Abstract
The digital content in smart city, is a critical asset. It can be used for multiple purposes and offers added value layers for customization and personalization of services. Numerous research issues, related to standardization, annotation, visualization and sentiment analysis pose critical research questions. In our approach within a greatest context of academic research we deal with the semi-automatic annotation of smart city contexts, and more specifically the annotation of twitter-content for the promotion of citizen's engagement. We discuss in detail the feasibility of technical approaches with the deployment of open platforms and approaches, towards value adding services. The greatest challenge of our research is to promote an open-collaborative semantic annotation framework for social content in smart city, promoting engagement modes.