This document provides an overview of the Architecture Analysis and Design Language (AADL). AADL is a text-based language used to model embedded systems. It separates system architecture into software and hardware components, and separates component types from their implementations. AADL models can be used to generate code, perform analysis, and capture system topology, properties, and modes. Key features include different component types, ports, connectors, bindings, flows, and annexes for extensions.

1. *
AADL Overview
Brief and Pointless
Ivan Ruchkin
November 12, 2012
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*Architecture Analysis and Design Language

2. Agenda
● Intro
● Elements
– Components
– Ports
– Connections
● Special features
– Modes
– Flows
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– Annexes

3. Definition
● What it is:
– (Systems Engineering) A high-level system
specification language, specialized on real-
time and embedded systems.
– (Architecture Description) an ADL for the
domain of avionics and automotive.
● What is it not:
– Not UML
– Not programming language
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4. Use of AADL
● Capture topology of architecture + properties
– Specific to embedded real-time systems
● Generate code
– C, Simulink, UML
● Do analysis
– For example, end-to-end latency
– May extend with annexes
– Tools not included into AADL
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5. Timeline
● 2004: the Society of Automotive Engineers
(SAE) released AADL v1.0.
– 4 annexes
● 2009: AADL v2.0.
– Several major additions and improvements, +3
annexes
● 09/2012: AADL v2.1.
– Minor fixes, +3 annexes
* This presentation considers 1.0 5

6. AADL Notations
● Plain text
● Graphical
● XML
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7. AADL Graphic Notation
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8. Component Base Types 1 of 2
● Software (“application”):
– Thread – a unit of execution
– Process – a unit of protected address space
– Thread group – a logical grouping of threads
– Data – a unit of information
– Subprogram – a callable unit of code
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9. Component Base Types 2 of 2
● Hardware (“execution platform”):
– Processor – an executer for threads
– Memory – a binary data storage
– Device – a component that interfaces with
external environment (transducer)
– Bus – a communication channel
● Composite
– System – a composite component
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10. Separation of Type and Impl
● Component type: externally visible
– Extends
– Features
– Flows
– Properties
● Component impl: externally invisible
– Extends, refines
– Subcomponents, calls, connections
– Flows
– Modes
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– Properties

11. Example: Component (text)
process control_processing
features
input: in data port sensor_data;
output: out data port command_data;
end control_processing;
process implementation control_processing.speed_control
subcomponents
control_input: thread control_in.input_processing_01;
control_output: thread control_out.output_processing_01;
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end control_processing.speed_control;

12. Example: Component (diagram)
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13. Example: Thread Lifecycle
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14. Example: Device
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15. Ports
● Data ports
– Typed state data, no queuing
● Event ports
– Event data, may be queued
● Both: event data ports
– Typed data and event with queuing.
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16. Connectors (conceptually)
● Port dataflow
● Shared data access (data or bus)
● Subprogram call
– By value
– By reference
– Global
* Not first-class elements, unlike e.g. ports
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17. Binding
● For a model to be complete:
– Each thread bound to processor
– Each process, data, and port bound to
memory
– Each interprocessor communication is bound
to bus
– …
● No language primitives to bind
– Assuming it is done automatically
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18. Modes
● State of a component
● Part of the component's state machine
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19. Example: Modes
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20. Flows
● An abstract information path from the source
to the sink
● Directional
● Type contains source, sink, and path
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21. Annexes
● Language extensions (not libraries of types!)
● Needs to be approved
● Currently around 10:
– Notation annexes (graphical, XML)
– Error model annex
– Behavior annex
– ...
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22. Summary for the Language
● Separation of software and hardware
● Separation of type and implementation
● Specific semantics: properties and constraints
● Special features: modes, flows
● Generation to code, Simulink, UML
● Analysis tools - standalone
● Analogy to views: implementations
– Unified through shared types 22

23. References
● P. Feiler, D. Gluch, J. Hudak, B. Lewis.
Embedded System Architecture Analysis
Using SAE AADL. CMU/SEI-2004-TN-005.
June 2004.
● P. Feiler, D. Gluch, J. Hudak. The
Architecture Analysis & Design Language
(AADL): An Introduction. CMU/SEI-2006-
TN-011. February 2006.
● P. Feiler, J. Hudak. Developing AADL Models
for Control Systems: A Practitioner’s Guide. 23
CMU/SEI-2006-TR-019. October 2006.

24. Thank you!
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