Supporting Simulations on the Cloud using Workflows & Virtual Machines Gary Polhill Macaulay Land Use Research Institute Edoardo Pignotti Computing Science, University of Aberdeen

Overview  The SwarmCloud project  Social simulation & the Cloud  A virtualised simulation environment  Facilitating access with workflows  Workflows on the Grid/Cloud  Conclusions

The SwarmCloud Project  Goal: to enable the FEARLUS simulation model to be run on National Grid Service infrastructure  What’s so hard about that?  FEARLUS is written in Obj-C for the Swarm libraries— notoriously difficult to install  Numbers of pre-requisite libraries  Can be sensitive to particular versions of libraries and Unix commands  Typical Grid use-cases involve running a script  e.g. Model calibration  Other software environments for social simulation exhibit the same issues (barrier to adoption)

How can social simulation benefit from the Cloud?  Enabling large-scale distributed simulations  e.g. Fraser et al. (2009 Science), Birkin et al. (2009 SSCoRe), Tang & Bennett (2009 US-IALE)  More challenging because of managing agent interactions across node boundaries  Enabling multiple runs of smaller-scale models for:  Exploring parameter space  Experimenting with algorithmic variants  Trying different scenarios  Increasing sensitivity (more runs with different seeds)  ‘Embarrassingly Parallel’

Software dependencies  Swarm software dependencies shown  ‘worst-case’  Java not immune  Pre-requisite jars can be required (with version sensitivity)  JRE version sensitivity  Obvious problems for programs/libraries using JNI

The solution: A virtualised simulation environment: simulationBox  We used a lightweight version of Centos 5.2 to create a virtualised simulation environment containing Swarm, MASON and RePast  Compressed image ~1GB in size   The simulation environment was created using Sun’s VirtualBox virtualisation software  Binaries available under a Personal Use and Evaluation Licence 

Virtualisation on the Cloud  The virtualisation approach relies on the Cloud host making virtualisation facilities available  The National Grid Service is testing a virtualisation service based on Xen/EUCALYPTUS at Oxford  Xen: Open Source standard for virtualisation   EUCALYPTUS (Elastic Utility Computing Architecture Linking Your Programs To Useful Systems): Open-source system for implementing clouds  Provides an authentication layer, and manages virtual machines using ec2 tools 

Facilitating access: Workflows  Virtualisation provides a replicable environment for compiling and running a social simulation  ‘User interface’ not very friendly  Access via ssh  Kepler workflow tool used to design simulation experiments

Upper Deeside Case-study

Workflows on the CLOUD  We have developed a number of Kepler workflow activities based on the ec2 tools:  Authenticate a user on the Cloud  Upload simulationBox to a node manager  Create instances of simulationBox on the Cloud  Query for available simulationBox instances on the Cloud  Compile a new simulation model on a simulationBox instance  Run the model multiple time across different VM instances  Collect and analyse results, saving them on the local machine  Our Kepler libraries can be downloaded from

Compile a simulation model

Run an experiment

Conclusions  For Cloud infrastructure supplying virtualisation services it is possible to run social simulations with specific computing requirements  Access is facilitated through workflows that can be shared amongst people  Website:  ESSA 2009 Tutorial on simulationBox  Large Scale Social Simulation Special Interest Group (ESSA)  SwarmFest 2010