896 research outputs found
Analysis domain model for shared virtual environments
The field of shared virtual environments, which also
encompasses online games and social 3D environments, has a
system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model
A Survey on Load Balancing Algorithms for VM Placement in Cloud Computing
The emergence of cloud computing based on virtualization technologies brings
huge opportunities to host virtual resource at low cost without the need of
owning any infrastructure. Virtualization technologies enable users to acquire,
configure and be charged on pay-per-use basis. However, Cloud data centers
mostly comprise heterogeneous commodity servers hosting multiple virtual
machines (VMs) with potential various specifications and fluctuating resource
usages, which may cause imbalanced resource utilization within servers that may
lead to performance degradation and service level agreements (SLAs) violations.
To achieve efficient scheduling, these challenges should be addressed and
solved by using load balancing strategies, which have been proved to be NP-hard
problem. From multiple perspectives, this work identifies the challenges and
analyzes existing algorithms for allocating VMs to PMs in infrastructure
Clouds, especially focuses on load balancing. A detailed classification
targeting load balancing algorithms for VM placement in cloud data centers is
investigated and the surveyed algorithms are classified according to the
classification. The goal of this paper is to provide a comprehensive and
comparative understanding of existing literature and aid researchers by
providing an insight for potential future enhancements.Comment: 22 Pages, 4 Figures, 4 Tables, in pres
Application of Web Services to a Simulation Framework
The Joint Semi-Automated Forces (JSAF) simulator is an excellent tool for military training and a great testbed for new SAF behaviors. However, it has the drawback that behaviors must be ported into its own Finite State Machine (FSM) language. Web Services is a growing technology that seamlessly connects service providers to service consumers. This work attempts to merge these two technologies by modeling SAF behaviors as web services. The JSAF simulator is then modeled as a web service consumer. This approach allows new Semi-Automated Forces (SAF) behaviors to be developed independently of the simulator, which provides the developer with greater ïŹexibility when choosing a programming language, development environment, and development platform. In addition to new SAF behaviors, this approach also supports any external component that can be modeled as a web service. Furthermore, these services are often run over a network, which distributes the computational load across several computers. Finally, hosting copies of a single service on several machines, a concept similar to ïŹle-sharing mirrors, oïŹers an environment for load-balancing. This means if several entities are running the same behavior, a single server does not perform the computation for every entity. Instead, each entity is assigned to a speciïŹc server, increasing the quality of service seen by the system. A Web Services framework linking JSAF with several services is designed and implemented. Suppression of Enemy Air Defense (SEAD) behaviors written in MATLAB and a behavior recognition system are integrated with JSAF. These behaviors and the recognition tool were developed by other researchers, independent of this work. Results show that oïŹoading computation to other machines is beneïŹcial, especially when the simulation system is under heavy load. Preliminary results also indicate that load-balancing performs much better than using a single server
Hybrid Simulation and Test of Vessel Traffic Systems on the Cloud
This paper presents a cloud-based hybrid simulation platform to test large-scale distributed System-of-Systems (SoS) for the management and control of maritime traffic, the so-called Vessel Traffic Systems (VTS). A VTS consists of multiple, heterogeneous, distributed and interoperating systems, including radar, automatic identification systems, direction finders, electro-optical sensors, gateways to external VTSs, information systems; identifying, representing and analyzing interactions is a challenge to the evaluation of the real risks for safety and security of the marine environment. The need for reproducing in fabric the system behaviors that could occur in situ demands for the ability of integrating emulated and simulated environments to cope with the different testability requirements of involved systems and to keep testing cost sustainable. The platform exploits hybrid simulation and virtualization technologies, and it is deployable on a private cloud, reducing the cost of setting up realistic and effective testing scenarios
On network latency in distributed interactive applications
This paper has three objectives. Firstly it describes the historical development of Distributed Interactive Applications. It then defines network latency. Finally it describes a new approach to masking network latency in Distributed Interactive Applications called the strategy model approach. This approach derives from the on-going PhD studies of one of the authors. A software application to gather strategy data from users is described in detail and an example of deriving a user strategy is given
Agents for educational games and simulations
This book consists mainly of revised papers that were presented at the Agents for Educational Games and Simulation (AEGS) workshop held on May 2, 2011, as part of the Autonomous Agents and MultiAgent Systems (AAMAS) conference in Taipei, Taiwan. The 12 full papers presented were carefully reviewed and selected from various submissions. The papers are organized topical sections on middleware applications, dialogues and learning, adaption and convergence, and agent applications
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
iii
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
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
iii
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
A Collaborative Software Infrastructure based on the High Level Architecture and XML
A study is made of using the High Level Architecture (HLA) as foundation for distributed applications in the domain of Computer-Supported Collaborative Work. A plug-in, peer-to-peer infrastructure for such applications is proposed, aimed at facilitating development and management of collaborative software. Users of the framework collaborate in groups and sessions, described by a replicated state XML information model. A prototype infrastructure is developed, along with three prototype collaborative applications. Results of performance testing show that a transport system built on HLA compares reasonably well with a socket-based transport system. On the whole, results demonstrate feasibility of the infrastructure and of the objective of extending the HLA to non-simulation applications. Future work to adapt full-scale applications to the collaborative infrastructure is invited
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