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Scheduling in SDL Simulation Application to
Future Air Navigation Systems
Frédéric Boutet (Telelogic) Gilles Rieux
(AEROSPATIALE-MATRA AIRBUS) Yves Lejeune
(Telelogic) Eric Choveau (AEROSPATIALE-MATRA
AIRBUS)
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The FANS system
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ATSU Layers
Inter-node Priority Level
datalink (dialogs) management between aircraft
and ATC (Air Traffic Control) center
ADS
AFN
CPDLC
Server for ATC HMI Management
Server for ATC On Board Integration Management
ATC server layer
Host Platform
Data Acquisition

Ground on-board data
Automatic Code Generation From SDL
Specifications (1 node)
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High level specifications
SDL specifications
Verification by Simulation
Code Generation
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Simulation Code generation languages
Diag. 1
Diag. 2
LOGsim
LOGsim
Lg
Lg
Diag. 4
Diag. 3
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Get closer to the application Reduce complexity
Scheduling Rules
Test cases (good erroneus behaviours)
Generate Test
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Scheduling in SDL - Mapping or deployment

• each agent Í in a node
• Physical or logical
• interpretation of nodes
• Possible Use of UML
• A node can be a class

Node (partition)
Mapping
Node (partition)
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Scheduling in SDL - Intra-node scheduling policy
 Internal events always first 
External Events
priority
Internal Events

Node
Node
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Scheduling in SDL - Inter-node scheduling policy
Fixed node priority policy
See ATSU layers slide ...
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Scheduling in SDL - SDL Semantics modifications
SDL semantics E is fired
A process instance queue contains
External event E
Internal event I
Intra-node policy I should be fired

• Implement a new ouput function that puts a
  message at a specific place in the queue.
• Apply a re-ordering algorithm to the queue.

New SDL behaviours !
The paper gives an example of a re-ordering
algorithm.
Internal event I
External event E
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Scheduling in SDL - Implementation in ObjectGeode

• Edition formal comments for specifying nodes
• Resources needed in simulation
• The goal language (a goal observer implements
  the scheduling policy)
• The filtering mechanism (pre-execution of
  transitions)

Initial list of fireable transitions
List of fireable transitions that
respect scheduling

• Works in
• interactive mode
• random mode
• exhaustive mode

Filtered by pre-execution
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Scheduling in SDL - ATSU SDL models
Aircraft console
ObjectGeode Simulator
Global ATSU Model
Ground console
Simulate and verify global behaviours comparing
to specifications
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Scheduling in SDL - ATSU SDL models
ObjectGeode Simulator
Node Model
OG Console
Single-node scheduling
Unit tests. Verify behaviours that cannot be
simulated with the global model
Test cases
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Scheduling in SDL - ATSU Future work
Get Closer to the application behaviour
Aircraft console
ObjectGeode Simulator
ATSU Global Model
Ground console
Multi-node scheduling
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Scheduling in SDL - Telelogic Future work
UML - SDL 2000 Integrated environment
Deployment Diagrams for both Simulator Code
generator
Predefined scheduling rules
Simulation driven by scheduling
Test Suite connection