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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

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?

S tructure of this talk
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
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 e ducation example

STEM education example

Internet Routing Protocols

Internet routing
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
Fife and Tayside regional network

RNEP: Regional Network Entry Point

POP: Point of Presence

Link from rnep1 to abertay is broken interactively by student
Link from RNEP1 to Abertay is broken (interactively by student)

after watchable protocol exchanges the forwarding table for RNEP1 changes

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

K 4 visualisation gets tricky in 2d
k=4: visualisation gets tricky in 2D

H ypercube k 4
hypercube k=4

R outing island complements other learning resources
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

Popular youtube video of djikstra s algorithm
popular youtube video of djikstra’s algorithm

Kurose ross fig 4 27
Kurose & Ross Fig. 4.27

Unesco 2012
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
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
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
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
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: 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
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


  • 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

P latforms and virtualisation
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
frames per second v number of avatars

Frame time ms vs number of avatars
frame time (ms) vs number of avatars

Comments on the cloud for ovws
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
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
Thank you!

comments and collaborations welcome

Colin Allison

[email protected]