...

net/adc_net_concepts.h

@@ -47,7 +47,7 @@ using adc_common_duration_t = adc_duration_common_type_t<std::chrono::nanosecond
                                                          std::chrono::months,
                                                          std::chrono::years>;
 
-// concepts for asynchronous opereration callback callable first argument type (asynchronous operation error)
+// concepts for asynchronous operation callback callable first argument type (asynchronous operation error)
 //      1) the type must be convertible to boolean and
 //         a) true - asynchronous operation completed without errors
 //         b) false - an error occured
@@ -106,6 +106,9 @@ concept adc_netservice_c = requires(SRVT srv, const SRVT srv_const) {
     typename SRVT::endpoint_t;  // a type representing endpoint of the network service
                                 // underlying protocol
 
+    // asynchronous operation error
+    requires adc_async_callback_err_t<typename SRVT::async_callback_err_t>;
+
     // callback callables for asynchronous operations
     requires adc_async_callback_t<typename SRVT::async_connect_callback_t>;
     requires adc_async_callback_t<typename SRVT::async_send_callback_t>;