ePulsar: Control Plane for Publish-Subscribe Systems on Geo-Distributed Edge Infrastructure

Emerging applications such as autonomous drones and massively multiplayer gaming require real-time communication between multiple geo-distributed participating entities. A publish-subscribe system deployed on a geo-distributed edge infrastructure would provide a scalable messaging middleware for such applications. However state-of-the-art publish-subscribe systems like Apache Pulsar and Kafka perform inefficiently in a geo-distributed deployment due to heterogeneous client-broker latencies and constant client mobility. We present a novel control-plane architecture for geo-distributed publish-subscribe systems that is capable of adaptive topic partitioning to enable low-latency messaging for such applications. We leverage a peer-to-peer network coordinate protocol for scalable estimation of network latencies between publish-subscribe brokers and clients. Client-broker latency and workload metrics are continuously collected from brokers and used to detect latency violations or workload imbalance, which triggers reassignment of topics. We develop ePulsar, which incorporates the control-plane architecture ideas into the popular Apache Pulsar publish-subscribe system, retaining Pulsar's data-plane APIs. We evaluate the efficacy and overheads of the proposed control plane using workload scenarios representative of typical edge-centric applications on an emulated geo-distributed infrastructure.