- 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, std::unique_ptr<resource::SplitDuplexLinkImpl>, std::less<>> split_duplex_links_;