Conference Paper

Maximising Concurrency and Scalability in a Consistent, Causal, Distributed Virtual Reality System Whilst Minimising the Effect of Network Delays.

Dept. of Cybern., Reading Univ.
DOI: 10.1109/ENABL.1997.630808 Conference: 6th Workshop on Enabling Technologies (WET-ICE '97), Infrastructure for Collaborative Enterprises, 18-20 June 1997, MIT, Cambridge, MA, USA, Proceedings
Source: DBLP

ABSTRACT The development of large scale virtual reality and simulation systems have been mostly driven by the DIS and HLA standards community. A number of issues are coming to light about the applicability of these standards, in their present state, to the support of general multi-user VR systems. This paper pinpoints four issues that must be readdressed before large scale virtual reality systems become accessible to a larger commercial and public domain: a reduction in the effects of network delays; scalable causal event delivery; update control; and scalable reliable communication. Each of these issues is tackled through a common theme of combining wall clock and causal time-related entity behaviour, knowledge of network delays and prediction of entity behaviour, that together overcome many of the effects of network delays.

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Available from: David Roberts, Sep 26, 2015
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    • "In a related work, Roberts and Sharkey [9] describe the use of a sufficient causal ordering for an arena-like distributed virtual reality system named PaRADE [9]. They verified through implementation experiences the performance benefits of using a relaxed mechanism to provide memory consistency over a network. "
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    ABSTRACT: Building collaborative applications is still a challenging task. A collaborative application can be viewed as a class of distributed shared memory system. A distinctive property of these systems is their memory consistency model. In this paper, we argue that there is a relationship between different collaboration styles, on the one hand, and different memory consistency models, on the other. In particular, we propose a practical collaboration style, exemplified by a collaborative electronic organizer, that can be supported by the GWO memory consistency model, a rather relaxed model stricter only that local consistency. The advantage of the proposed style is that it reduces the amount of information that must be exchanged among the processors. Because there have been no propositions of the specific rules – i.e., the protocol – that the processors in a system must follow to implement the GWO model, we also propose a protocol that exactly matches the properties of the model.
    Computing and Informatics 01/2005; 24:53-66. · 0.50 Impact Factor
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    • "• Time Management: Synchronize events or wall clocks among participants. Events can be pre-empted or delayed to maintain consistency [11] [12]. • Priority Scheduling: Data essential to maintaining consistency is sent with the highest priority [13]. "
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    ABSTRACT: Latency and jitter inherently limit the maintenance of consistency in Distributed Interactive Applications such as computer games, distributed whiteboards and real-time, collaborative environments. Although there has been much research into methods for maintaining consistency, there is a distinct lack of research exploring the connection between latency, jitter and the end user experience in Distributed Interactive Applications. We have developed an application that allows us to conduct trials under controlled latency and jitter conditions. This provides data, which can be analysed to characterise how people adapt to various degrees of latency and jitter. We present results that highlight how an increase in latency and jitter affect the end-user experience, thus confirming the need for techniques to combat latency and jitter in Distributed Interactive Applications. We alsoe note that the effects of jitter are significantly greater than those of latency.
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    • "MASSIVE-1 had no support for sub-objects, and MASSIVE-2 had only limited support; this was because of unresolved issues in reasoning about compound objects in the spatial model of interaction. • It should implement proposals for data consistency and ameliorating the effects of network delay from the University of Reading [1]. • It should provide a route to support heterogeneous computers and networks, including domestic users with modem-based connections. "
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    ABSTRACT: MASSIVE-3 is our third generation of Collaborative Virtual Environment (CVE) system. This paper describes the goals, design and implementation of key aspects of the MASSIVE-3 system, and in particular its support for data consistency, and world structuring and interest management. MASSIVE-3 adopts a distributed database model, in which all changes to items in the database are represented by explicit events that are themselves visible to the system. Networking is logically multicast, but physically client-server (the reasons for this are explained). MASSIVE-3 makes application behaviours explicitly visible within the database in the form of "Behaviour" data items. MASSIVE-3 implements and extends work on consistency by the University of Reading. In particular, it adds an explicit "Update Request" data item, which allows the system to support a number of different consistency mechanisms within a single virtual world. World structuring in MASSIVE-3 extends the notion of "Locales" from the SPLINE system to include distinctions based on functional class, organisational scope and fidelity. It also allows flexible and general replication and rendering policies to be specified and used for interest management.
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