Assessing Structured Peer-to-Peer Overlays for Network Virtual Environments |
Network virtual environments (NVE) are an evolving trend combining millions of users in an interactive large-scare community. A distributed NVE platform promises to lower the administration costs and to benefit from research done in the peer-to-peer (p2p) domain. In the domain of p2p, research issues such as stability, scalability, load balancing, and robustness had been addressed as well. In order to reuse existing mature p2p overlays for NVEs, a comparative evaluation has to be done in the same environment (e.g. resources of peers, peer behavior, churn, etc.), using appropriate test cases (scenarios) and observing relevant performance metrics. In this paper we present a benchmarking approach for p2p overlays in the context of NVEs. We define NVE related quality attributes, scenarios, and metrics and use them to evaluate Chord and Kademlia as most popular p2p overlays and assess their suitability to NVE. We identify some mechanisms in Kademlia as very useful for NVEs and lay the basis for further comparable evaluations of overlays for the use for NVEs. |
CSLive: A Live Streaming Overlay with Cooperative Swarming |
Peer-to-peer (P2P) live streaming systems gain a lot of attention recently. Among the various architectures, the gossip-based approach holds great potential and has been used in real systems. In a gossip-based P2P streaming system, peer nodes are grouped together to exchange pieces of the live stream with each other. Maintaining the group and pulling the streaming data from other peers incur nontrivial overhead. This paper proposes CSLive, a P2P streaming system which gathers nodes that have good network proximity into clusters and lets nodes in the same cluster cooperate with each other to pull the stream. Each node in the cluster is responsible for pulling a subset of the stream, while pushing the subset to other nodes in the cluster. With the cooperative operations, a node can receive most streaming data from other nodes in the same cluster, which have good communication quality. The proposed system is evaluated with simulation. |
Delaunay State Management for Large-Scale Networked Virtual Environments |
Peer-to-Peer (P2P) network has been proposed as one promising approach to provide better scalability for Networked Virtual Environment (NVE) systems, but P2P-NVE also increases the probability of cheating by allowing users to manage the states of objects. We propose Delaunay State Management (DSM), a P2P-NVE state management scheme that divides the whole virtual world into many triangular regions by Delaunay triangulation. Each region is managed by three super-peers, whose collective decisions detrmine how states will change. Assuming that at most one of the three super-peers is malicious, effective anti-cheating can be provided. Additionally, we also describe how DSM provides the essential features for a state management system, such as consistency, load-balancing, and fault-tolerance. Finally, we discuss some of DSM's potential applications. |
DualCast: Protocol Design of Multiple Shared Trees Based Application Layer Multicast |
This paper introduces a new approach to build application layer multicast overlay --- Multiple Shared Trees. Multiple shared trees' approach makes tradeoffs between traditional source-based trees and single-shared tree, and between transmission efficiency and protocol overheads. Based on this, we propose two protocols to build ALM overlay among end users and media-forwarding-gateways respectively. The latter references the design thought of Aggregated Multicast to share the multicast trees among groups. |
Enhancing the Performance of Locating Data in Chord-based P2P |
In peer-to-peer (P2P)
networks, how to efficiently locate data on distributed hash tables (DHTs)
is challenging and has attracted much research attention in recent
years. Two measurements are usually considered when discussing the
efficient location of data items: the path length (the hop count for
resolving a lookup request on the overlay network) and the latency |
Framework for Scalable Virtual Worlds using Spatially Organized P2P Networks |
The general craze for virtual environments, the potential of augmented reality applications and the announced revolution of the Internet world (Web 2.0, Web 3D.0) are key points for the emergence of an 'ambient' Web which will make it possible for users to communicate, collaborate, entertain, work and exchange content. In this context, content storage, delivery, and reproduction are among the essential points for the deployment of a highly scalable platform of wide reality. In this paper, we propose a self-scalable peer-to-peer architecture for the navigation in network-based virtual worlds. To reach this goal, we propose a fully distributed and adaptive streaming method that quickly adapts the reproduced content according to user interaction. Our content delivery strategy has been implemented and tested on a dedicated simulator with a large 3D city model. The presented results show the efficiency of our strategy in very critical conditions. |
GP3 - A Distributed Grid-based Spatial Index Infrastructure for Massive Multiuser Virtual Environments |
Massive Multiuser Virtual Environments (MMVEs) and especially the idea of a ''3D Web'' as a combination of a MMVE and today's WWW currently attracts a lot of attention. The realization of such a vision on a global scale though poses severe technical challenges to the underlying network infrastructure. It is generally accepted that such a global scale scenario can only be realized in a distributed fashion. The HyperVerse project aims at the provision of a federated global scalable infrastructure for such a ''3D Web'' scenario. We propose a two-tier Peer-to-Peer infrastructure that combines a loosely structured overlay network of user clients with a highly-structured overlay network of reliable so-called Public Servers constituting the backbone of our architecture. This paper presents the Grid-based Plane Partitioning Protocol (GP3), a structured Peer-to-Peer overlay network for the interconnection of the Public Servers that realizes a spatial index in order to allow fast location based queries. |
GROUP: Dual-Overlay State Management for P2P NVE |
