ROPES

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ROPES

• Rapid Object-Oriented Process for Embedded Systems

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ROPES process artifacts
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The ROPES Macro Cycle

• Analysis
• Requirements Analysis
• Systems Analysis/Engineering
• Object Analysis
• Design
• Architectural Design
• Mechanistic Design
• Detailed Design
• Translation
• Testing

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Analysis

• Identification of all aspects of the product that
  are required for correctness

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Analysis Model Artifacts
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Requirements Analysis

• Extracts requirements from customer as
• use cases, scenarios
• statecharts
• constraints
• Activities
• Create Use Case model
• Identify and characterize External Events
• Define behavioral scenarios (system dynamic
  behavior)
• Identify constraints, required interfaces to
  other systems and performance constraints

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Requirements Analysis (2)

• Determine large scale clumps and refine their
  behavior
• Identify actors in the external environment
• Identify the semantics and characteristics of the
  individual messages (including those that signal
  events) between the system and its actors
• Refine interaction protocols that use those
  messages
• Refine the interaction protocols, e.g. required
  sequences, pre- and postconditional invariants

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Create Use Case Model

• Identify Use Cases and associated Actors
• UC classification
• primary
• secondary
• safety-related
• Decompose UCs with generalization, uses and
  extends relations

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aPossibleUseCaseModel
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Messages Events

• Analyst has to
• find use cases and actors
• identify messages passing between the actors and
  the system

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Identify and characterize External Events

• by
• Associated actor (sender, receiver)
• Arrival pattern (periodic, episodic)
• Arrival time of message
• period and jitter (periodic msg)
• min inter-arrival interval or burst length
  (episodic msg)
• Message response properties
• deadline (for hard deadline msg)
• average response time (for soft deadline msg)

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Identify and characterize External Events (2)

• by
• State information
• pre-condition for the message
• protocol (acceptable message sequence)
• message data
• post-conditional invariants for the response

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External Event List example
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Actors

• Actors may be human users or externally visible
  subsystems and devices, such as sensors and
  actuators
• Common mistake to assume that actors must be
  people

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Actors (2)

• Whether the actor is a device used by a human or
  the human itself depends on the scope of the
  system.
• If the system development includes the
  development of devices that interact with a
  human, then the human is the actor.
• If the system must interact with existing (or
  separately supplied) devices that are, in turn,
  used by human users, then the interface devices
  are the actors because they are the first thing
  outside the system scope that actually interacts
  with the system.

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Messages

• During Analysisidentify the semantics and
  characteristics of the individual messages
  (including those associated with signaling the
  occurrenceof events) that pass between the system
  and its set of actors
• A message is an abstraction of the exchange of
  information between a sender and a receiver

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Messages (2)

• Have semantic content, i.e. the meaning of the
  message, e.g.
• the current temperature is 576 degreessensor
• insert the control rodactuator
• Have structure, also called signatureUsually a
  list of parameters during requirements analysis

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Messages (3)

• Pre- and postconditional invariants, which are
  ontological states assumed to be true prior to
  sending and after receipt of a message
• Important in systems where
• messages occur in one of a set of predefined
  sequences or
• the systems response to a message varies based
  on its state

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Messages, Events

• Events can precipitate the sending of a message
• An event is an occurrence in space and time,
  which has significance to the system

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Assignment Nr 2 (1)

• Task(s)
• Revise/Modify the Use Case diagram for the MySSe
  Project from the previous assignment. Take into
  account that the hardware is not within the scope
  of the project, i.e. the system boundary (and
  other elements, too) should be modified according
  to the fact that the system you develop is just
  the software, even if it is very closely coupled
  to the car HW and not the complete racing car.
• Identify and characterize External Events as
  described in this presentation and fill a table
  of similar format than found in the slide
  External Event List example

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Assignment Nr 2 (2)

• Deadline 20.03.2002 (Wednesday) 1000
• Grading The assignment affects the grading of
  the exam by -1, 0, or 1 assignment points.
• -1 assignment not done or clearly inferior to
  the requirements.
• The conversion between assignment points and
  exam points will be decided upon later.

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References

• Douglass, Bruce Powel. Doing Hard Time
  Developing Real-Time Systems with UML, Objects,
  Frameworks, and Patterns. New York
  Addison-Wesley, 1999.

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Behavior, event, signal

• This was not presented, its just extra
  information for those who would like a bit more
  insight

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behavior

• The term behavior refers to the observable
  effects of an operation or an event, including
  its results.
• Behavior refers to the ways in which things
  change.
• Functional aspect what the object does
• Classification
• Simple behavioran object performs services on
  request and keeps no memory of previous services
• State/State-driven/Reactive behavior

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event

• An event is a noteworthy occurrence that has a
  location in time and space.
• Within a state machine, the occurrence of an
  event can trigger a transition.
• An internal event passes between objects in the
  system an external event passes between the
  system and an actor.
• Within the UML, there are four kinds of events
• call events
• change events
• signal events
• time events

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Kinds of Events
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call event

• A call event is an event that represents the
  dispatch of an operation.

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change event

• A change event is an event that represents the
  satisfaction of a Boolean expression in response
  to a change to one or more of the values it
  references.
• A condition becoming true is shown with the
  keyword when followed by a Boolean expression

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signal event

• A signal event is an event that represents an
  object's reception of a signal.

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signal

• A signal is a specification of an asynchronous
  stimulus communicated between instances. The
  receiving instance handles the signal by a state
  machine.
• The term signal is a keyword that refers to a
  named object that is dispatched asynchronously by
  one object and rec eived by another object.

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