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Presented by:
Tiina Niklander

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Eight Goals for a System
1. System must know itself
2. System must be able to reconfigure itseld within its
operational environment
3. System must pre-emptively optimise itself
4. System must detect and respond to its own faults as
they develop
5. System must detect and respond to intrusions and
attacks
6. System must know its context of use
7. System must live in an open world
8. System must actively shrink the gap between
user/business goals and IT solutions
16.1.2007 6
Autonomic Computing
• Basic model: closed
control loops
– Based on Process
Control Theory
• Controller
continuously
compares the actual
and expected
behavior and makes
needed adjustments
Controller
Controlled
object
measurement adjustment
model
SEE: Any control-theory books
16.1.2007 7
Autonomic Control Loop
Collect
Act
Decide
Analyse
Use uncertain reasoning
Policies, rules, …
Collate, combine,
Find trends, correlations
Modify behavior,
Inform users,
From system elements,
Users, environment, agents, …
16.1.2007 8
Elements of Self-Healing 1/2
Fault Detection
Degradation
Fault response
Fault recovery
Time constants
Assurance
System response
Fault duration
Fault manifestation
Fault source
Granularity
Fault profile expectations
Fault model
Philip Koopman: Elements of the Self-Healing System
Problem Space. In Proceedings of ICSE WADS 03.
16.1.2007 9
Fault models
• Each aspects describes a characteristic of
the fault.
– Duration: Is the fault permanent?
– Manifestation: What does the fault do to the
system?
– Source: Where does the fault come from?
– Granularity: Is the fault global or local?
– Occurrence expectation: How often will the
fault occur?
16.1.2007 10
System Response
• Each aspect describes a characteristic of reacting
to faults.
– Detection: How does a system detect faults?
– Degradation: Will the system tolerate running in a
degraded state?
– Response: What does a system do when the fault
occurs?
– Recovery: Once a fault occurs, can the system return to
a healthy state?
– Time: How much time does the the system have to
respond to a fault?
– Assurance: What assurances does a system have to
maintain while handling a fault?

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for more details, please visit
http://cs.helsinki.fi/u/niklande/opetus/...-intro.pdf

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