Software Defined Networks (SDN) are becoming a cornerstone in future network architectures. In this regard, building a global network view upon heterogeneous multiple SDN controllers is a challenging task. In fact, each controller exposes its local network view using different conceptual model. To address this problem, we propose a semantic-based framework that encompasses an approach to extract a local ontology from each controller. The framework incorporates algorithms that map the ontologies together and form the overall network view. We apply our framework in two scenarios: a centralized scenario where the SDN controllers expose their network views to a centralized entity (e.g. management application) that builds the network view, and a distributed scenario, where SDN controllers exchange in peer to peer their local network views and build locally the global view. We present also an evaluation of our framework with respect to performance and accuracy and discuss future works