diff --git a/src/module-elasticsuite-virtual-category/Api/Data/VirtualRuleInterface.php b/src/module-elasticsuite-virtual-category/Api/Data/VirtualRuleInterface.php
new file mode 100644
index 000000000..ef28804b0
--- /dev/null
+++ b/src/module-elasticsuite-virtual-category/Api/Data/VirtualRuleInterface.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * DISCLAIMER
+ * Do not edit or add to this file if you wish to upgrade Smile Elastic Suite to newer
+ * versions in the future.
+ *
+ * @category  Smile
+ * @package   Smile\ElasticsuiteVirtualCategory
+ * @author    Romain Ruaud <romain.ruaud@smile.fr>
+ * @copyright 2016 Smile
+ * @license   Open Software License ("OSL") v. 3.0
+ */
+namespace Smile\ElasticsuiteVirtualCategory\Api\Data;
+
+use Magento\Catalog\Api\Data\CategoryInterface;
+
+/**
+ * Virtual Category Rule Interface.
+ *
+ * @category Smile
+ * @package  Smile\ElasticsuiteVirtualCategory
+ * @author   Romain Ruaud <romain.ruaud@smile.fr>
+ */
+interface VirtualRuleInterface
+{
+    /**
+     * Build search query by category.
+     *
+     * @param CategoryInterface $category           Search category.
+     * @param array             $excludedCategories Categories that should not be used into search query building.
+     *                                              Used to avoid infinite recursion while building virtual categories rules.
+     *
+     * @return \Smile\ElasticsuiteCore\Search\Request\QueryInterface
+     */
+    public function getCategorySearchQuery($category, $excludedCategories = []);
+
+    /**
+     * Retrieve search queries of children categories.
+     *
+     * @param CategoryInterface $rootCategory Root category.
+     *
+     * @return \Smile\ElasticsuiteCore\Search\Request\QueryInterface[]
+     */
+    public function getSearchQueriesByChildren(CategoryInterface $rootCategory);
+}
diff --git a/src/module-elasticsuite-virtual-category/Model/Rule.php b/src/module-elasticsuite-virtual-category/Model/Rule.php
index 91ffb4582..5eb99d447 100644
--- a/src/module-elasticsuite-virtual-category/Model/Rule.php
+++ b/src/module-elasticsuite-virtual-category/Model/Rule.php
@@ -16,6 +16,7 @@
 
 use Smile\ElasticsuiteCore\Search\Request\QueryInterface;
 use Magento\Catalog\Api\Data\CategoryInterface;
+use Smile\ElasticsuiteVirtualCategory\Api\Data\VirtualRuleInterface;
 
 /**
  * Virtual category rule.
@@ -26,7 +27,7 @@
  * @package  Smile\ElasticsuiteVirtualCategory
  * @author   Aurelien FOUCRET <aurelien.foucret@smile.fr>
  */
-class Rule extends \Smile\ElasticsuiteCatalogRule\Model\Rule
+class Rule extends \Smile\ElasticsuiteCatalogRule\Model\Rule implements VirtualRuleInterface
 {
     /**
      * @var \Smile\ElasticsuiteCore\Search\Request\Query\QueryFactory
diff --git a/src/module-elasticsuite-virtual-category/etc/extension_attributes.xml b/src/module-elasticsuite-virtual-category/etc/extension_attributes.xml
new file mode 100644
index 000000000..426a838da
--- /dev/null
+++ b/src/module-elasticsuite-virtual-category/etc/extension_attributes.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<!--
+/**
+ * Smile_ElasticsuiteVirtualCategory Extension Attributes Configuration.
+ *
+ * DISCLAIMER
+ *
+ * Do not edit or add to this file if you wish to upgrade Smile Elastic Suite to newer
+ * versions in the future.
+ *
+ *
+ * @category  Smile
+ * @package   Smile\ElasticsuiteVirtualCategory
+ * @author    Romain Ruaud <romain.ruaud@smile.fr>
+ * @copyright 2016 Smile
+ * @license   Open Software License ("OSL") v. 3.0
+ */
+ -->
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
+    <extension_attributes for="Magento\Catalog\Api\Data\CategoryInterface">
+        <attribute code="virtual_rule" type="Smile\ElasticsuiteVirtualCategory\Api\Data\VirtualRuleInterface" />
+    </extension_attributes>
+</config>