Abstract-Requirements engineering (RE) involves processing informal natural language descriptions of system requirements into an integrated and structured formal specification. The traditional RE process is ad-hoc, laborious, time-consuming, and error-prone manual process. For large-scale software intensive systems, the RE process becomes very difficult to manage. It is further complicated by ill-defined, incomplete, and redundantly specified requirements. To streamline the process, an end-to-end seamless RE framework is therefore needed. In this paper, we present an overview of an end-to-end semi-automated changetolerant interactive requirements engineering (iRE) framework. It keeps and maintains the meta-level information of the interrelated requirements models into a semantic network model (SNM), and provides a method and processing system to derive an integrated and structured model. The iRE involves the requirements analysts in an interactive fashion during the modeling process. Index Terms-Requirements Engineering, Behavior Engineering, Behavior Trees, Semantic Network Model, Defects Detection, Change Management, Model Integration.