Peer-to-peer (P2P) architectures have recently become a popular design choice to build scalable Networked Virtual Environments (NVEs). While P2P architectures offer better scalability than server-based architectures, efficient distribution and management of avatar and object states remains a highly challenging issue. In this paper, we propose GROUP, a fully-distributed P2P architecture for NVEs that addresses this issue by combining a structured P2P overlay, used for object state management, with a Voronoi-based overlay, used for avatar state and group membership management. The resulting dual overlay architecture enables efficient and fully distributed management of state updates for P2P-based NVEs. |
Measures for Inconsistency in Distributed Virtual Environments |
In distributed virtual environments, hosts typically have to react to events within a time span which is less than the network latency. As a consequence, hosts do routinely take actions although the system is in an inconsistent state. This has a noticeable influence on the perceived quality of these actions and their effect on the application. We argue that the level of this influence depends on the degree of inconsistency. In this paper, we tackle two fundamental questions: How does the degree of inconsistency influence the perceived quality of the users' actions? How can the degree of inconsistency be quantified? We propose a benchmark test for comparing different consistency algorithms with each other which consists of two measures of inconsistency and a sample scenario. For two different consistency algorithms, we compare the results of our benchmark test with the results of a user evaluation test and a simple yield measure. |
NL-DHT: A Non-uniform Locality Sensitive DHT Architecture for Massively Multi-user Virtual Environment Applications |
DHT networks offer a
scalable structure for use in massively multi-user virtual environments
(MMVEs). However, an issue with DHT structures is their use of uniform
location-independent ID assignment. This conflicts with the
locality-sensitive non-uniform ID assignment needed to achieve efficient
latency-aware routing in MMVE applications. Our proposed solution is to
use a modified version of the Hilbert space-filling curve in order to
map users locations from three dimensional VE space into single
dimensional DHT ID space in the best locality preserving way. The need
for such modified Hilbert curve is due to the fact that users are not
typically homogeneously distributed in MMVEs while Hilbert curves fill
space in a uniform manner. |
Peer-to-Peer based Version Control |
Many software projects are developed by globally distributed
teams. The nature of the peer-to-peer paradigm fits to such an
application scenario. However, existing tools to support developer
require a central instance, like it is the case in version control, which is crucial for software development. This paper address the challenges version control faces in a purely peer-to-peer environment and presents a peer-to-peer based version control system we developed. We will evolve this basic approach, adding more features like change-set version control. |
Plug: Virtual Worlds for Millions of People |
We propose the design of Plug, an application to find and keep contacts with friends within many inter-connected 3D virtual worlds. Users use an instant messenger (IM)-like interface to converse with friends and find new contacts, using a virtual representation of the user's self. It consists of three parts: a plug is an automatous agent / avatar situated at a user's computer that reflects and mimics its owner's behaviors and interests; a plugspace is a virtual environment that can be inter-connected, with scales ranging from a room to an entire virtual universe; and plugtalk is a set of packet formats and protocols that allow plugspaces to inter-connect, and individual plugs to navigate. Plug utilizes standards whenever possible, and is designed to be scalable, extensible, and customizable for various uses such as distance learning, virtual shopping, or online gaming. By combining the looks of 3D virtual worlds and the accessibility of IMs, we envision Plug as a step towards common virtual world experiences sharable by all Internet users. |
Quality of Service for Peer-to-Peer based Networked Virtual Environments |
This paper describes
how Quality of Service (QoS) enabled Overlay Multicast architectures
using Peer-to-Peer (P2P) networks can enhance the experience of
end-users in Networked Virtual Environments (NVE). |
Query Optimisation in a Virtual Cinema Environment |
Traditional sensor network deployments consisted of fixed infrastructures and were relatively small in size. More and more, we see the deployment of ad-hoc sensor networks with heterogeneous devices on a larger scale, posing new challenges for device management and query processing. In this paper, we present our design and prototype implementation of XSense, an architecture supporting metadata and query services for an underlying large scale dynamic P2P sensor network. We cluster sensor devices into manageable groupings to optimise the query process and automatically locate appropriate clusters based on keyword abstraction from queries. We present experimental analysis to show the benefits of our approach and demonstrate improved query performance and scalability. |
Textures in Second Life: Measurement and Analysis |
We collected packet traces from Second Life client sessions and analyzed the packet contents. We observed that textures constitute a majority of the network traffic. We further characterized the textures from three selected regions in Second Life in terms of their size and spatial distributions. We found that textures in these regions exhibit a different size distribution from files on a file system or documents on the Web. We also verified the intuition that texture objects are spatially non-uniformly distributed. Surprisingly, we found that the selected Second Life regions can contain up to hundreds of megabytes of textures, and there exist locations in these regions that encompass a large portion of these textures within their area-of-interest. Our work motivates the need to manage textures carefully and efficiently in the design of networked virtual environments such as Second Life, and hints at the amount of storage and bandwidth required at a peer if peer-to-peer techniques are applied for texture caching. Our traces are useful for simulation studies and can lead to a model to generate realistic workload for networked virtual environments. |
2008 International Workshop on Peer-to-Peer Networked Virtual Environments
(P2P-NVE 2008)
Last modified at 2008/10/10