Unsupervised Creation of Small World Networks for the Preservation of Digital Objects Charles L. Cartledge Michael L. Nelson Old Dominion University Department of Computer Science Norfolk, Virginia

SP145JCDL Short Paper Presentation2 Order of Presentation Technology enablers Constraints Simple rules for Complex Behavior Simulation approach Simulation results Future work

SP145JCDL Short Paper Presentation3 Motivation Time

SP145JCDL Short Paper Presentation4 Technology Enablers Cost data:

SP145JCDL Short Paper Presentation5 Constraints “ … Tomorrow we could see the National Library of Medicine abolished by Congress, Elsevier dismantled by a corporate raider, the Royal Society declared bankrupt, or the University of Michigan Press destroyed by a meteor. All are highly unlikely, but over a long period of time unlikely events will happen. …” (emphasis CLC) W. Y. Arms, “Preservation of Scientific Serials: Three Current Examples,” Journal of Electronic Publishing, Dec., 1999 Expectancy data: – 101 yrs Picture: Patricia W. and J Douglas Perry Library, Old Dominion University Those that die, do so in avg. 23 yrs – 60 yrs

SP145JCDL Short Paper Presentation6Doctoral Consortium6 Reynolds’s Rules for Flocking Collision Avoidance: avoid collisions with nearby flock mates Velocity Matching: attempt to match velocity with nearby flock mates Flock Centering: attempt to stay close to nearby flock mates Images and rules: My interpretation Namespace collision avoidance Following others to available storage locations Deleting copies of one’s self to provide room for late arrivers

SP145JCDL Short Paper Presentation7 Types of Graphs Small World Shorter Still high (Each graph has 20 vertices and 40 edges.)

SP145JCDL Short Paper Presentation8 Desirable Graph Properties

SP145JCDL Short Paper Presentation9 Unsupervised Small World Graph Creation gamma = 0.0 alpha = 0.99 gamma = 0.7 alpha = <= beta <=0.66 gamma < 0.6 CC is shown as dark lines L is shown as light lines

SP145JCDL Short Paper Presentation10 Phases/Activities Creation (Human or archivist activities) Wandering (Autonomous activities) Connecting (Autonomous activities) Flocking (Autonomous activities)

SP145JCDL Short Paper Presentation11 Creation Any DO

SP145JCDL Short Paper Presentation12 Wandering AB D C Who are you connected to? Connected to: Who are you connected to? Connected to: A Who are you connected to? Connected to: B Who are you connected to? Connected to: A Connected to: B, C Who are you connected to? Connected to: A Who are you connected to?

SP145JCDL Short Paper Presentation13 Connecting AB D C Possible connection Connection NOT established Possible connection Connection established

SP145JCDL Short Paper Presentation14 Flocking A’A’’ AB D C A’ A’’ C’ C’’ D’ D’’

SP145JCDL Short Paper Presentation15 Typical Simulation Parameters alpha = 0.5 beta = 0.6 gamma = 0.1 Number of DOs = 1000 Number of hosts = 1000 Min number desired replicas = 3 Max number desired replicas = 10 Max number of replicas per host = 20

SP145JCDL Short Paper Presentation16 Simulation Results and Analysis

Future work Test the autonomous graphs for resilience to error and attack Test what happens when a graph becomes disconnected Test what happens when a disconnected graph becomes re-connected SP145JCDL Short Paper Presentation17

SP145JCDL Short Paper Presentation18 Conclusions We have shown that Digital Objects can autonomously create small world graphs based on locally gleaned data These graphs can be used for long term preservation We intend to study these graphs focusing on their tolerance to isolated and widespread failures

SP145JCDL Short Paper Presentation19 And that concludes my presentation.

SP145JCDL Short Paper Presentation20 Backup Information Equations for Average Path Length and Clustering Coefficients