Lecture 4 Component Behavioral Modeling with REMES

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Lecture 4 Component Behavioral Modelingwith
REMES
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Agenda

• Background and Motivation
• REMES
• Connecting REMES and ProCom
• REMES Editor
• Lab2

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Background and Motivation

• Embedded systems
• Computer that does not look like computer
• Part of a larger system or machine
• Typical requirements
• Low cost
• Constantly react to changes in the environment
• Dependability
• Compute certain results in real-time without
  delay
• Limited available resources
• Manage the growing complexity of software
• Need for solutions that
• Alleviate software complexity
• Ensure predictable system behavior

CBSE graduate course
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Background and Motivation
RB gt RC1
Repository
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Background and Motivation

• Challenge
• construct component model for ES design enriched
  with behavioral information
• support predictable system development and as
  such guarantee absence or presence of certain
  properties
• prediction methods should be available already at
  early design stage
• bottom-up ? resource analysis can guide the
  selection of components
• top-down ? resource analysis could help in
  correct decomposition of systems specification

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REMES behavioural language
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Classification of resources

• Resource consumption- annotated with c
• accumulated resource usage up to some time
  point
• c - rate of consumption over time
• Classification of resources
• discrete or continuous nature
• referable or non-referable

Resource Class Characteristics
A (memory) discrete c0 or cinf referable
B (CPU, bandwidth) discrete c0 or cinf non-referable
C (CPU, energy) continuous cn, n in Z - -inf,inf non-referable
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REMES REsource Model for Embedded Systems

• Behavioral model intended to describe the
  resource-wise behavior of interacting embedded
  components
• Behavior of a component is a mode
• Modes
• atomic
• composite

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REMES - modes

• Mode M (SM, V, In, Out, E, RC, Inv, CC)
• Control points In (Init point, Entry point),
  Out (Write point, Exit point)
• Variables (V) (boolean, natural, integer, array,
  clock, history variables)
• Actions over edges (E)
• discrete A (guard, body)
• delay/timed
• Constraints
• set of invariants (Inv)
• set of res. diff equations (RC)
• Conditional connectors (CC)
• Nested submodes (SM)

M
C
submode3
(guard, body)
Entry Point
submode1
submode2
Inv1 RC1
Init Point
Exit Point
Write Point
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Example1- internal behaviour of Control component
in REMES
Control
Credentials
tlt30,
cpu2
loginuserdata
mem30, t0
Init
loggedfalse
C
Entry
Exit
turnofftrue
Air_conditioning
loggedtrue
cpu10 eng2
Initialization resource memTA resource
cpuTC resource engTC tclock
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Analysing REMES based ES

• REMES modes have access to R1,, Rn
• Goal
• analyze various scenarios of systems resource
  usage
• Analysis model for REMES
• rtot total accumulated resource consumption for
  R1,, Rn
• r1,, rn accumulated consumption of R1,, Rn
• w1,, wn relative importance of r1,, rn

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Analysing REMES based ES

• Translating REMES into Priced timed automata or
  Multi PTA
• TA costs on locations and edges
• REMES atomic submode ? PTA location(s)
• REMES discrete edge ? PTA edge
• REMES discrete step ? PTA
  transition
• REMES conditional connectors are removed
• Automated translation
• Types of analysis
• Feasibility
• Optimal/ worst-case resource consumption
• Trade-off analysis

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Analysing REMES based ES

• PTA waits in location Start for system startup
• Init, Entry, Write and Exit locations created
• Transformation of Submode2
• Internal execution rounds - PTA edge connecting
  locations Write and Submode1
• Synchronization with other components

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Analysing REMES based ES
Model Checker (Uppaal Cora)
yes
PTA / MPTA
resource-aware property
error trace
Assumptions from hardware abstraction Memory
budget, Bandwidth, Cost model
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Analysing REMES based ES
REMES model of component behavior
ProCom component
Attribute Framework

