typedef struct a_server_context {
   void ( SQL_CALLBACK *set_error )(
                                   a_server_context *This
                                   , a_sql_uint32 error_code
                                   , const char* error_string
                                   , short str_len );
   void ( SQL_CALLBACK *log_message )(
                                   a_server_context *This
                                   , const char* message
                                   , short msg_len );
   a_sql_uint32 ( SQL_CALLBACK *get_is_cancelled )(
                                   a_server_context *This );
   void      *_context;
} a_server_context;