Resilience through Dynamic Reconfigurations in Agent Systems Ilya

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

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

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

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

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

Scope of work Error detection Search Location addresses ØRequest Reconfiguration List of locations Ø Searcher Criteria 6

CAMA abstractions Agent Middleware Location Agent Middleware Platform Device 7

Evaluation of locations Agent evaluates Location Searcher produces Value* * G. Di Marzo Serugendo, J. Fitzgerald, A. Romanovsky, and N. Guelfi. A Metadata-Based Architectural Model for Dynamically Resilient Systems. In 22 nd ACM Symposium on Applied Computing, Seoul, Korea, March 1115, 2007. pp 566 -573. ACM, 2007. 8

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

Aggregating values Value PQ 2 Location 1 aggregates into contains Value Q 2 reads Q 2 saves PQ 2 Agent A Location 2 reads P 2 Location 3 contains Value P 2 10

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

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

Advantages Works for any type of components Leads to <reconfiguration type you've just remembered> Any resilience criteria Autonomous agents High scalability 13

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

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