  Wireless Sensor Networks (WSNs) have become very popular and are being used
in many application domains (e.g. smart cities, security, gaming and
agriculture). Virtualized WSNs allow the same WSN to be shared by multiple
applications. Semantic applications are situation-aware and can potentially
play a critical role in virtualized WSNs. However, provisioning them in such
settings remains a challenge. The key reason is that semantic applications
provisioning mandates data annotation. Unfortunately it is no easy task to
annotate data collected in virtualized WSNs. This paper proposes a data
annotation architecture for semantic applications in virtualized heterogeneous
WSNs. The architecture uses overlays as the cornerstone, and we have built a
prototype in the cloud environment using Google App Engine. The early
performance measurements are also presented.
