Lightweight, dynamic mechanisms are provided to support service layer interworking and resource extensibility. For example, one mechanism disclosed herein comprises defining a new service layer (SL) resource definition registration procedure that allows for specifying custom attributes of service layer resources to represent third party technology resources. A second mechanism disclosed herein comprises defining a new SL data model mapping registration procedure to map service layer resources to third party data models and to provide a new interworked retargeting indicator to the service layer. Further, a third mechanism disclosed herein comprises defining a SL generic interworking procedure to intelligently retarget requests toward interworked resources based on the interworked retargeting indicator provided by the data model mapping.