SPEX: scalable spatial publish/subscribe for distributed virtual worlds without borders

Existing architectures designed to host large-scale virtual environments (VEs) use a variety of approaches, but they often limit the interaction range with other users or with the VE. How densely users can populate a given region is also limited by the hosting machine's CPU or bandwidth resources. We are motivated to remove such restrictions and present SPEX, an infrastructure that supports scalable spatial publish/subscribe for VE applications. SPEX is scalable and fault-tolerant, with adaptive load balancing and low latency as its key features. It is designed for the state and overlay management in VEs with many concurrent users. We evaluate a practical SPEX implementation within Amazon's EC2 Cloud and present a feasible approach to supporting 750 users across a continent with low latency, opening the possibility for hosting fast-paced games (e.g., first-person shooters) or applications on a large-scale.