A Context-Aware Middleware for FL-Enabled Collaboration in IoT-Enhanced Communities

The rapid growth of IoT-powered smart communities has created valuable, but siloed data, limited by interoperability and data-sovereignty concerns. We present ComDeX , a context-aware federated IoT middleware that enables selective, intelligent collaboration across communities. ComDeX uses a property-graph data model to encode IoT entities as context-rich pub/sub messages, discovered and filtered via an advertisement-based federation, so communities share only what is relevant while retaining control. To support collaborative intelligence, ComDeX adds a cross-organization Discovery → Eligibility → Enrollment (DEE) layer that enables discovery of FL tasks and clients, independent of the chosen FL runtime. We prototype ComDeX on MQTT and NGSI-LD and evaluate in a smart-port scenario, demonstrating faster and more efficient cross-community exchange than existing NGSI-LD federation approaches. In non-IID FL experiments, we showcase cross-community enrollment capabilities and expose different DEE coordination trade-offs. Overall, ComDeX enables scalable, adaptive collaboration for data sharing and federated model training.