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

2. Metaverse to MOOC:Scaling Virtual Worlds inthe Cloud? C.J. Davies Colin Allison Iain Oliver John McCaffery Alan Miller

3. motivation • 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?

4. 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

5. 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

6. STEM education example Internet Routing Protocols

7. 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

8. Fife and Tayside regional network RNEP: Regional Network Entry Point POP: Point of Presence

10. Link from RNEP1 to Abertay is broken (interactively by student) after watchable protocol exchanges the forwarding table for RNEP1 changes

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

12. k=4: visualisation gets tricky in 2D http://blogs.cs.st-andrews.ac.uk/openvirtualworlds

13. hypercube k=4 http://www.cs.berkeley.edu/~demmel/cs267-1995/lecture11/Hypercube4D.gif

14. k=4: 3D virtual world visualisation

15. 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

16. document centre

17. popular youtube video of djikstra’s algorithm

18. OSPF example from Peterson and Davie

19. Kurose & Ross Fig. 4.27

20. What is meant by “Open” ?

21. 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.”

22. 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

23. 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

24. 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

25. 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

26. 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?

27. 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

28. Walk-2 best fit for human behaviour

29. tests • 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

30. 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)

31. frames per second v number of avatars http://blogs.cs.st-andrews.ac.uk/openvirtualworlds

32. frame time (ms) vs number of avatars http://blogs.cs.st-andrews.ac.uk/openvirtualworlds

33. 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!

34. 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

35. Conclusions • 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

36. Thank you! comments and collaborations welcome Colin Allison ca@st-andrews.ac.uk