Back to Basic SDL

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Back to Basic SDL
Engineering background Reason for complexity
Defining basic SDL

• Rick Reed TSE Ltd
• Chairman SDL Forum Society

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System viewpoints
Engineering Background Reason
for Complexity Defining Basic SDL
engineer with view
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ITU-T Formal Languages for Software Engineering

• ASN.1 data to encode/decode
• MSC interaction sequences
• SDL stimulus/response behaviour
• TTCN behaviour validation
• other issues
• requirements modelling
• deployment

Engineering Background Reason
for Complexity Defining Basic SDL
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Methodologyof Z.100 Supplement 1
UML, URN??
UML, URN??
ASN.1
MSCSDL
Engineering Background Reason
for Complexity Defining Basic SDL
TTCN
???
C, C, ???
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Growing complexityaddition of concepts

• 1976 - simple state machine models
• 1984 - data, macro, partitioning
• 1992 - TYPE, remote procedure
• 2000 - agent,interface, exception
• Users (and tool makers) complaining
• the language is too large!

Engineering Background Reason
for Complexity Defining Basic SDL
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Typical extended finite state machine BitStuff
Engineering Background Reason
for Complexity Defining Basic SDL
/ INTERFACES IfRawPayload IfLineBits defined
elsewhere /
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Informative elements -UML style class models
Associations
Engineering Background Reason for Complexity Def
ining Basic SDL
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Key required features

• Data types, value names, variables
• Signals, Gates and Channels
• Finite State machine types with
• Start, Input, Transitions
• Timers (start, stop, cause event)
• Assignments, Decisions, Output
• Procedures
• Finite State machine instance (sets)
• Priority? None? Continuous Signal? Save??

Engineering Background Reason for Complexity Def
ining Basic SDL
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Basic SDL elements
Structure
x
Engineering Background Reason for Complexity Def
ining Basic SDL
Action
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Data typesASN.1 and SDL-2000

• ASN.1 includes
• BOOLEAN, INTEGER, BIT STRING, OCTET STRING,
  ENUMERATED , SEQUENCE (OF), SET (OF), CHOICE
• SDL can use ASN.1 types and adds
• operations for actions, variables, inheritance,
  OBJECT and pid types
• ASN.1 has encoding rules
• SDL (currently) does not

Engineering Background Reason for Complexity Def
ining Basic SDL
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Language usage
enterprise
Engineering Background Reason for Complexity Def
ining Basic SDL
URN, UML
information
technology
MSC
SDL
ASN.1, SDL
design
computational
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The way forward

• SDL as a design/programming language
• Separation of short hands and advanced features
• Further simplification
• Further features!!?
• Basic core SDL (Z.100 revised)Z.101 ...
• Is SDL environment concept adequate
• Unification - costs/benefits?