International Telecommunication Union
Use of ITU-T Formal
Languages
Amardeo Sarma
NEC Europe Ltd.
© ITU-T Study Group 17
Current status of use of
ITU-T formal languages
o ETSI
• comprehensively and successfully used ASN.1, SDL,
MSC and TTCN
• High-level MSC popular
• TTCN-2  TTCN-3
o IETF
• Some impact of SDL in IETF already in the OSPF area
and through special IETF sessions
• EU Project Daidalos plans to model protocols with
UML/SDL/MSC and contribute to IETF
o Nokia has successfully used ITU-T languages
• Protocol emulators useful to check change requests
• Lot of ASN.1 use
• TTCN-2  TTCN-3
© ITU-T Study Group 17 2004
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Observation on the state of
things today
o UML use is growing everywhere and has
become a marketing factor
o Tool vendors use UML with SDL/MSC,
SDL/MSC are sometimes hidden
o Not only the actual work to be done at
ITU-T, their marketing becomes
increasingly important
• Should SDL, TTCN and MSC be separately
marketed or as part of UML
o Discussion on simplification of SDL remains
controversial
• Integration with testing or not?
• Clarify how to simplify languages
© ITU-T Study Group 17 2004
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Differentiating factors:
still relevant?
o Real-time, distributed communicating
o
o
o
o
systems
Formal, allowing verification and
validation
Many languages with a graphical syntax
Commercial tool support
Catering for users both in Industry and in
Standards bodies (SDOs), e.g. ITU-T SG 11
These have been our
differentiating factors and strengths
© ITU-T Study Group 17 2004
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From previous presentation:
Co-Evolution of Techniques
o SDL/MSC and UML have co-evolved
o Full UML 2.0 recognition planned by
ITU-T
o SDL graphical presentation syntax for
UML is an option
o A UML profile should be an ITU-T
Recommendation and OMG Standard
o Arrangement with OMG such as joint
meetings to promote co-evolution
and save meeting time.
© ITU-T Study Group 17 2004
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From previous presentation:
Language development goals
o Controlled simplification of ASN.1, SDL,
MSC and TTCN
o Abstract (more convenient) view for
standards developers w.r.t. ASN.1, SDL
o Combine ASN.1, SDL, MSC and TTCN via
UML
• Ensure co-ordinated development
• Applies to eODL and URN as well
o Provide professional support and more
(free) tools
© ITU-T Study Group 17 2004
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A proposal: The future of
ITU-T formal languages
o Co-Evolution of UML and ITU-T languages
o
o
o
o
o
remains important
UML Profiles are on the agenda
Involve input from the VeUML work
Simplification is on the agenda
Free tools are required, UML profile will
help!
Use of ITU-T Languages
• IETF is an important if not essential body
for input using ITU-T languages
• NGN needs formal languages  this is an
opportunity
© ITU-T Study Group 17 2004
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