Computational Complexity of Selection Components for Composition

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Spring 2004 Simulation Interoperability
Workshop 04S-SIW-105 A Survey of Engineering
Approaches to Composability Eric W. Weisel,
Ph.D. 1, Mikel D. Petty, Ph.D.2, and Roland R.
Mielke, Ph.D.2 1WernerAnderson, Inc. 2Virginia
Modeling, Analysis Simulation Center Old
Dominion University
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Acknowledgements ? Sponsors - Office of Naval
Research gt Affordable Human Behavior
Modeling gt Harold Hawkins, Ph.D. - Defense
Modeling and Simulation Office gt Composable
Mission Space Environments gt Philomena M.
Zimmerman Douglas L. Clark
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Composability concepts and lexicon ? Definition
of composability ? Levels of composability ? Typ
es of composability
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Definition of composability Composability has
been defined a number of ways The ability to
rapidly configure, initialize, and test an
exercise by logically assembling a simulation
from a pool of reusable components (JSIMS
Composability Task Force, 1997). The ability to
create, configure, initialize, test, and validate
an exercise by logically assembling a unique
simulation execution from a pool of reusable
system components in order to meet a specific set
of objectives (Harkrider and Lunceford,
1999). The ability to build new things from
existing pieces (Pratt, Ragusa, and von der
Lippe, 1999). The ability to compose
models/modules across a variety of application
domains, levels of resolution and time scales
(Kasputis and Ng, 2000). Composability means
that a highly customized simulation can be
created from a pool of reusable elements (Aronson
and Wade, 2000). Composability is the capability
to select and assemble simulation components in
various combinations into valid simulation
systems to satisfy specific user requirements
(Petty and Weisel, 2003b).
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Definition of composability Composability is the
capability to select and assemble components in
various combinations into simulation systems to
satisfy specific user requirements.
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Levels of composability Application.
Applications such as simulations, real C4I
systems, networks, communications equipment, and
auxiliary software components are composed into
simulation events, exercises or
experiments. Federate. Simulations are composed
into network-connected distributed simulation
systems that exchange data at run-time. Package.
Pre-assembled packages comprising sets of models
that form a consistent subset of the battle space
are composed into simulations. Parameter.
Parameters are used to configure pre-existing
simulations.
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Levels of composability Module. Software
modules are composed into software
executables. Model. Separate models of
smaller-scale processes or objects are composed
into composite models of larger-scale processes
or objects. Data. Sets of data are composed into
databases. Entity. Platforms/entities, typically
data, rather than with software, are composed
into groupings such as military units, force
structures, and scenario orders of
battle. Behavior. Low-level atomic behaviors are
composed into high-level composite behaviors,
which are to be executed by autonomous simulation
entities in a computer generated forces system or
constructive simulation.
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Levels of composability
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Levels of composability
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Two types of composability ? Syntactic
(engineering) composability - Implementing
composable components - Concerned with component
connectability gt e.g., data interfaces,
invocation mechanisms - Can the components be
combined? ? Semantic (modeling)
composability - Ensuring composable
models - Concerned with model compatibility gt e
.g., domains of validity, consistent
assumptions - Is the composition of models
meaningful?
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Related ideas ? Interoperability is the ability
of different simulations, connected in a
distributed simulation system, to meaningfully
collaborate to simulate a common scenario or
virtual world. ? Integration is the process of
configuring and modifying a set of components to
make them interoperable and possibly
composable. ? Configurability is the ability to
include varying numbers of identical federates in
a federation.
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Semantic composability
Syntactic composability
Same components, different semantics
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Engineering approaches to composability Most
composability research and development to date
has been aimed at developing concepts,
technologies, tools, protocols, standards,
control mechanisms, interfaces, and processes to
enable the rapid, efficient, and flexible
assembly of simulation systems from components in
a practical setting.
Approaches different than levels
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Five approaches identified ? Common
library ? Product line ? Interoperability
protocol ? Object model ? Formal
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• Common library
• Common library. The common library approach
  depends upon an organizing framework for a
  library of reusable software modules.
• Open architecture
• Simulation development system
• Tools, services, standards, and interfaces
• Joint Modeling and Simulation System (JMASS)

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• Product line
• Product line. The product line approach provides
  a contained simulation development system
  utilizing layers of products for development of
  specific simulation systems.
• Simulation development system
• Simulation development products
• One Semi-automated Forces (OneSAF)

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• Interoperability protocol
• Interoperability protocol. The interoperability
  protocol approach is based on the run-time
  exchange of simulation data or services,
  typically using an interoperability protocol such
  as DIS, ALSP, or HLA.
• Open architecture
• Standard interoperability protocol
• Joint Simulation System (JSIMS)
• Combat Trauma Patient Simulator (CTPS)
• Combined Arms Tactical Trainer (CATT)
• Close Combat Tactical Trainer (CCTT)

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• Object model
• Object model. The object model approach depends
  upon a standard for model specification.
• Open architecture
• Well-defined model specification
• Base Object Model (BOM)

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Formal The formal approach depends upon a
simulation formalism to define composability in a
theoretic or mathematical way. DEVS-based
systems Semantic composability theory The
formal approach is unique in its attempt to prove
in a formal or mathematical way how models can be
composed.
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Engineering approaches to composability
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Engineering approaches to composability
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End of presentation