Towards efficient publish-subscribe middleware in the IoT with IPv6 multicast

Due to its scale and dynamism, the Internet of Things (IoT) requires efficient and flexible communication support. At the network layer, IPv6 integrates heterogeneous technologies to provide interoperability, efficient multicast group communication and a flexible address space. At the application layer, publish-subscribe (pub-sub) middleware implements a scalable, dynamic and loosely-coupled data dissemination scheme. The pub-sub paradigm is a natural use case for IPv6 multicast but the two mechanisms are poorly integrated in the IoT. We tackle this problem by proposing a framework that enables the integration of pub-sub middleware and multicast to reduce communication overhead. Our solution maps application-layer subscriber groups to network-layer multicast groups. Pub-sub hosts can either implicitly derive the necessary multicast address or request it from a group manager. We evaluate our framework on an IoT network testbed composed of representative hardware and demonstrate improvements in bandwidth and energy consumption that scale with the size of the network: bandwidth consumption of a publishing sensor decreases by up to 54% for 10 subscribers and 66% for 20 subscribers. Moreover, the implementation has a minimal memory footprint, requiring only an additional 1.3% dynamic memory and 4.7% flash storage.status: publishe

Towards a fully mobile publish/subscribe system

93 p.This PhD thesis makes contributions to support mobility and fault tolerance in a publish/subscribe system. Two protocols are proposed in order to support mobility of all devices in the system, including inside the event notification service. The protocols are designed with the idea that any change due to mobility is completely beyond our control and ability to predict. Moreover, the proposed solutions do not need to know neither the amount of nodes in the system nor their identities before starting, the system is able to adapt to new devices or disconnections and is able to keep operating correctly in a partitioned network. To do so we extend a previously proposed framework called Phoenix that already supported client mobility. Both protocols use a leader election mechanism to create a communication tree in a highly dynamic environment, and use a characteristic of that algorithm to detect topology changes and migrate nodes accordingly