The Internet of Things (IoT) vision is being realised recently with many advances in computation and communication technologies and an increasing number of devices with Internet connectivity. Recent efforts have been made to leverage data from these connected devices to deliver value added services and applications. They are usually limited to either data acquisition and management tasks, or programming a closely related group of devices (e.g have the same owner or from the same vendor). This turns the IoT vision into just a straightforward extension of Wireless Sensor Networks (WSNs) where sensors are connected to the Internet. In contrast, from our point of view the IoT distinguishes itself by facilitating interactions between devices from different owners and vendors that deliver services and applications to end-users. In this work, we explore the problem of how to enable the development of IoT applications that exploit large numbers of connected things, belonging to different owners, in an efficient manner.