Internet of Thing (IoT) is transforming our physical world into a giant information system, daily providing novel, advanced, cyberphysical services. Differently from conventional computing services (e.g., web-services, and ubiquitous services) that are usually loosely impacted by contextawareness,
co-location or transience, Internet of Things (IoT) services require to actually consider the overall spatio-temporal context of the heterogeneous entities involved in the service
provisioning. This paper proposes a novel and full-fledged approach to IoT service modeling, aiming to fully support IoT service development according to opportunistic properties.