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TopDown Protocol Design with UML

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Title: TopDown Protocol Design with UML


1
Top-Down Protocol Design with UML
  • Jason Shamberger
  • October 13, 2000

2
Outline
  • PicoRadio Application
  • Brief Introduction to UML
  • Design Methodology
  • UML Description of PicoRadio
  • Conclusion/Future Work

3
SmartBuilding A PicoRadio Application
  • Environmental control for an office building
  • Three types of nodes
  • Sensors measure some physical property either
    reactively or proactively
  • Actuators affect some change on the environment
  • Monitors controlling nodes, issue requests to
    sensors and commands to actuators
  • Data measured includes temperature, light,
    humidity, sound, air quality, smoke, security
    sensors, etc.

4
SmartBuilding A PicoRadio Application
  • Example subsystem controlling temperature for
    one workspace
  • Several temperature sensors
  • One actuator (AC vent)
  • One control monitor running an algorithm to
    maintain a constant temperature
  • One UI monitor (touchpad) allowing user to change
    the parameters in the control function to raise
    or lower the temperature
  • One system monitor which logs statistics, changes
    control functions systemwide to minimize power
    consumption, configures and debugs the system

5
What is UML (Unified Modeling Language)?
  • UML is a language designed to model
    object-oriented software systems.
  • Consists of several different types of diagrams
  • Use Case diagrams show environment interactions
    with system
  • Class diagrams show relationships between sets of
    objects that share common attributes and
    operations, give static structure of system
  • Interaction diagrams (Message Sequence Charts)
    show how objects interact dynamically
  • And more

6
Our Use of UML
  • Provide specifications for system we are
    designing
  • More formal description than English
  • Document the design process
  • NOT Simulating the system
  • Use another tool for this (OpNet)
  • NOT Implementing the system
  • Use another tool for this (VCC)

7
UML Notation
  • Most of our designs are class diagrams
  • Show relationships between classes
  • General relationship
  • Inheritance (is a) relationship
  • Aggregation (has a) relationship
  • Dependency (uses) relationship

8
Communication-Based Design Methodology
  • In a methodology for communication-based design
    developed by researchers in the Metropolis group
  • Processes communicate across channels
  • Initially assume the channel is ideal, so the
    input-output relation is the identity. If the
    behaviors of the processes are incompatible this
    can be fixed by adding behavior adapters
  • Where the channel is not ideal (or when we refine
    the channel to include its imperfections), we
    must add a channel adapter so that within an
    acceptable tolerance, the channel behaves as
    ideal

9
Layers
  • As we design a protocol, these channel adapters
    we add form layers of abstraction
  • Our design methodology starts at the top and
    descends through these layers
  • We simultaneously refine the communication medium
    to move closer to the real world conditions, and
    add channel adapters to cope with these conditions

10
Function to Architecture Mapping
  • At each layer we are performing a mapping
  • Map a functionality we wish to implement onto a
    refined hardware
  • The result is a new functionality, which has
    gained properties of the hardware, and possibly
    adapters

Level 0 Functionality
Level 0 Architecture
mapping
Level 1 Functionality
11
Specifications
  • System is a control system for building
    environment
  • Keeps properties of the environment (temperature,
    light, etc.) within certain tolerances
  • Data sizes and rates specified during meeting
    with CBE people
  • Use case captures interactions with environment

12
Use Cases
13
Level 0 Functionality
  • System has three global functions
  • Sensor maps physical property of environment
    into a number Ns.
  • Controller maps Ns to NA using some control
    algorithm.
  • Actuator maps NA to some physical property of
    environment.

14
Level 0 Functionality
15
Level 0 Architecture
  • Architecture consists of
  • A number of nodes, each has a location (can
    include some uncertainty) and other physical
    properties
  • An unspecified communication medium

16
Level 0 Architecture
17
Level 1 Functionality
  • Partition (distribute) the global functions in
    time and space
  • This is guided by the specifications, which state
    frequency with which sampling in time/space must
    occur.
  • Select number of sensor, actuator, monitor nodes,
    locate them to minimize power, either through
    simulation or analysis

18
Level 1 Functionality
19
Level 1 Functionality (cont)
20
Level 1 Architecture
  • Introduce a fully-connected communication medium
  • Given a message and an address, medium can
    deliver to any other node

21
Level 1 Architecture
22
Level 2 Functionality
  • Level 1 nodes had separate ports to send to
    different destinations
  • Add addressing adapters to map the end-to-end
    connections onto the fully connected network

23
Level 2 Functionality
24
Level 2 Functionality (cont)
25
Level 2 Architecture
  • Refine the communication medium to add
    attenuation properties
  • Refine the nodes to add transmission power
  • As a result, each node can only send messages to
    its neighboring nodes

26
Level 2 Architecture
27
Level 3 Functionality
  • As a result of the limited transmission range,
    have to add routing adapters and repeater nodes
    to make the network multi-hop
  • Design decisions at this level include choice of
    routing algorithm, whether to establish
    persistent connections

28
Level 3 Functionality
29
Level 3 Architecture
  • Decompose the communication medium into a set of
    channels

30
Level 3 Architecture
31
Level 4 Functionality
  • Each node can now transmit on one of many
    channels
  • Add MAC adapters to allocate channels and deal
    with collisions

32
Level 4 Functionality
33
Conclusions/Future Work
  • UML model has captured the big picture of the
    design.
  • Needs more refinement, especially at network/MAC
    layer
  • UML helps document the interfaces which will be
    used between each layer

34
Conclusions/Future Work
  • Interaction Diagrams can capture some
    inter-object behavior

35
Current/Future Work
  • Once we have described the system in UML,
    implement it in VCC

36
Future Work
  • UML functions well as a denotational language
  • Helps describe our design in a more formal way
    than English text, and is easy to read and
    comprehend
  • Can we add some semantics to UML so that it could
    be used as an input language to a system-design
    tool such as VCC?
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