• Managing and integrating properties
• Each ProCom component has an attribute with a
  complex value
• Reference to a REMES model file
• Reference to a mapping file between ProCom and
  REMES interfaces

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Connecting ProCom and REMES

• ProSave level
• trigger port ? REMES interface boolean
  variable
• data port ? REMES interface data variable
• ProSys level
• input message port ? REMES read boolean
  variable and REMES read data
  variable of the
• same
  type as the port type
• output message port ? REMES write boolean
  variable
  and REMES write data
  variable

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Example2- Temperature control system

• core is heated at some given rate
• core temperature should be maintained between a
  minimum and a maximum
• when max temp. is reached, designed to be cooled
  down by inserting one of two existing rods ,
  which cool at different rates R1 or R2
• a rod is available again after T time units

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Example2- Temperature control system

• Model of the architecture and behaviour
• System modeled with 3 ProSave components
• Each component has a behavior depicted by a REMES
  mode
• Assume memory and cpu usage
• Formal analysis
• ProCom REMES ? PTA

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Example2- Temperature control system
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Example2- Temperature control system
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Example2- Temperature control system Analysis
in Uppaal
Just for illustration!
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Questions ???
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REMES tool-chain
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REMES tool-chain

• The REMES tool-chain consists of
• REMES model editor
• REMES simulator to test timing and resource
  behavior prior to formal analysis
• Automated transformation from REMES to PTA for
  formal analysis and UppaalLite editor

CBSE graduate course
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REMES editor
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REMES language elements
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• Composite mode ?
• Compartments ? for declaration variables,
  resources, constants

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REMES language elements

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• Submodes ?
• Invariant time is allowed to pass until
  invariant is violated
• Non-lazy does not contain any.invariant, Time
  is allowed to pass in a non-lazy mode until at
  least one of the guards of the outgoing discrete
  actions evaluates to true
• Urgent time is not allowed to pass (invariant
  is false)
• .

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REMES language elements
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• Input and output ?
• Init-, entry-, exit-, write points (local exit
  points not presented here)

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REMES language elements

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• Control flow
• Edges with guards and actions ?
• Conditional connectors ?

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Introduction to Lab2
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Objectives

• Learn how to model behaviors of component-based
  embedded systems
• Model internal behavior of components
• Think about modes, actions, resources, invariants
  etc.
• Get familiar with the REMES editor

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Expected Output

• Same system as for Lab1
• Archive files only (no folder) named
  Lab2_X_Y.zip where X_Yfirst student
  name_second student name
• 1 report explaining your design choices
• The Project folder for your system
• Individual work/ group of two students
• And nothing else!
• Do not copy solutions from others !

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Deadline

• Thursday 21 February 2013 2359 (FIRM Deadline!)
• If you submit your work late, you fail one
  submission opportunity
• Remember
• Lab2 needs to be aproved for passing the course

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The assignment

• In 2 exercices
• Modelling behavior of simple Touch-Lamp system
• Modeling behavior of an abstracted version of a
  Baking Conveyor System

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Exercise 1- Touch Lamp System

• Lamp has two modes of light operation
• Dim 1 touch
• Bright 2 successive touches within 15 sec

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Exercise 2- Industrial Baking Conveyor System

• Main parts
• Oven
• Conveyor Belt
• Orchestrator

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Usage Scenario
Ensure that the conveyor belt and the oven are
working together
Orchestrator
Oven
Conveyor Belt
Carries the cookies from point A to point B in
passing by the oven
Oven monitors the temperature and humidity and
determines 1. if the heat should be increased or
decreased and 2. displays the status of the
cookies
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Exercise 1 and 2- What do you need to do?

• To model the behaviour of the system components
• Lamp component for Exercise 1
• Orchestrator, Oven and Conveyor Belt component
  for Exercise 2
• Tips
• Start by understanding REMES
• think about different types of modes that exist
  in REMES
• Use pen and paper before using REMES editor
• Once you are sure of your solution. Model it in
  the REMES editor

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Questions ???