Latency and scalability: a survey of issues and techniques for supporting networked games

The popularity of on-line games that emphasize real-time interactivity is on the rise. A survey of issues and techniques for supporting on-line games is provided in this paper. Latency and scalability are two primary aspects on which this survey is based. Network latency heavily influences the design of on-line games with regards to the nature of interactivities involved, as well as, real-time flows such as voice and video if enhanced user immersive experiences are required. As a consequence, a trade-off between consistency and responsiveness, the two latency-related artifacts, is usually needed. This can be demonstrated through a number of latency compensation techniques presented in this paper, including the synchronization and optimistic approaches. To address the drawbacks of the current predominant client-server model, scalable architectures usually achieve scalability through the partition of either the physical or virtual world. In the case of distributed server design, this has resulted in systems such as the locale or proxy server architecture. In the peer-to-peer design, in addition to partition, hybrid system introduces the concept of 'super node' to allow the manageability in the overlay network. The latest peer-to-peer design emphasizes a structured approach such as the Pastry. Although such a design is not targeted for latency constraint applications, due to its unique features, experiments on hosting networked games on structured peer-to-peer network start to emerge.