Research in Internet-of-Things infrastructures hasso far mainly been focused on connecting sensors and actuatorsto the Internet, while associating these devices to applicationsvia web services. This has contributed to making the technologyaccessible in areas such as smart-grid, transport, health, etc.These early successes have hidden the lack of support forsensor-based applications to share information and limitationsin support for applications to access sensors and actuatorsglobally. We address these limitations in an novel open-sourceplatform, MediaSense. MediaSense offers scalable, seamless,real-time access to global sensors and actuators via hetero-geneous network infrastructure. This paper presents a setof requirements for Internet-of-Things applications support,an overview of our architecture, and application prototypescreated in order to verify the approach in a test bed withusers connected from heterogeneous networks.