the design of xml-based model and experiment description languages for network simulation

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The Design of XML-Based Model and Experiment Description

Languages for Network Simulation

Andrew HallaganBucknell University

Dept. of Computer ScienceLuiz Felipe Perrone, Advisor

April 26, 2011

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3 General Network TypesClockwise from top: hardwired, wireless, and ad-hoc networks

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Nodes

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Channels

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Communication Between NodesBreaking a message up into packets.

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Ways to Study a SystemSource: Averill M. Law, Simulation, Modeling & Analysis

Physicalmodel

Experiment with the

actual system

Experiment with a model of the

system

System

Mathematicalmodel

Analytical solution Simulation

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Physicalmodel

Experiment with the

actual system


system

System

Mathematicalmodel



Costly, disruptive

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Physicalmodel

Experiment with the

actual system


system

System

Mathematicalmodel



Costly, disruptive

Not applicable

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Physicalmodel

Experiment with the

actual system


system

System

Mathematicalmodel



Costly, disruptive

Not applicable

d = v∙t

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Physicalmodel

Experiment with the

actual system


system

System

Mathematicalmodel



Costly, disruptive

Not applicable

Difficult, if not impossible

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A Simple Mobility ModelThe horizontal and vertical positions of the node are a function of SPEED and ANGLE, which are random variables distributed Normally and Uniformly, respectively.

X-position = f(SPEED, ANGLE)Y-position = g(SPEED, ANGLE)SPEED ~ N(SPEED_MEAN, 3.0)ANGLE ~ U(0, ANGLE_BOUND)

Model Inputs• SPEED_MEAN• ANGLE_BOUND

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A Simple Mobility ModelThe horizontal and vertical positions of the node are a function of SPEED and ANGLE, which are random variables distributed Normally and Uniformly, respectively.

X-position = f(SPEED, ANGLE)Y-position = g(SPEED, ANGLE)SPEED ~ N(SPEED_MEAN, 3.0)ANGLE ~ U(0, ANGLE_BOUND)

Model Inputs• SPEED_MEAN• ANGLE_BOUND

ModelDescription

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Factor Levels

ANGLE_BOUND15304560

SPEED_MEAN2.03.04.0

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Design Matrix

ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

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Design Matrix

ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

designpoint

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Design Matrix

ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

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Design Matrix

ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

Experiment Description

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Network ComplexitiesBandwidth, physical distance, network traffic, etc.

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Network ComplexitiesScale.

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Network ComplexitiesPhysical surroundings.

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Various simulator enginesResearchers have a number of simulator engines to choose from, including ns-2, ns-3, OPNET, CSIM, GloMoSim and MATLAB.

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ns-2

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ns-2

ns-3

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ns-2

ns-3

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ns-2

ns-3

GloMoSim

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ns-2

ns-3

CSIM

GloMoSim

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ns-2

ns-3

CSIM

GloMoSim

SWAN

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ns-2

ns-3

CSIM

GloMoSim MATLAB

SWAN

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Recap

• Networks are complex.• Modeling is difficult.• Experimentation isn’t straight-

forward.• Mistakes in this process have led to

credibility issues in network simulation.

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Solution: Automation

• Automation provides guidance that helps increase credibility of published research.

• Automate the modeling and experiment design processes.

• Validate experiments at multiple levels.

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Motivation for Network Simulation ResearchSource: J. M. Brase and D. L. Brown, Modeling, Simulation and Analysis of Complex Networked Systems. White paper.

“[The Department of Energy] must continue the development of next generation complex networked

systems that are more secure, less brittle to unexpected events, and more

controllable. For these emerging efforts to be successful, it is essential that a firm intellectual foundation be

provided for understanding and simulating large-scale networks.”

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SAFE

Simulation Automation Framework for Experiments

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ns-2 CSIM

GloMoSim MATLAB

SWAN

ns-3

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High-level view of the SAFE architecture.My work is concerned with the Model Description and Experiment Description inputs to this framework (in the yellow boxes).

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High-level view of the SAFE architecture.My work is concerned with the Model Description and Experiment Description inputs to this framework (in the yellow boxes).

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An HTML “anchor” element.This piece of HTML is valid XML. It is an a tag with an attribute href. The value of the href attribute is a URL string and the content of the a tag is the “Link to Google” string.

<html:a href="http://www.google.com">Link to Google</a>

Opening tag

Attribute Attribut

evalue

Element content

Closing tagNamespaceprefix

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NEDL: Experiment Description

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NEDL FunctionalityProvide ways to list experimental factors.

ANGLE_BOUND SPEED_MEAN

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A NEDL “factorlist” elementThe “factorlist” element lists all of the factor names referenced throughout the rest of the NEDL document.

<nedl:factorlist><nedl:factor>SPEED_MEAN</nedl:factor><nedl:factor>ANGLE_BOUND</nedl:factor>

</nedl:factorlist>

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NEDL FunctionalityProvide ways to list associated level values for each factor.

ANGLE_BOUND15304560

SPEED_MEAN2.03.04.0

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ANGLE_BOUND15304560

SPEED_MEAN2.03.04.0“Use the

values 3, 17, and 9.”

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A NEDL “memberof” elementThe “memberof” element associates a factor with a list of level values. The name was inspired by the terminology used to describe mathematical sets.

