Resilience through Dynamic
Reconfigurations in Agent Systems
Ilya Lopatkin
Newcastle University, School of Computing Science
Multi-Agent System (MAS)
Resource
Active agents
Resources
Agent
Agent
Communication
Agent
Agent
Resource
2
Multi-Agent System (MAS)
Agent
Active agents
Passive agents
Agent
Agent
Communication
Agent
Agent
Agent
3
Threats and reconfiguration in MAS






Agent is unavailable
Abnormal behaviour
Disconnection
Inadequate quality of data
Inadequate QoS
Lack of required characteristics
Agent
?
Agent
Agent
?
?
Agent
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
Request

Reconfiguration
List of locations
Searcher
Criteria
6
CAMA abstractions
Agent
Middleware
Agent
Middleware
Location
Agent
Middleware
Platform
Platform
Device
Device
7
Evaluation of locations
Agent
Location
evaluates
Searcher
produces
Value*
* 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 1115, 2007. pp 566-573. ACM, 2007.
8
Sharing values among agents
Criterion
uses
uses
Agent B
uses
Value
A2
Agent A
reads from
Location 1
saves to
evaluates
Location 2
Value
A2
9
Aggregating values
Value
PQ2
Location 1
contains
Value
Q2
aggregates into
reads Q2
saves PQ2
Agent A
Location 2
reads P2
Location 3
contains
Value
P2
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
Agent
?
?
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
Thank you!