The document proposes a solution to enable context entity discovery in an Internet of Things (IoT) platform. It introduces a publish/subscribe approach using a rendezvous node as an initial publisher of a global Universal Context Identifier (UCI). Entities subscribe to this by default. Two new messages, joinUCI and DISCOVER, are added to the Distributed Context eXchange Protocol (DCXP) to allow entities to join and discover existing UCIs. Evaluation shows the extended DCXP achieves context entity discovery on par with the original protocol but can scale to larger networks.