999 research outputs found
LUNES: Agent-based Simulation of P2P Systems (Extended Version)
We present LUNES, an agent-based Large Unstructured NEtwork Simulator, which
allows to simulate complex networks composed of a high number of nodes. LUNES
is modular, since it splits the three phases of network topology creation,
protocol simulation and performance evaluation. This permits to easily
integrate external software tools into the main software architecture. The
simulation of the interaction protocols among network nodes is performed via a
simulation middleware that supports both the sequential and the
parallel/distributed simulation approaches. In the latter case, a specific
mechanism for the communication overhead-reduction is used; this guarantees
high levels of performance and scalability. To demonstrate the efficiency of
LUNES, we test the simulator with gossip protocols executed on top of networks
(representing peer-to-peer overlays), generated with different topologies.
Results demonstrate the effectiveness of the proposed approach.Comment: Proceedings of the International Workshop on Modeling and Simulation
of Peer-to-Peer Architectures and Systems (MOSPAS 2011). As part of the 2011
International Conference on High Performance Computing and Simulation (HPCS
2011
Mobile Online Gaming via Resource Sharing
Mobile gaming presents a number of main issues which remain open. These are
concerned mainly with connectivity, computational capacities, memory and
battery constraints. In this paper, we discuss the design of a fully
distributed approach for the support of mobile Multiplayer Online Games (MOGs).
In mobile environments, several features might be exploited to enable resource
sharing among multiple devices / game consoles owned by different mobile users.
We show the advantages of trading computing / networking facilities among
mobile players. This operation mode opens a wide number of interesting sharing
scenarios, thus promoting the deployment of novel mobile online games. In
particular, once mobile nodes make their resource available for the community,
it becomes possible to distribute the software modules that compose the game
engine. This allows to distribute the workload for the game advancement
management. We claim that resource sharing is in unison with the idea of ludic
activity that is behind MOGs. Hence, such schemes can be profitably employed in
these contexts.Comment: Proceedings of 3nd ICST/CREATE-NET Workshop on DIstributed SImulation
and Online gaming (DISIO 2012). In conjunction with SIMUTools 2012.
Desenzano, Italy, March 2012. ISBN: 978-1-936968-47-
A novel scalable hybrid architecture for MMOG
We present a novel MMOG Hybrid P2P architecture and detail its key components, topology and protocols. We highlight the main components which lie at the heart of the proposed solution, and their roles, and describe the methods of tackling the key scenarios which are faced by the architecture during gameplay. For each role, we discuss the interactions that exist between them and describe the protocols that will be used for inter-role communication to perform the atomic actions necessary for maintaining the consistency and responsiveness of an MMOG such as peer addition, peer removal, group transfer, object change persistency and many more. We conclude the chapter with a comparison of the architecture against several existing P2P MMOG frameworks, discussing the differences which exist between them and how the novel Hybrid-P2P architecture we propose aims to address their flaws
Design Issues for Peer-to-Peer Massively Multiplayer Online Games.
Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and scale, and while classical Client/Server (C/S) architectures convey some benefits, they suffer from significant technical and commercial drawbacks. This realisation has sparked intensive research interest in adapting MMOGs to Peer-to-Peer (P2P) architectures. This paper articulates a comprehensive set of six design issues to be addressed by P2P MMOGs, namely Interest Management (IM), game event dissemination, Non-Player Character (NPC) host allocation, game state persistency, cheating mitigation and incentive mechanisms. Design alternatives for each issue are systematically compared, and their interrelationships discussed. We further evaluate how well representative P2P MMOG architectures fulfil the design criteria
Parallel and Distributed Simulation from Many Cores to the Public Cloud (Extended Version)
In this tutorial paper, we will firstly review some basic simulation concepts
and then introduce the parallel and distributed simulation techniques in view
of some new challenges of today and tomorrow. More in particular, in the last
years there has been a wide diffusion of many cores architectures and we can
expect this trend to continue. On the other hand, the success of cloud
computing is strongly promoting the everything as a service paradigm. Is
parallel and distributed simulation ready for these new challenges? The current
approaches present many limitations in terms of usability and adaptivity: there
is a strong need for new evaluation metrics and for revising the currently
implemented mechanisms. In the last part of the paper, we propose a new
approach based on multi-agent systems for the simulation of complex systems. It
is possible to implement advanced techniques such as the migration of simulated
entities in order to build mechanisms that are both adaptive and very easy to
use. Adaptive mechanisms are able to significantly reduce the communication
cost in the parallel/distributed architectures, to implement load-balance
techniques and to cope with execution environments that are both variable and
dynamic. Finally, such mechanisms will be used to build simulations on top of
unreliable cloud services.Comment: Tutorial paper published in the Proceedings of the International
Conference on High Performance Computing and Simulation (HPCS 2011). Istanbul
(Turkey), IEEE, July 2011. ISBN 978-1-61284-382-
Solving key design issues for massively multiplayer online games on peer-to-peer architectures
Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and
scale on the Internet and are predominantly implemented by Client/Server architectures.
While such a classical approach to distributed system design offers many benefits, it suffers
from significant technical and commercial drawbacks, primarily reliability and scalability
costs. This realisation has sparked recent research interest in adapting MMOGs
to Peer-to-Peer (P2P) architectures.
