A Composability Lexicon

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Spring 2003 Simulation Interoperability
Workshop 03S-SIW-023 A Composability
Lexicon Mikel D. Petty, Ph.D. and Eric W.
Weisel Virginia Modeling, Analysis Simulation
Center Old Dominion University mpetty_at_vmasc.odu.ed
u 757-686-6210
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Acknowledgements ? Project sponsors - Office of
Naval Research gt Harold Hawkins,
Ph.D. - Defense Modeling and Simulation
Office gt Philomena M. Zimmerman Douglas L.
Clark ? Collaborators - ODU/VMASC gt Eric W.
Weisel Roland R. Mielke, Ph.D. - Composability
example assembly gt Katherine S. Petty
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Outline ? Definitions of composability ? Levels
of composability ? Related concepts ? Summary
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Definitions of composability
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Same word, different meanings ? Different
meanings for composability - Found in both
documents and discussion - Experienced at
composability meeting - Noted in review of
literature Petty,2002 - Reported previously
Page,1998
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Selected definitions The ability to rapidly
configure, initialize, and test an exercise by
logically assembling a simulation from a pool of
reusable components. JSIMS,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,1999 The ability to
build new things from existing pieces.
Pratt,1999
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Common definition Composability is the
capability to select and assemble simulation
components in various combinations into
simulation systemsto satisfy specific user
requirements.
Component Repository
Simulation B
1
Simulation A
3
1
2
8
3
3
22
. . .
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N
N
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Defining characteristic of composability ? Compos
itions of simulation components - Composable in
different ways - Suited to different
purposes - Different compositions can be
valid - Combine and recombine
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Levels of composability
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Composability levels ? Different meanings often
differ in level - Level determined
by gt Component being composed gt Composition
that results - Some composability levels in
literature gt Explicitly JSIMS,1997
Page,1998 Petty,2002 Post,2002 gt Implicitl
y U.S. Army,1998 Courtemanche,2002
Henderson,2002 - Levels here a synthesis of
various sources
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Components
Composition
Example
Applications
Events
Unified Endeavor
Federates
Federations
Joint Training Confederation
Packages
Simulations
JSIMS
Parameters
Simulations
JSIMS
Modules
Executables
OneSAF
Models
Composite models
OneSAF
Data
Databases
SEDRIS
Entities
Military units
WARSIM
Behaviors
Composite behaviors
ModSAF
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? Application level - Applications composed into
events - Applications simulations, C4I
systems, networks, auxiliary software - aka
event level Post,2002 ? Federate
level - Federates composed into
federations - Persistent federations, federates
may change - Often supported by interoperability
protocol gt e.g., HLA, DIS, ALSP - aka
federation level Post,2002
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? Package level - Packages composed into
simulations JSIMS,1997 - Packages sets of
models forming consistent subset of battlespace
Page,1998 ? Parameter level - Parameters used
to configure pre-existing simulations - aka
simulation level JSIMS,1997
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? Module level - Software modules composed into
executables - Resulting composition may be
federate or standalone simulation - e.g.,
OneSAF U.S. Army,1998 Courtemanche,2002 ? Mode
l level - Models composed into composite
models - e.g., sub-systems composed into
entities - e.g., OneSAF Henderson,2002 - aka
object level Post,2002 - aka component
level JSIMS,1997
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? Data level - Data sets composed into
databases - e.g., DIS electronic warfare
Wood,1995 - e.g., SEDRIS ? Entity
level - Platforms/entities composed into
military units - May be hierarchical,
multi-leveled - aka federate level Post,2002
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? Behavior level - Behaviors composed into
composite behaviors - Behaviors executed
autonomously by CGF - e.g., FSMs
Calder,1993 - e.g., flow diagrams Peters,2002
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Related concepts
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Interoperability Interoperability is the ability
of different simulations, connected in a
distributed simulation, to meaningfully
collaborate to simulatea common scenario or
virtual world.
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Composability and interoperability ? Composabilit
y interoperability? No. - Interoperability is
necessary but not sufficient for
composability - Composability requires
interoperability - Interoperability possible
without composability, i.e., without ability to
combine and recombine gt e.g., Platform
Proto-Federation Harkrider,1997 gt e.g., MV-22
OPEVAL Federation Huntt,2000
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Syntactic and semantic composability ? Syntactic
composability - aka engineering
composability Pratt,1999 Ceranowicz,2002 -
Implementing composable components - Concerned
with component connectability gt e.g., data
interfaces gt e.g., invocation mechanisms - Can
the components be combined so as to execute
together and exchange data?
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? Semantic composability - aka modeling
composability Pratt,1999 Ceranowicz,2002 -
Ensuring composable models - Concerned with
model compatibility gt e.g., domains of
validity gt e.g., consistent assumptions - Is
the combined computation of the composed models
meaningful? - e.g., subsonic flight dynamics
model composed with supersonic jet engine model
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Semantic composability
Syntactic composability
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? Analogous interoperability types - Syntactic
composability analogous to technical
interoperability - Semantic composability
analogous to substantive interoperability Dah
mann, 1999
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Summary ? Different definitions of
composability ? Composability levels - Component
being composed - Result of composition ? Composab
ility, interoperability different ? Syntactic,
semantic composability different
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End of presentation