Transcript A New Philosophy for STEP Implementation

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A New Philosophy for STEP
Implementation
- STEP for the Web (S4W)
David Price
October 2003
All Presentation Material Copyright Eurostep Group AB
STEP for Web philosophy, not religion
• There is a *philosophy underlying this discussion
– SC4 made a first foray into “the Web” and replaced
EXPRESS/P21 with DTD/XML
• We got free tools and a bigger pool of programmers
• However, lots of other new capabilities were missed because
SC4 cares about the “pretty-ness” of the XML (and still does)
– The new S4W philosophy says… SC4 has been missing
the forest for the trees
• What is important is what new capabilities the XML enables
*Caveat : This philosophy doesn’t do calculus, so it’s not to be
applied everywhere
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The new S4W philosophy
• SC4 should focus on putting the semantics of its
schemas/data into the forms new Web capabilities
use
– Practically speaking, this means others control the XML
– However, by giving up control, implementors gain the
use of new toolkits and capabilities
– This may also result in several XML representations of
the same schema/data… but that’s OK! Each has a
purpose.
– So, under this philosophy the verbose OWL syntax is
far superior to any Part 28 configuration
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Part 25, UML and exff
• Part 25 fits under this philosophy
• Translating EXPRESS to UML means implementors
can use powerful software engineering systems
– Lowers the cost of STEP implementation
– Enables use of languages SC4 standards don’t support
(e.g. Ada, Smalltalk, OWL)
– We benefit by giving up some level of control
• In support of this philosophy, Eurostep has
started an open-source project called “exPRESS
for free”
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exff Problem Statement
•
While it's true that
– STEP and EXPRESS have been in-work 10-15 years or
more, and
– STEP has saved organizations time and money
•
It's also true that
– STEP and EXPRESS have not "taken off" the way UML
and XML have in recent years
– In many ways, STEP was ahead of its time
– As things stand today, there are many good STEP
models that will not be widely used
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exff Architecture
Software development tools
EXPRESS
IDE
Engineering application
UML
application code,
database, web service,
knowledge base, …
EXPRESS
XML
exff
XMI
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exff Architecture Details
UML
EXPRESS
EXPRESS
EXPRESS schema
in XML according
to Modules Repository
U to E
Stylesheet
E to U
Stylesheet
EEP
EXPRESS
XML
XSLT
Stylesheet
Processor
UML
Project File
WinZIP
UML model in
XML according
to XMI standard
XMI
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Possible EXPRESS/UML Evolution
1. UML = SDAI for implementors (Part 25)
– Treat UML as just another language like SDAI/C++
2. UML = EXPRESS-G for modellers (exff)
– Use UML diagrams instead of EXPRESS-G with no
effect on EXPRESS
– Could satisfy the need for EXPRESS 3 Operations, etc.
3. UML = EXPRESS interoperability for all (E 3?)
– make them "the same", modellers and implementors
use whatever suits them
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Conclusion
• S4W provides huge opportunities for STEP
implementation
• SC4 should focus on the “semantics” that have
been agree internationally over the past 15 years
– However, SC4 should give up control of many aspects
of the standards involved during implementation
• SC4 should formally adopt OMG and W3C
standards for implementation and “interoperate”
for modelling where ever possible
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All Presentation Material Copyright Eurostep Group AB