XD (Exchange-deliver): \#a Middleware for Developing Device-to-device Mobile Applications

In this demonstration, we showcase the XD middleware, a framework for expressive multiplexing of application communication streams onto underlying device-to-device communication links. XD allows applications to remain agnostic about which low-level networking stack is actually delivering messages and instead focus on the application-level content and delivery parameters. The IoT space has been flooded with new communication technologies (e.g., BLE, ZigBee, 6LoWPAN) to add to those already available on modern mobile devices (e.g., BLE, WiFi-Direct), substantially increasing the barrier to entry for developing innovative IoT applications. XD presents application developers with a simple publish-subscribe API for sending and receiving data streams, unburdening them from the task of selecting and coordinating communication channels. Our demonstration shows two Android applications, Disseminate and Prophet, running using our XD middleware for communication. We implemented BLE, WiFi Direct with TCP, and WiFi Direct with UDP communication stacks underneath XD.