1. Resilience through Dynamic Reconfigurations in Agent Systems Ilya Lopatkin Newcastle University, School of Computing Science

2. Multi-Agent System (MAS)‏ Agent Resource 2 Active agents Resources Communication

3. Multi-Agent System (MAS)‏ Agent 3 Active agents Passive agents Communication Agent

4. Threats and reconfiguration in MAS Questions concerned:  how to find appropriate components to use after failures?  which of them to choose? 4 Agent  Agent is unavailable  Abnormal behaviour  Disconnection  Inadequate quality of data  Inadequate QoS  Lack of required characteristics ? ? ? ? ? ?

5. Search mechanism The place of the search mechanism in FT 5 Damage confinement and assessment Error recovery Fault treatment and continued service Error detection * T. Anderson, P. A. Lee. Fault Tolerance: Principles and Practice. Prentice Hall, London, 1981

6. Scope of work 6 Searcher Criteria  Location addresses  Request List of locations Error detection Search Reconfiguration

7. Device Platform Location Agent Middleware Agent Middleware Agent Middleware CAMA abstractions 7

8. Agent Evaluation of locations Location Value* Searcher 8 evaluates produces * G. Di Marzo Serugendo, J. Fitzgerald, A. Romanovsky, and N. Guelfi. A Metadata-Based Architectural Model for Dynamically Resilient Systems. In 22nd ACM Symposium on Applied Computing, Seoul, Korea, March 11- 15, 2007. pp 566-573. ACM, 2007.

9. Sharing values among agents Location 1 Location 2 Value A2 Agent B Agent A Criterion Value A2 9 uses reads from saves to evaluates uses

10. Aggregating values Location 1 Location 2 Value Q2 Value P2 Agent A Value PQ2 contains Location 3 10 saves PQ2 contains reads Q2 reads P2 aggregates into

11. Criteria Application-specific Evaluate, aggregate, and compare values May include any resilience criterion Examples: Availability. Value: estimated time per week/month/year Connection properties, latency. Value: average time in ms Number of failures. Value: integer Quality of service. Value: some complex structure 11

12. Threats and reconfiguration in MAS Questions concerned:  how to find appropriate components to use after failures?  which of them to choose? 12 Agent  Agent is unavailable  Abnormal behaviour  Disconnection  Inadequate quality of data  Inadequate quality of service  Lack of required characteristics ? ? ? ? ? ? meta-data

13. Advantages Works for any type of components Leads to Any resilience criteria Autonomous agents High scalability 13

14. Problems First wave of agents Too many locations Lack of values Different treatment of the same values Need for a general ontology to represent values Hidden stigmergy may lead to unpredictable behaviour 14

15. Thank you!