Quality network load information improves performance of adaptive applications

188 Pages·2.9 MB·English

by  Kresho, John P

NPS ARCHIVE
1997 0°1
.
KRESHO,
3.
NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
QUALITY NETWORK LOAD
INFORMATION IMPROVES
PERFORMANCE OF ADAPTIVE
APPLICATIONS
by
John P Kresho
September 1997 **
Thesis Advisor: Debra Hensgen
Second Reader: Taylor Kidd
Thesis
K8624163
Approved for public release; Distribution is unlimited.
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September 1997 Master'sThesis
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QualityNetworkLoadInformationImprovesPerformanceofAdaptiveApplications
AUTHOR(S)
Kresho,JohnP
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13. ABSTRACT (maximum 200words)
TheJointTaskForceReferenceArchitecturerequiresaCommsServertoaidclientapplicationsinadaptingtochanging
network loadsbyapprisingthemofcurrentandexpectedloads. ThecurrentCommsServerimplementationestimatesthenetwork
loadby sending varioussizedpacketsandreportingrawperformancestatisticstotheclient. This implementationpresentsthree
problems: (1)clientsinterpretthe statisticsautonomously, (2)statisticsare inaccurateduetothe instantaneous collectionprocedure,
and(3)clientsalsorequirethe stateofotherresourcestomake informeddecisionsconcerningadaptation. Developmentofanew
CommsServerdesign, whichsolvestheseproblems, isneeded.
ThisthesisdevelopsanewComms Serverdesignanddetermines, throughsimulation,whetherprovidingamoreaccurate
estimateofthe loadcouldpermitusersofadaptive applicationstoobtainbetterperformance. Simulationswererunusingmany
different situationalparameters. Boththeaverage sizeofthedatasuccessfullytransmitted, andwhetheranapplicationmetits
deadline, wererecorded.
Theresultsofthesesimulationsshowthatclientsoftheexisting Comms Serverperformmuchbetterbecausetheyadapt, butin
somecases 14%to 30%ofthemessagesdonotarrivebytheirdeadline. However, abetterdesignthatmoreaccuratelyestimates
loadscoulddeliveratleast 96%ofthemessagesontime.
14. SUBJECTTERMS 15. NUMBEROFPAGES
SoftwareArchitectures,AdaptiveApplications, ResourceMonitoring,NetworkSimulation 185
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QUALITY NETWORK LOAD INFORMATION IMPROVES
PERFORMANCE OF ADAPTIVE APPLICATIONS
John P Kresho
Captain, United States Marine Corps
B.S., Cornell Univerity, 1991
Submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE IN COMPUTER SCIENCE
from the
NAVAL POSTGRADUATE SCHOOL
September 1997
Kv-e.sVio "X
;
QyOt-IYXNOXLIBRARY
POSTGRADUATESCHOOL
C.A <53343-5101
ABSTRACT •
The Joint Task Force Reference Architecture requires a Comms Server to aid
client applications in adapting to changing network loads by apprising them of current
and expected loads. The current Comms Server implementationestimates the network
load by sending various sized packets and reporting raw performance statistics to
the client. This implementation presents three problems: (1) clients interpret the
statistics autonomously, (2) statistics are inaccurate due to the instantaneous collection
procedure, and (3) clients also require the state of other resources to make informed
decisions concerning adaptation. Development of a new Comms Server design, which
solves these problems, is needed.
This thesis develops a new Comms Server design and determines, through
simulation, whether providing a more accurate estimate of the load could permit users
of adaptive applications to obtain better performance. Simulations were run using
many different situational parameters. Both the average size of the data successfully
transmitted, and whether an application met its deadline, were recorded.
The results of these simulations show that clients of the existing Comms Server
perform much better because they adapt, but in some cases 14% to 30% of the mes-
sages do not arrive by their deadline. However, a better design that more accurately
estimates loads could deliver at least 96% of the messages on time.
VI
TABLE OF CONTENTS
INTRODUCTION
I. 1
BACKGROUND
A. 1
MOTIVATION
B. 3
PURPOSE
C. 4
ORGANIZATION
D. 5
OVERVIEW OF THE JTF REFERENCE ARCHITECTURE
II. 7
USER ENVIRONMENT
A. 8
PRE-SPECIFIED APPLICATIONS LAYER
B. 9
1. Task Force Staff Process Management 9
2. The Situation Assessment and Planning Module 10
3. The Coordination, Communication, and Control Module . 10
C. GENERIC SERVICES 10
INFRASTRUCTURE FOR COLLABORATIVE OBJECT MAN-
D.
AGEMENT, COMMUNICATIONS AND COMPUTING .... 12
SUMMARY
E. 13
DESIGN OF THE VTC APPLICATION
III. 15
TASKTOOL
A. 16
WORKFLOW SERVER
B. 17
1. JTF ATD Object Definition 18
2. Objects of WorkFlow Server 19
3. TaskTool to WorkFlow 20
4. Use of the Trigger Server 20
C. BASIC STRUCTURE OF OUR APPLICATION 22
I). WISE USE OF BANDWIDTH 25
OVERVIEW AND TESTING OF THE COMMUNICATIONS
IV.
SERVER
33
Vll
OVERALL CONCEPT OF THE COMMUNICATIONS SERVER
A. 33
OUR EARLY EXPERIENCE WITH THE COMMUNICATIONS
B.
SERVER
34
1. Testing the Functionality 37
CONCLUSIONS FROM THE TESTING
C. 45
SIMULATION EXPERIMENTS
V. 47
A. ADAPTATION STRATEGIES 47
ASSUMPTIONS
B. 48
SIMULATION PARAMETERS
C. 50
1. Communications Server Bandwidth Prediction Values 52
. .
2. Random Seeds Used 52
D. RESULTS 52
1. The Need for Adaptation 53
2. The Effect of Varying Weights 53
3. Strategy 1 vs. Strategy 2 54
4. Determining How Accurate Server Estimates Should Be 54
.
CONCLUSIONS
E. 60
VI. MATHEMATICAL FORMULATION OF THE PROBLEM 67
. .
A. ADAPTIVE APPLICATIONS NEED TO KNOW ABOUT ALL
RESOURCES
67
THE FORMAL MODEL
B. 70
PROPOSED ARCHITECTURE SOLUTION
VII. 77
OVERVIEW OF OUR ARCHITECTURE
A. 78
B. THE CLIENT LIBRARY 79
C. RESOURCE STATUS SERVER 80
RESOURCE REQUIREMENT DATABASE
D. 82
E. THE SCHEDULING SERVER 82
PRIORITY MODELS AND ECONOMIC MODELS
F. 83
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