Streaming and Synchronization of Multi-User Worlds Through HTTP/1.1
Abstract
As the trend of online multi-user worlds gets more and more momentum, such worlds usually require heavy infrastructures both in terms of hardware and software: servers often manage the entire world simulation, and hence limit the number of simultaneous connections. The data exchanges are performed using proprietary protocols, requiring specific server applications and the use of dedicated ports which leads to potentially complex proxy issues for connection. Also, online virtual worlds usually target specific plat forms (e.g. PC for Second Life, or game stations for Playstation Home), and even reduce the use of the world to a subset of available platforms due to bandwidth or hardware requirements. We propose an approach for adaptive streaming of online multi-user virtual worlds, using generic transfer protocols and a unified representation of the worlds usable on an arbitrary wide range of platforms. HTTP/1.1 natively supports two crucial features for data streaming: persistent connections and chunked access to files. We leverage those capabilities to avoid the need for specific server software, communication ports and transfer protocols. Also, a side effect of the use of HTTP/1.1 is an enhancement of the usability: most current proxies support this protocol, hence sparing the user a specific tuning of proxies and firewalls. Based on those simple capabilities we propose unified representations of arbitrarily large virtual worlds based on X3D, as well as methods for adaptive streaming and interaction regarless of the net work bandwidth or capabilities of the client hardware.