Metaverse t o mooc scaling virtual worlds in the cloud
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Metaverse t o MOOC: Scaling Virtual Worlds in the Cloud? PowerPoint PPT Presentation

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Metaverse t o MOOC: Scaling Virtual Worlds in the Cloud?. C.J. Davies Colin Allison Iain Oliver John McCaffery Alan Miller. motivation. MOOCs are open and massive c ope with tens of thousands of learners Open Virtual Worlds (OWV) are open and small

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Metaverse t o MOOC: Scaling Virtual Worlds in the Cloud?

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Metaverse to MOOC:Scaling Virtual Worlds inthe Cloud?

C.J. Davies

Colin Allison

Iain Oliver

John McCaffery

Alan Miller


  • MOOCs are open and massive

    • cope with tens of thousands of learners

  • Open Virtual Worlds (OWV) are open and small

    • can support hundreds at best, often less

  • MOOCs and OVWs are complementary educationally

    • MOOCs consist of static resources for download / streaming / consumption

    • OVWs allow for constructivist multi-user interaction

  • Can the Cloud be used to scale OVWs for MOOCs?

structure of this talk

  • Overview of Open Virtual Worlds at St Andrews

    • example from STEM area of computer networking education

  • What is meant by “Open” and “Massive” ?

  • Methodology

    • design of a benchmark and testbed

  • Measurements

    • metal, virtual machines, Amazon ec2

  • Comments and Conclusions

Open Virtual Worlds @ St Andrews

  • STEM education

    • Internet routing

    • 802.11 wireless protocols

    • Algorithm animation and visualisation

  • Cultural Heritage and Education

    • Digital Tourism, Digital Preservation, Historic Scotland

    • national school curriculum, Education Scotland

    • Archaeology fieldwork training

  • Mobile Cross Reality (see talk on Tuesday,16:00, Heights)

  • Novel User Interfaces

    • Xbox 360, Kinect, commodity-based CAVEs

STEM education example

Internet Routing Protocols

Internet Routing

  • Hierarchical

    • billions of nodes

  • Internet organised into Autonomous Systems

    • AS usually organised into regions

  • Routing between AS: exterior routing

    • usually Border Gateway Protocol (BGPv4)

  • Routing within AS: interior routing

    • Link State or Distance Vector

Fife and Tayside regional network

RNEP: Regional Network Entry Point

POP: Point of Presence

Link from RNEP1 to Abertay is broken (interactively by student)

after watchable protocol exchanges the forwarding table for RNEP1 changes

imagine: an internet core as a hypercube (k=4) rather than a mesh

k=4: visualisation gets tricky in 2D

hypercube k=4

k=4: 3D virtual world visualisation

routing island complements other learning resources

  • two lecture theatres (DV and OSPF)

    • displays content from youtube, web pages and other media

  • document centre (internet standards docs etc)

  • pre-canned simulations of textbook examples

    • Peterson & Davie

    • Tanebaum & Weatherall

    • Kurose & Ross

  • multiple sandbox areas

    • build your own network

document centre

popular youtube video of djikstra’s algorithm

OSPF example from Peterson and Davie

Kurose & Ross Fig. 4.27

What is meant by “Open” ?

UNESCO, 2012

  • “Open Educational Resources (OERs) are any type of educational materials that are in the public domain or introduced with an open license.

  • The nature of these open materials means that anyone can legally and freely copy, use, adapt and re-share them.

  • OERs range from textbooks to curricula, syllabi, lecture notes, assignments, tests, projects, audio, video and animation.”

How Open are MOOCs and OVWs?

  • The UNESCO definition is far more open than most open source licenses

    • “anyone can legally and freely copy, use, adapt and re-share them”

  • MOOC components seemto meet this

  • OVWs:

    • anyone can visit or download an OVW, and then interact with it

    • they can’t necessarily see or take away the underlying code or graphical design

What is meant by “Massive” (i)

  • MOOCs

    • tens of thousands of registered learners

      • aside: less than 10% of participants complete a course

    • asynchronous, one-way: mostly download of prepared resources

      • video streaming, slides, docs, etc.

    • interactive features

      • asynchronous text-based interactive forums

      • online MCQs

What is meant by “Massive”? (ii)

  • Open Virtual Worlds based on OpenSim

    • synchronous interaction, user (avatar) driven, dynamic updates to shared environment

    • at very best hundreds of concurrent avatars

    • also depends on number of prims and complexity of code

      • Routing Island grinds to a standstill with 12 pro-active users carrying out experiments

      • Cathedral mega-region good up to ~ 80 pro-active avatars

Scalability and Variance in Load

  • For asynchronous MOOCs the load can vary but as interaction is always asynchronous frustrated users can simply go away and leave a download running or try again later

  • For synchronous OVWs a transient peak demand can bring a region to a standstill and/or crash the server

  • If an OVW was incorporated as a learning resource in a MOOC it would not cope

OVWs: coping with variance in load

  • OVWs are synchronous but typical load may be low e.g. less than 5 avatars

  • A high load e.g. more than 50 avatars may be caused by a scheduled event

  • MOOC access would have to be regulated like an art exhibition – by ticket and time

  • Still need to increase the capacity for such scheduled events

  • The Cloud offers pay per use scalability – a good match?

testing scalability: methodology

  • design benchmark

    • calibrate bot and human behaviour

    • establish a close match and use that pattern

  • build testbed and conduct experiments

    • use bots to facilitate exploration of parameter space

  • QoEparameters

    • Frame Time found to be the best measurable discriminator as to load and performance

    • Frames per Second

      • ideally at least the refresh rate of the display device e.g. 60 fps

      • in practice 30 fps or better acceptable

Walk-2 best fit for human behaviour


  • 5 – 100 bots in increments of 5

  • Each bot executes a pattern of behaviour for 10 minutes that matches typical human controlled avatar

  • Each run repeated three times

platforms and virtualisation

  • Cathedral Island

  • Metal:Quad core i7, 8GB

    • Xen: dom0 and domU

    • KVM

    • Virtual Box

  • Amazon ec2 extra large (M1: quad core, 16GB)

frames per second v number of avatars

frame time (ms) vs number of avatars

Comments on the Cloud for OVWs

  • Scaling up is easy once image of OVW is created

    • simply change the underlying AWS machine type

  • Disappointing performance from tests to date, but more powerful machine types are becoming available

  • Still useful to know that for $20 you can run an OVW session for 50 students for 2 hours without owning any server hardware!

Comments on OVW Scalability

  • Number of Concurrent Avatars is only one view of scalability

  • Other approaches include replicating regions and limiting the number of avatars on each replica

    • no longer a single large multi-user interactive environment

    • but, preserves interactive learning resource functionality

  • Fundamentally re-think the architecture e.g. distributed scene graph


  • OVWs and MOOCs complementary educationally

  • OVWs would need to be scheduled with tickets and times if made available as MOOC resources

  • Cloud is potentially good fit for scheduled sessions of known loads

  • Loads can be predicted using benchmark and testbed

  • Current Cloud virtual machines do not scale or perform better than dedicated commodity hardware

  • There are different approaches to OVW scalability

Thank you!

comments and collaborations welcome

Colin Allison

[email protected]

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