ASSL Autonomic System Specification Language

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DEPARTMENT OF COMPUTER SCIENCE AND SOFTWARE
ENGINEERING CONCORDIA UNIVERSITY Montreal, Qc,
Canada
ASSL Autonomic System Specification Language
by Emil Vassev
March 11, 2008
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Outline
Index

• Problem Statement
• Autonomic Computing
• ASSL Framework
• Conclusion

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Introduction
Problem Statement

• Moores Law
• Over 40 years IT obeys Moors Law increasing
  exponentially the complexity and power of the
  contemporary hardware.
• Software
• New hardware requires new software - no longer
  constrained by hardware space and speed, has
  grown up to over millions of lines of code.
• Parallel with Moore's Law?
• So we have increased the size and complexity of
  software even faster than Moores Law. In fact,
  this is why there is a market for faster
  processors - software people have always consumed
  new capability as fast as or faster than the chip
  people could make it available.
• Nathan Myhrvold - a former chief technology
  officer at Microsoft

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Introduction
Problem Statement

• Current Situation
• Tremendous increase of application complexity
• Service-Oriented architecture running on grids.
• Multi-core CPUs, integrated communication and
  management.
• Solution
• Self-adaptive and autonomic computing (AC)
  systems.
• Problem
• Crucial need of programming techniques and
  technologies
• imply AC principles
• provide us with programming concepts for
  implementing autonomic systems (AS).

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Background
Autonomic Computing State of the Art

• Four basic self-managing objectives
• self-configuration
• self-optimization
• self-healing
• self-protection.
• Requirements
• self-aware - aware of its internal state
• self-situated - an AC system monitors its
  environment (external knowledge)
• self-monitoring - an AC system monitors its
  internal components (internal knowledge)
• self-adjusting - able to adapt to the changes
  that may occur.

Self-Configuration. The AS readjusts itself
automatically, either to support a change in
circumstances or to assist in meeting other
system objectives. The self-configuration is
according to high-level objectives.
Self-Optimization. The AS measures its current
performance against the known optimum and has
defined policies for attempting improvements. It
can also react to the users policy changes
within the system.
Self-Healing. In reactive mode, the AS must
effectively recover when a fault occurs, identify
the fault, and, when possible, repair it. In
proactive mode, the AS monitors vital signs to
predict and avoid health problems.
Self-Protection. The AS defends itself from
accidental or malicious external attacks, which
requires awareness of potential threats and the
means to manage them.
ANS through self-regulation controls and monitors
the human body.
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Background
Autonomic Computing Autonomic Element (AE)

• AE - the core of an AS.
• AE - a self-aware component able to manage its
  own behavior.
• Control loop
• the core of an AE.
• a set of functionally related and sharing
  knowledge units monitor, analyzer, planner, and
  executor.

Managed resource (highly scalable)
AE Generic Architecture IBM Blueprint
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Background
Autonomic Computing - A Means for Complexity
Reduction

• ASs aim to reduce complexity of the IT
  infrastructure by providing self-managing
  components.
• AC helps to reduce the total cost of ownership of
  IT systems.
• Problem
• How to achieve the AC properties, i.e. how to
  build autonomic systems.
• Complexity paradox - AC reduces the complexity
  for the final user, but the design and
  implementation of ASs become more complex.
• AC introduces additional layer to the
  architecture of the system under consideration.
• Solution
• Complexity reduction by hiding complexity via
  abstraction.

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ASSL Framework
ASSL Multi-Tier Specification Model

• Rationale
• scalable specification model
• provides judicious selection and configuration of
  infrastructure elements and mechanisms for ASs
• decomposes an AS in two directions 1) into
  levels of functional abstraction 2) into
  functionally related sub-tiers
• presents the system from three different
  perspectives 1) AS 2) ASIP 3) AE
• matches the AS builders needs
• flexible approach to specification.

• AS Development
• Helps to design and generate an AC wrapper that
  embeds the components of existing systems, i.e.
  it allows a non-intrusive adding of
  self-management features to existing systems.
• Allows a top-down development approach to ASs,
  where the generated framework instance will guide
  the designers to the needed components and their
  interfaces of the system under consideration.

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ASSL Framework
ASSL Tiers

• AS/AE SLO Service-level objectives (SLO) - a
  higher-level form of behavioral specification
  that establishes objectives (performance).
• AS/AE Self-Management Policies - the four AC
  self-management policies (the so-called
  self-CHOP) self-configuring, self-healing,
  self-optimizing, and self-protecting.
• ASSL specifies the policies with fluents
  (conditions with a timed duration) and mappings,
  which use actions and events.
• ASSL allows specification of policies that cannot
  be classified as self-CHOP.

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ASSL Framework
ASSL Tiers

• ASIP/AEIP - The ASSL framework implies two
  communication protocols - public (ASIP) and
  private (AEIP). The autonomic element interaction
  protocol (AEIP) uses the same specification
  constructs as ASIP does. Two AEs exchange
  messages over their AEIP only if they have an
  agreement on it.
• AS/AE Actions - routines that can be performed in
  response to a self-management policy, SLO, or a
  behavior model.
• AS/AE Events - used to specify many of the ASSL
  structures, such as fluents, self-management
  policies, actions etc.

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ASSL Framework
ASSL Tiers

• AS/AE Metrics - constitute a set of parameters
  and observables, which the autonomic elements can
  control.
• AS Architecture - specifies the topology of the
  AS (autonomic system).
• Managed Resource Interface interface to control
  the managed resource.

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ASSL Framework
ASSL Toolset Editor, Parser, Consistency
Checker, Code Generator
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ASSL Framework
Java Code Generation
Gener. Rules
ASSL Spec
Code Generator
ASSL Tokens
ASSL Scanner
ASSL Pre-parser
ASSL Tokens
Consistency Checker
ASSL Grammar Parser
ASSL Parser
DFA, First Follow Sets
ASSL Grammar
Cons. Rules
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ASSL Framework
AE Architecture for ASSL
ASSL generates the AS skeleton. AEs will be
generated as following
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ASSL in Action
Specifying ANTS with ASSL
NASA is currently investigating
biologically-inspired swarm technologies for the
development of autonomous prospective exploration
missions. Autonomous Nano-Technology Swarm
(ANTS) concept mission is a novel approach to
asteroid belt resource exploration.

• Classes of spacecraft
• Rulers
• Messengers
• Workers.

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ASSL in Action
Specifying ANTS with ASSL Self-Configuring
Team formation on the fly to explore asteroids.

• Self-configuring spec
• SELF_CONFIGURING
• - fluents
• - mappings.
• actions
• events
• metrics.

A fluent has a timed duration, for example a
state like there is a lack of idle x-ray
workers.
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ASSL in Action
Specifying ANTS with ASSL Safety SLO

• Goal ANTS safety objectives should present a
  level of safety that at least makes ANTS capable
  of operating under the following hazards
• a collision with the other spacecraft units or
  asteroids
• high-density magnetic fields
• high radiation (due to a solar eruption)
• a high energy level (due to a solar eruption)
• a loss of communication among the ANTS AEs.

NASA Risk Index Determination
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Conclusion

• ASSL is a specification language for specifying
  autonomic systems.
• ASSL is designed as a framework and provides a
  multi-tier specification model.
• ASSL allows expressing autonomic systems, as a
  set of interacting AEs, at three main levels
  the AS level, the AS interaction protocol level,
  and the AE level.
• TODO Consistency Checker Code Generator.
• Future work model checker.

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Thank you!