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avionics can effectively prolong the
life of an aircraft, potentially doubling its
length of service. Through continuous
research and development investment,
the Smiths Aerospace manufacturing
facility at Bishops Cleeve, near Cheltenham
in the UK, incorporates the latest
technologies into leading-edge avionic
display products, mission management,
and power-switching systems.
In the late 1990s, the Smiths software
development teams at Cheltenham produced
a standard approach to the analysis
and design of software. Structured analysis
techniques were used to provide a functional
breakdown of the requirements
placed on the software. However, in place
of the structured design techniques traditionally
used, the company had adopted an
Object Oriented (OO) design approach.
This technique was seen to offer significant
advantages over structured, top down
SUCCESS STORY: UML
Smiths Aerospace
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Tools Used:
Kennedy Carter’s iCCG, UML™, iUML™,
Model Driven Architecture™ (MDA™)
Description:
Lockheed Martin Aeronautics at Fort Worth,
Texas has used the OMG’s Model Driven
Architecture to develop the F-16 Modular
Mission Computer (MMC) Application
Software. Their goal was to achieve crossplatform
compatibility and increased
productivity and quality, all in the context
of the demanding environment of avionics
software development.
Problem:
The F-16 MMC team originally used traditional
CASE tools with an OO modeling
notation to specify the software before
manually coding in Ada. When they
migrated their development to Kennedy
Carter’s iUML tool, they gained the ability
to use a UML action language which made
their UML models executable. They could
then test their UML models to verify their
intended behavior before hand-coding
the implementation.
More recently they have used Kennedy
Carter’s iCCG product to specify, in
eXecutable UML, an Ada code generator
which can automatically generate 100%
of the Ada implementation.
By this means they guarantee that their
UML models are entirely platform independent
and portable across any future
platform.
In Lockheed Martin’s case, what constitutes
the platform?
The software execution platform effectively
raises the abstraction level of the
hardware to provide a platform on which
code generated from eXecutable UML
models can run directly. Lockheed Martin’s
goal of complete cross-platform compatibility
implies a very strong form of platform
independence whereby the UML models
which specify the Application software
behavior can be ported without change,
even if the Application Software Interface
changes.
Solution:
The use of MDA allows the mission
software functionality to be formalized as
eXecutable UML models (xUML); such
models are Platform Independent Models
(PIM) in MDA. Platform independence is
essential if the goal of decoupling the
models from any changes to the Software
Execution Platform is to be achieved.We
use the term xMDA to mean an MDA
approach augmented by the use of
xUML. xUML models are expressed using
a UML action language based on the
newly adopted precise action semantics
for the UML (see http://www.omg.org/
technology/documents/modeling_spec_c
atalog.htm#Action_Semantics).
Executable models support the MDA
approach in two main ways. First, they
allow early testing using simulation and
debugging tools. Secondly, since they are
a full and formal specification of the system
behavior, they allow generation of the
target code. Defining a mapping from
the rigorously defined PIM (expressed in
xUML) to the implementation, is what is at
the heart of xMDA. Since xUML models
are executable and rigorous they act as
much more than a simple visual agenda
for the software developers, they actually
embody all the business logic required to
execute and verify the system.
Definition of the Platform Independent
Model (PIM) to Platform Specific
Model (PSM) Mapping:
The basis of defining a mapping that
allows full and automatic translation of the
PIM models, expressed in xUML into the
implementation is to build an xUML model
of the translation system itself and execute
it! The elegant conceptual coherence of
employing xUML both in the businessmodeling
realm and in building the translator
means that a minimum set of new
　
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