HRT Hood

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HRT Hood

• By (Names removed)

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What is HRT Hood

• Hard Real Time Hierarchical Object Orientated
  Design
• ADA orientated design method first contracted
  development of HOOD was by the ESA in 1986/7
• Used for Prioritizing over system processes in
  most real time software design stages.

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What is HRT Hood (Cont)

• Sponsored by ESA and UK Defence Research Agency
• Addresses the concerns of hard real time.

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Where is it used

• Military
• ESA
• ADA programming
• Columbus software Development Environment/SDE

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HRT Hood Activities for architectural design

• The logical architecture design activities
• Used to satisfy the functional requirements
• The physical architecture design activity
• Takes these requirements, other constraints into
  account, and non-functional requirements

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What is a hard real time system

• A system which has components which must produce
  timely services, failure to produce a service
  within the required time interval may result in
  severe damage to the system or the environment,
  and may potentially cause loss of life.
• Definition by Burns and Wellings HRT HOOD 1995

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• Allows timing attributes to be associated with
  objects.
• Provides a framework from within which a
  schedulability approach can be defined and the
  analysis of the terminal objects undertaken.
• Provides the abstractations with which the
  designer can express the handling of timing
  errors.

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• HRT HOOD facilitates the logical architectural
  design of a system by providing different object
  typed - Passive, Active, Protected, Cyclic and
  Sporadic. Which active objects are moved to
  background activities and must be transformed
  into one of the above types before reaching the
  terminal level

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Diagrammatic representation of HRT-HOOD

• Shows the hierarchical decomposition of a parent
  object into 2 child objects

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HRT Hood Example

• Mine drainage System
• Written in Ada which shows the typical
  characteristics of embedded real time systems

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The End

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