A Simulator for Social Exchanges and Collaborations - Architecture and Case Study

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Social collaboration scenarios, such as
sharing resources between friends, are becoming increasingly prevalent in recent years. An example of this new paradigm is Social Cloud Computing, which aims at leveraging existing digital relationships within social networks for the exchange of resources among users and user communities. Due to their complexity, such platforms and systems have to be carefully designed and engineered to suit their purpose. In this paper, we propose a general-purpose simulation tool to help in the design and analysis of Social Collaboration Platforms, and discuss potential use cases and the architecture of the simulator. To show the usefulness of the simulator, we present a simple use case in which we study the effects of an incentive scheme on the system and its user community.

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A Simulator for Social Exchanges and Collaborations - Architecture and Case Study

  1. 1. A Simulator for Social Exchanges and Collaborations ‐Architecture and Case StudyeScience 2012, ChicagoChristian Haas, Simon Caton, Daniel Trumpp, Christof WeinhardtKARLSRUHE SERVICE RESEARCH INSTITUTE (KSRI) Social Collaboration Simulator Monitoring User  Incentive  Experiment  SmallWorldNetwork ... Application Sensor Applications Scheme Controller Exchange  Exchange Sensor Mechanism Currency Artifact ... Mechanisms Runtime User Sensor Core  User Resource Relationship TrustContext Elements Resource SensorKIT – University of the State of Baden-Württemberg andNational Research Center of the Helmholtz Association www.kit.edu
  2. 2. Motivation: Study of Complex Social Systems Collaboration Platform How can we study collaboration and cooperation in complex social systems? Theory Simulation Empirical Studies2 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  3. 3. Agenda 1 Purpose and Applications of the Simulator 2 Architecture and Implementation 3 Case Study3 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  4. 4. A Simulation Tool for Complex Social Systems Purpose of the Simulation Tool Platform design: Analysis of different architectures, schemes, settings, policies, ... Prediction: Study effects of changes in system rules on the platform Components  Network  Users  Objective  Characteristics  Resources  Platform Goal4 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  5. 5. Potential Applications of the Simulation Tool Network Structure User Types Random vs. Small‐World structures Utility function distributions Selfish Provisioning Leontief Convex Perfect Substitutes Sample  Consumption Applications Effect of incentives on  Selection of collaboration  collaboration activities intensity Learning Behavior User Strategies Incentive Schemes5 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  6. 6. Architecture: Overview of Simulator Structure Social Collaboration Simulator Monitoring User  Incentive  Experiment Applications SmallWorldNetwork … Application Sensor Scheme Controller Exchange Mechanisms Mechanism Currency Artifact … Exchange Sensor Runtime User Sensor Core  User Resource Relationship TrustContext Elements Resource Sensor  Hierarchical layered structure with interchangeable components Design  Component functionality specified in interfaces (API) Principles  Scenarios and use cases are specified on the highest level6 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  7. 7. Scenario: Resource sharing between connected users Setting  Users connected based on  social network  Users request and provide  (computational) resources  (similar to BOINC)  Requests advertised to  other users Observations from similar systems: Users are heterogeneous (availability, sharing behavior,…) Active contribution of users is vital for the system Percentage of ‘free‐riders’ can be significant1 Focus: Contribution scheme to increase user participation 1: See Adar 20007 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  8. 8. Contribution Scheme Goals Main idea1: Trading Constraint Increase active participation, i.e.  Each user i has a contribution score strengthen resource provisioning User i can request resources from user j Restrict ‘free riding’‐ behavior iff 1: Adapted from Ranganathan et al. 2004 Contribution Score κ ,κ : Quantity Scarcity How scarce is the provided resource,  How many resources did the user  defined by the ratio demand vs.  provide? supply? 8 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  9. 9. Modelling the Users Modeled through a Utility Function Selfish Provisioning Consuming      vs Provisioning  Leontief Behavior and  (‘selfish’) (‘reciprocal/altruistic’) Utility Types Perfect Convex Substitutes 6 types with different utility types2: Consumption (weak) selfish (weak) Leontief (weak) perfect substitutes 2: based on Andreoni et al. 2002 s12 Trust s21 Trust score influences matching of offers with requests9 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  10. 10. Evaluation(1) Effect on Utility What is the effect of the contribution scheme on the average utility of users? 1.2 1 Average Utility per User 0.8 0.6 NoTradingConstraint TradingConstraint 0.4 0.2 0 20 50 100 200 500 Network Size Total system‐wide utility decreases Contribution scheme decreases set of potential sharing partners10 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  11. 11. Evaluation (2) Effect on User Types To what degree are different user types affected by the contribution  scheme? 1.2 Relative Utility compared to No Trading 1 Type 1: Selfish 0.8 Type 2: Weak Selfish Constraint 0.6 Type 3: Leontief Type 4: Weak Leontief 0.4 Type 5: Perfect Substitutes 0.2 Type 6: Weak Perfect 0 Substitutes 20 50 100 200 500 Network Size Selfish users incur highest utility loss  Contribution scheme punishes ‘free‐riders’ Relative utility loss of other user types is low11 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  12. 12. Steps towards Simulator Calibration Study the effect of a Scenario contribution scheme on users Model collaboration system Approach Model user behavior User types differently affected by Results contribution scheme Application Type Distributions to new Network Structures scenarios …12 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  13. 13. Conclusion Summary  Simulation tool for social  collaboration  Layered architecture with  interchangeable components   Case study to show usefulness of  such a simulator Future Work  New functionality (new mechanisms, network structures,…)  Further case studies   Provide as open‐source Re‐* tool13 12.10.2012 Christian Haas – A Simulator for Social Exchanges and Collaborations - Karlsruhe Service Research Institute Architecture and Case Study www.ksri.kit.edu
  14. 14. ThanksChristian Haas: ch.haas@kit.edu http://www.ksri.kit.edu/SocialCloud http://www.facebook.com/SocialCloudComputingKARLSRUHE SERVICE RESEARCH INSTITUTE (KSRI) Social Collaboration Simulator Monitoring User  Incentive  Experiment  SmallWorldNetwork ... Application Sensor Applications Scheme Controller Exchange  Exchange Sensor Mechanism Currency Artifact ... Mechanisms Runtime User Sensor Core  User Resource Relationship TrustContext Elements Resource SensorKIT – University of the State of Baden-Württemberg andNational Research Center of the Helmholtz Association www.kit.edu

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