Active Proxy Server
Artery: A Distributed System for Network Games
Group Members:
Project Description:
The goal of the Artery project is to simplify the development
of interactive network games while optimizing the network performance
by taking advantage of the semantics of network game
applications. Typically these games assume a shared database visible to
every participant, and the database
state evolves in response to
the actions of individual players. The rules or behaviors
of particular games define the mapping
between the participants' actions and the impacts on the state of the
shared database.
To improve the performance, the shared database
state must be partially or fully replicated at each participant's site.
At the same time, a coherent world abstraction must be presented
at all times
to participants who may be geographically distributed
across a communication network.
Such an abstraction ensures that users
share the sense of logically being in a single world although
they are physically in different geographical areas.
Artery attempts to replace socket-based communications
with a shared-memory programming
interface to network game developers, much like the advancement in the
parallel programming arena. Artery supports the following
performance optimization features:
- Dead Reckoning: The trajectories of simulation entities are
predicted all the time at the relevant nodes to eliminate messages
for predictable position/speed updates. Clock synchronization
may be required for trajectory prediction to work correctly
across the network.
- Dyanmic Group Consistency Model: Only events that are within
the sensing range of a simulation entity need to be
propagated to the node acting on behalf of the entity.
- Packet Aggregation: Packets are aggregated to improve the
efficiency of network transmission.
- Synchronous Reliable IP Multicast: The packet multicast
mechanism must be reliable and synchronous, i.e., packets reaching
to all nodes reliably and approximately the same time. In addition,
the group membership change should be fast.
Publications:
- Tzi-cker Chiueh, "Distributed Systems Support for Networked Games,"
in Proceedings of HotOS V Workshop, Cape Cod, MA, May 1997.
- Tzi-cker Chiueh, Allen Ballman, Prashant Pradhan,
"Distributed
System Support for Network-Based Multi-User Interactive
Applications," in Proceedings of 1st Distributed Simulation
Symposium '97, Orlando, FL, September 1997.