+XBT_PUBLIC_DATA( surf_callback(void, NetworkLinkPtr)) networkLinkDestructedCallbacks;
+
+/** @ingroup SURF_callbacks
+ * @brief Callbacks handler which emits the callbacks after NetworkLink State changed
+ * @details Callback functions have the following signature: `void(NetworkLinkActionPtr action, e_surf_resource_state_t old, e_surf_resource_state_t current)`
+ */
+XBT_PUBLIC_DATA( surf_callback(void, NetworkLinkPtr, e_surf_resource_state_t, e_surf_resource_state_t)) networkLinkStateChangedCallbacks;