Tag Archives: 2015

DynFilter: Limiting Bandwidth of Online Games using Adaptive Pub/Sub Message Filtering

Gascon-Samson, J., Kienzle, J., Kemme, B. DynFilter: Limiting Bandwidth of Online Games using Adaptive Pub/Sub Message Filtering, NetGames 2015, Zagreb, Croatia
[Preprint] [Presentation Slides]

Abstract: Multiplayer online games can generate a lot of server-related outgoing bandwidth, due to many factors such as highly variable amounts of players or the gathering of many players towards the same in-game locations. Predicting the exact amount of required bandwidth to support varying conditions can be costly, and players can experience game-wide failures if bandwidth is insufficiently provisioned. We present DynFilter, a game-oriented message processing middleware designed to adaptively filter state update messages for in-game entities located apart, in order to reduce bandwidth needs and stay within predefined quotas. We ran experiments on Amazon EC2 over a prototype game mimicking a FPS and a MMOG. Our results show that DynFilter is properly able to maintain bandwidth use within the pre-established quotas while still maintaining adequate delivery of relevant state update messages.

Dynamoth: A Scalable Pub/Sub Middleware for Latency-Constrained Applications in the Cloud

Gascon-Samson, J., Garcia, F.-P., Kemme, B., Kienzle, J. (2015) Dynamoth: A Scalable Pub/Sub Middleware for Latency-Constrained Applications in the Cloud, ICDCS 2015, Columbus, USA
> Acceptance ratio: 12.8% [Preprint] [Presentation Slides]

Abstract: This paper presents Dynamoth, a dynamic, scalable, channel-based pub/sub middleware targeted at large scale, distributed and latency constrained systems. Our approach provides a software layer that balances the load generated by a high number of publishers, subscribers and messages across multiple, standard pub/sub servers that can be deployed in the Cloud. In order to optimize Cloud infrastructure usage, pub/sub servers can be added or removed as needed. Balancing takes into account the live characteristics of each channel and is done in an hierarchical manner across channels (macro) as well as within individual channels (micro) to maintain acceptable performance and low latencies despite highly varying conditions. Load monitoring is performed in an unintrusive way, and rebalancing employs a lazy approach in order to minimize its temporal impact on performance while ensuring successful and timely delivery of all messages. Extensive real-world experiments that illustrate the practicality of the approach within a massively multiplayer game setting are presented. Results indicate that with a given number of servers, Dynamoth was able to handle 60% more simultaneous clients than the consistent hashing approach, and that it was properly able to deal with highly varying conditions in the context of large workloads.

Monitoring Large-Scale Location-Based Information Systems

Khan, H., Gascon-Samson, J., Kienzle, J., Kemme, B. (2015) Monitoring Large-Scale Location-Based Information Systems, IPDPS 2015, Hyderabad, India
> Acceptance ratio: 22% [Preprint]

Abstract: Monitoring the state of a distributed virtual world is challenging for several reasons: 1) the distributed information must be gathered in real-time without affecting the performance of the information system, 2) in large-scale systems it is impossible for a single node to collect and process all the data, 3) the vast information must be filtered and aggregated according to what the human observer wants to focus on, and 4) the point of interest of the observer can change frequently. In this paper we present and evaluate a non-intrusive monitoring middleware that addresses these challenges by dynamically partitioning the geographic map (e.g., of the virtual world or the game) in terms of map objects and (expected) state changes. We assign a different collector node to each of these partitions to collect and pre-process the data, and forward it to a central monitoring node. Furthermore, we provide mechanisms to efficiently filter and aggregate location changes, the pre-dominant changes in location-based information systems. We describe a specific monitoring setup that takes advantage of the replication model that is common in many virtual worlds and multiplayer games to collect the data. Finally, we present extensive performance results that show the trade-offs between scalability, precision, and real-time performance.