-async-slo-v1.0.xsd b/resources/schemas/saml-async-slo-v1.0.xsd
new file mode 100644
index 000000000..2a64b8917
--- /dev/null
+++ b/resources/schemas/saml-async-slo-v1.0.xsd
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<schema xmlns:aslo="urn:oasis:names:tc:SAML:2.0:protocol:ext:async-slo" 
+        xmlns="http://www.w3.org/2001/XMLSchema"  
+        targetNamespace="urn:oasis:names:tc:SAML:2.0:protocol:ext:async-slo"
+        elementFormDefault="qualified">
+    
+    <element name="Asynchronous" type="aslo:AsynchronousType" />
+    <complexType name="AsynchronousType" />
+
+    <attribute name="supportsAsynchronous" type="boolean"/>
+    
+</schema>

From 12d253ac4355456348c903c0898b983368696bd2 Mon Sep 17 00:00:00 2001
From: Tim van Dijen <tvdijen@gmail.com>
Date: Wed, 5 Aug 2026 10:49:23 +0200
Subject: [PATCH 2/3] Update class-registry

---
 classes/element.registry.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/classes/element.registry.php b/classes/element.registry.php
index 04b8d47de..c33e56524 100644
--- a/classes/element.registry.php
+++ b/classes/element.registry.php
@@ -3,6 +3,9 @@
 declare(strict_types=1);
 
 return [
+    'urn:oasis:names:tc:SAML:2.0:protocol:ext:async-slo' => [
+        'Asynchronous' => '\SimpleSAML\SAML2\XML\aslo\Asynchronous',
+    ],
     'urn:oasis:names:tc:SAML:metadata:algsupport' => [
         'DigestMethod' => '\SimpleSAML\SAML2\XML\alg\DigestMethod',
         'SigningMethod' => '\SimpleSAML\SAML2\XML\alg\SigningMethod',

From 0939f407427bc1a13bb09e80867d4b9ad2cad01b Mon Sep 17 00:00:00 2001
From: Tim van Dijen <tvdijen@gmail.com>
Date: Wed, 5 Aug 2026 10:51:51 +0200
Subject: [PATCH 3/3] Add abstract and NS-constant

---
 src/Constants.php                    |  5 +++++
 src/XML/aslo/AbstractAlsoElement.php | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 src/XML/aslo/AbstractAlsoElement.php

diff --git a/src/Constants.php b/src/Constants.php
index 968fd7817..ac884ff07 100644
--- a/src/Constants.php
+++ b/src/Constants.php
@@ -226,6 +226,11 @@ class Constants extends \SimpleSAML\XMLSecurity\Constants
      */
     public const string NS_ALG = 'urn:oasis:names:tc:SAML:metadata:algsupport';
 
+    /**
+     * The namespace for the SAML 2 Asynchronous Single Logout Profile Extension
+     */
+    public const string NS_ASLO = 'urn:oasis:names:tc:SAML:2.0:protocol:ext:async-slo';
+
     /**
      * The namespace for the ECP protocol.
      */
diff --git a/src/XML/aslo/AbstractAlsoElement.php b/src/XML/aslo/AbstractAlsoElement.php
new file mode 100644
index 000000000..054ae8f14
--- /dev/null
+++ b/src/XML/aslo/AbstractAlsoElement.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML2\XML\aslo;
+
+use SimpleSAML\SAML2\Constants as C;
+use SimpleSAML\XML\AbstractElement;
+
+/**
+ * Abstract class to be implemented by all the classes in this namespace
+ *
+ * @see https://docs.oasis-open.org/security/saml/Post2.0/saml-async-slo/v1.0/saml-async-slo-v1.0.pdf
+ * @package simplesamlphp/saml2
+ */
+abstract class AbstractAlgElement extends AbstractElement
+{
+    public const string NS = C::NS_ASLO;
+
+    public const string NS_PREFIX = 'aslo';
+
+    public const string SCHEMA = 'resources/schemas/saml-async-slo-v1.0.xsd';
+}