This thesis identifies six key design issues to be addressed by P2P MMOGs, namely
interest management, event dissemination, task sharing, state persistency, cheating mitigation,
and incentive mechanisms. Design alternatives for each issue are systematically
compared, and their interrelationships discussed. How well representative P2P MMOG
architectures fulfil the design criteria is also evaluated. It is argued that although P2P
MMOG architectures are developing rapidly, their support for task sharing and incentive
mechanisms still need to be improved.
The design of a novel framework for P2P MMOGs, Mediator, is presented. It employs a
self-organising super-peer network over a P2P overlay infrastructure, and addresses the
six design issues in an integrated system. The Mediator framework is extensible, as it
supports flexible policy plug-ins and can accommodate the introduction of new superpeer
roles. Key components of this framework have been implemented and evaluated
with a simulated P2P MMOG.
As the Mediator framework relies on super-peers for computational and administrative
tasks, membership management is crucial, e.g. to allow the system to recover from
super-peer failures. A new technology for this, namely Membership-Aware Multicast
with Bushiness Optimisation (MAMBO), has been designed, implemented and evaluated.
It reuses the communication structure of a tree-based application-level multicast
to track group membership efficiently. Evaluation of a demonstration application shows
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that MAMBO is able to quickly detect and handle peers joining and leaving. Compared
to a conventional supervision architecture, MAMBO is more scalable, and yet incurs
less communication overheads. Besides MMOGs, MAMBO is suitable for other P2P
applications, such as collaborative computing and multimedia streaming.
This thesis also presents the design, implementation and evaluation of a novel task
mapping infrastructure for heterogeneous P2P environments, Deadline-Driven Auctions
(DDA). DDA is primarily designed to support NPC host allocation in P2P MMOGs, and
specifically in the Mediator framework. However, it can also support the sharing of computational
and interactive tasks with various deadlines in general P2P applications. Experimental
and analytical results demonstrate that DDA efficiently allocates computing
resources for large numbers of real-time NPC tasks in a simulated P2P MMOG with approximately
1000 players. Furthermore, DDA supports gaming interactivity by keeping
the communication latency among NPC hosts and ordinary players low. It also supports
flexible matchmaking policies, and can motivate application participants to contribute
resources to the system
Highly intensive data dissemination in complex networks
This paper presents a study on data dissemination in unstructured
Peer-to-Peer (P2P) network overlays. The absence of a structure in unstructured
overlays eases the network management, at the cost of non-optimal mechanisms to
spread messages in the network. Thus, dissemination schemes must be employed
that allow covering a large portion of the network with a high probability
(e.g.~gossip based approaches). We identify principal metrics, provide a
theoretical model and perform the assessment evaluation using a high
performance simulator that is based on a parallel and distributed architecture.
A main point of this study is that our simulation model considers
implementation technical details, such as the use of caching and Time To Live
(TTL) in message dissemination, that are usually neglected in simulations, due
to the additional overhead they cause. Outcomes confirm that these technical
details have an important influence on the performance of dissemination schemes
and that the studied schemes are quite effective to spread information in P2P
overlay networks, whatever their topology. Moreover, the practical usage of
such dissemination mechanisms requires a fine tuning of many parameters, the
choice between different network topologies and the assessment of behaviors
such as free riding. All this can be done only using efficient simulation tools
to support both the network design phase and, in some cases, at runtime
VCube-PS: A Causal Broadcast Topic-based Publish/Subscribe System
In this work we present VCube-PS, a topic-based Publish/Subscribe system
built on the top of a virtual hypercube-like topology. Membership information
and published messages are broadcast to subscribers (members) of a topic group
over dynamically built spanning trees rooted at the publisher. For a given
topic, the delivery of published messages respects the causal order. VCube-PS
was implemented on the PeerSim simulator, and experiments are reported
including a comparison with the traditional Publish/Subscribe approach that
employs a single rooted static spanning-tree for message distribution. Results
confirm the efficiency of VCube-PS in terms of scalability, latency, number and
size of messages.Comment: Improved text and performance evaluation. Added proof for the
algorithms (Section 3.4
Middleware services for distributed virtual environments
PhD ThesisDistributed Virtual Environments (DVEs) are virtual environments which allow
dispersed users to interact with each other and the virtual world through the
underlying network.
Scalability is a major challenge in building a successful DVE, which is directly
affected by the volume of message exchange. Different techniques have been
deployed to reduce the volume of message exchange in order to support large
numbers of simultaneous participants in a DVE. Interest management is a
popular technique for filtering unnecessary message exchange between users.
The rationale behind interest management is to resolve the "interests" of users
and decide whether messages should be exchanged between them. There are
three basic interest management approaches: region-based, aura-based and
hybrid approaches. However, if the time taken for an interest management
approach to determine interests is greater than the duration of the interaction, it
is not possible to guarantee interactions will occur correctly or at all. This is
termed the Missed Interaction Problem, which all existing interest management
approaches are susceptible to.
This thesis provides a new aura-based interest management approach, termed
Predictive Interest management (PIM), to alleviate the missed interaction
problem. PIM uses an enlarged aura to detect potential aura-intersections and
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initiate message exchange. It utilises variable message exchange frequencies,
proportional to the intersection degree of the objects' expanded auras, to restrict
bandwidth usage. This thesis provides an experimental system, the PIM system,
which couples predictive interest management with the de-centralised server
communication model. It utilises the Common Object Request Broker
Architecture (CORBA) middleware standard to provide an interoperable
middleware for DVEs. Experimental results are provided to demonstrate that
PIM provides a scalable interest management approach which alleviates the
missed interaction problem
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