std::map<std::string, resource::LinkImpl*, std::less<>> links_;
/* save split-duplex links separately, keep links_ with only LinkImpl* seen by the user
* members of a split-duplex are saved in the links_ */
std::map<std::string, resource::LinkImpl*, std::less<>> links_;
/* save split-duplex links separately, keep links_ with only LinkImpl* seen by the user
* members of a split-duplex are saved in the links_ */