<nedl:memberof><nedl:factor>SPEED_MEAN</nedl:factor><nedl:listid>speed-values</nedl:listid>

</nedl:memberof><nedl:levellist id="speed-values">

<nedl:level>3</nedl:level><nedl:level>17</nedl:level><nedl:level>9</nedl:level>

</nedl:levellist>

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ANGLE_BOUND15304560

SPEED_MEAN2.03.04.0

“Use values of the form 5∙x +

2,where 0 ≤ x ≤

9”

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A NEDL “sequence” elementThe “sequence” element associates a factor with a sequence of level values. The sequence expression is built up using constants, variables, and further expression elements.

<nedl:sequence><nedl:factor>SPEED_MEAN</

nedl:factor><nedl:test>EQUALS</nedl:test><nedl:lconst>2</nedl:lconst><nedl:op>PLUS</nedl:op><nedl:rexpr>

<nedl:lconst>5</nedl:lconst><nedl:op>MULT</nedl:op><nedl:rvar>x</nedl:rvar>

</nedl:rexpr><nedl:where>

<nedl:range><nedl:var>x</nedl:var><nedl:lo>0</nedl:lo><nedl:hi>9</nedl:hi><nedl:delta>1</

nedl:delta></nedl:range>

</nedl:where></nedl:sequence>

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NEDL FunctionalityProvide ways to “prune” design points from the experiment space.

ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

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ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

“Remove the specific design

point where ANGLE_BOUND =

15and

SPEED_MEAN = 3.0.”

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A NEDL “exclusionrestriction” elementThe “exclusionrestriction” element specifies a whole or partial design point which should not be included in the final experiment space.

<nedl:exclusionrestriction><nedl:setting factor="ANGLE_BOUND" level="15"/><nedl:setting factor="SPEED_MEAN" level="3"/>

</nedl:exclusionrestriction>

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ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

“Remove any design points

where SPEED_MEAN =

4.0.”

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A NEDL “exclusionrestriction” elementThe “exclusionrestriction” element specifies a whole or partial design point which should not be included in the final experiment space.

<nedl:exclusionrestriction><nedl:setting factor="SPEED_MEAN" level=“4"/>

</nedl:exclusionrestriction>

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ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

“Link the factors ANGLE_BOUND

and SPEED_MEAN.”

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ANGLE_BOUND151515303030454545606060

SPEED_MEAN2.03.04.02.03.04.02.03.04.02.03.04.0

“Link the factors ANGLE_BOUND

and SPEED_MEAN.”

ANGLE_BOUND15304560

SPEED_MEAN2.03.04.0

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A NEDL “linkingrestriction” elementThe “linkingrestriction” element specifies factors which should be “linked” when creating design points.

<nedl:linkingrestriction><nedl:factor>SPEED_MEAN</nedl:factor><nedl:factor>ANGLE_BOUND</nedl:factor>

</nedl:linkingrestriction>

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NSTL: Model Description

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Creating an ns-3 script template.One can create an ns-3 script simply by removing certain hard-coded values and inserting special markers that correspond to the factors listed in a NEDL file.

// A bunch of ns-3 code before….norm = ns3.RandomVariable(“Normal”, 2.0, 3.0)unif = ns3.RandomVariable(“Uniform”, 0, 90)node.setSpeed(norm)node.setAngle(unif)// A bunch of ns-3 code after…

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Creating an ns-3 script template.One can create an ns-3 script simply by removing certain hard-coded values and inserting special markers that correspond to the factors listed in a NEDL file.

// A bunch of ns-3 code before….norm = ns3.RandomVariable(“Normal”, $SPEED_MEAN$, 3.0)unif = ns3.RandomVariable(“Uniform”, 0, $ANGLE_BOUND$)node.setSpeed(norm)node.setAngle(unif)// A bunch of ns-3 code after…

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Creating an ns-3 script template.Using the block element in NSTL, one can specify interchangeable code blocks to swap in an ns-3 script. Since two block elements are used, two scripts will be generated.

// A bunch of ns-3 code before…<nstl:block>norm = ns3.RandomVariable(“Normal”, $SPEED_MEAN$, 3.0)unif = ns3.RandomVariable(“Uniform”, 0, $ANGLE_BOUND$)node.setSpeed(norm)node.setAngle(unif)</nstl:block>

<nstl:block>norm = ns3.RandomVariable(“Normal”, $SPEED_MEAN$, 3.0)node.setSpeed(norm)node.setAngle(ns3.Constant(270))</nstl:block>// A bunch of ns-3 code after…

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Creating an ns-3 script template.Using the block element in NSTL, one can specify interchangeable code blocks to swap in an ns-3 script. The two different scripts are boxed in blue.

// A bunch of ns-3 code before…norm = ns3.RandomVariable(“Normal”, 5.0, 3.0)unif = ns3.RandomVariable(“Uniform”, 0, 30)node.setSpeed(norm)node.setAngle(unif)// A bunch of ns-3 code after…

// A bunch of ns-3 code before…norm = ns3.RandomVariable(“Normal”, 5.0, 3.0)node.setSpeed(norm)node.setAngle(ns3.Constant(270))// A bunch of ns-3 code after…

SPEED_MEAN = 5.0 ANGLE_BOUND = 30

DesignPoint

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Concluding Thoughts

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Concluding Thoughts

• NEDL and NSTL are markup languages; supporting modules can evolve.

• NEDL and NSTL not necessarily tied to ns-3.

• Working code generation a great benefit.

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Future Work

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Future Work

• GUIs for constructing NEDL documents.

• Repository of NSTL files created by experts.

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Thank you!

the design of xml-based model and experiment description languages for network simulation

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