A 3level approach for

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A 3-level approach for Control Systems GUI
modeling with COOPN M. Risoldi
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Outline

• Introduction to the problem
• 3 levels of modeling
• System model
• Logical model
• Visual model
• Levels interaction and transformation
• Status and outlook

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Problem

• Modeling a GUI for a control system using COOPN.
• Control system a system used to monitor the
  state of a hardware apparatus, sending commands
  to and retrieving responses from its components.
• Components can be organized in a hierarchy.
• Commands can be sent to components, with or
  without parameters, to change or poll their
  state.
• Components can send messages to the interface
  notifying their state.
• External events can change component states
  independently from the interface.
• The communication between the interface and the
  system is subject to failures.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Different aspects of the problem

• There are 3 aspects to this problem
• Modeling the objects and their hierarchy
• Modeling the interface logical aspects
• Modeling the interface visual aspects

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook

• Each can be taken into account with a level of
  modelization
• A system model level
• A logical model level
• A visual model level

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System model level

• In the system model level we model the objects
  and their hierarchy.
• The objects themselves are represented by
  classes. This allows for different objects, and
  different types inside an object.
• Objects have methods and gates which express low
  level behavior and properties pertaining to the
  single object.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
MyObject
method1
s
method1 will read the internal state of the
object and make it available on gate1 method2
will change the internal state of the object and
make it available on gate1
s
gate1 _
state
s
method2 _
t
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System model level

• The hierarchy of objects is attained through the
  use of contexts associated to objects.
• Contexts can be nested to express a composition
  of objects.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
MyObject
OtherObjectContext
OtherObjectContext
OtherObject
OtherObject
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Logical model level

• Focuses on interaction at the level of the
  interface (but not considering the nature of the
  interface).
• At this level, objects are mapped to their
  logical representation, i.e. they acquire methods
  and properties which can be (in an abstract way)
  pertaining to a GUI object.
• Example toggle, show details, show children
  objects
• Must interact with the System model by
  translating actions to corresponding actions on
  objects.
• Must also retain abstract information about the
  visual status of an object, such as visibility,
  or a state indication. How this will be
  represented in the GUI is a task for the visual
  model level.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Logical model level

• Similarly to the System model level, the Logical
  model level has
• classes representing the GUI control
• contexts enclosing classes which allow
  interaction with other levels and hierarchy of
  controls

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
MyLogObjContext
method1
gate1 _
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Visual model level

• This is attaining the actual visual
  representation of objects in the interface. It
  should couple logical objects with an avatar,
  their visual projection, which can be of
  different nature (tree node, icon, 3d model,
  widget).
• The avatar must allow interaction with the
  logical object (i.e. show its methods and
  properties). Also, it should probably add actions
  related to the used visual paradigm (e.g. open a
  tree node).
• At this level, visual behavior of objects should
  be modeled (e.g. show all children should move
  the visualization down one level, whatever this
  means), giving a visual follow-up to abstract
  actions of the logical level.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Interaction of levels
Visual model
User
Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
Properties Return values in abstract format
Methods on interface objects
Logical and Visual levels have some
methods/properties which stop at that level, and
others which are sent/taken from the levels above
and below.
Logical model
Physical objects methods
Properties notification
System model
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Modeling failures

• Failures have to be taken into account that can
  be of different nature
• Physical failures in an object
• Physical failures in the control of an object
• Communication failures between levels
• (others?)
• These have to be modeled for simulation. It can
  be done with
• additional states/variables and conditions
• appropriate methods and gates to simulate
  failures/repairs

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Climbing levels
Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Why two levels for interface?

• The logical interface model is stable once
  defined the nature of the interaction, it is
  independent on the visual paradigm adopted.
• The visual level is incidental in principle, a
  logical interface can be remapped to any
  (reasonable) visual paradigm.
• Possible outcome use code bricks that can be
  assembled to automatically generate a GUI from
  the logical model.
• Have a Logical ?? Visual interface which allows
  to
• understand the type of interaction with the
  control
• associate a widget to it
• This could be skinnable different visual
  paradigms could be selected, and generate
  different interfaces for the same Logical model

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook
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Status and Outlook

• Currently, the System and Logical model have been
  modeled and simulated in CoopnBuilder using a
  very simple example (a switch and light bulb
  control system).
• Upcoming work
• Model and simulate failures
• Model and simulate hierarchy (more complex
  system)
• Verify scalability
• Prototype a visual model in CoopnBuilder
• Consider automatic code generation from the
  model
• Target scenario
• Have a methodology which, from a Control System
  specification, can translate (automatically?) to
  COOPN and generate a GUI for it.

Introduction 3 levels System Logical
Visual Interaction Transform. Status Outlook