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Applying Adaptive Middleware, Modeling, and Real-Time CORBA Capabilities to Ensure End-to-

End QoS Capabilities of Video Streams

BBN TechnologiesCambridge, MA

http://www.dist-systems.bbn.com/tech/QuO/

Craig Rodriguescrodrigu@bbn.com

617-873-4725

2nd TAO WorkshopArlington, VA, U.S.A.

July 19, 2002

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Unmanned Air Vehicle Scenario with ComplexEnd-to-End QoS Requirements

uav.navair.navy.mil/home.htm

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We Are Trying to Solve QoS Problem at Multiple Levels

• Application adaptation, using QuO adaptive middleware• Software modeling of QoS requirements, using General

Modeling Environment (GME) • Resource management of the network, using RTCORBA

and Diffserv

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Control Station Host 5

CORBA A/V Streaming Service

UAV Host 1

MPEGFile

Host 4

Wired

WirelessEthernet

VideoDistributorProcess 1

VideoDistributorProcess 2

VideoDistributorProcess 3

VideoSourceProcess

Filter

FilterContract

UAV Host 2

MPEGFile

VideoSourceProcess

Filter

FilterContract

UAV Host 3Video

SourceProcess

Scale/Compress

QualityContract

BandwidthManagement

BandwidthManagement

BandwidthManagement

ThroughputContracts

Displays

Control Station Host 6

ThroughputContracts

Displays

Control Station Host 7

ATRContract

ATRDisplay

High Level View of UAV Architecture using QuO Middleware (based on TAO)

… …

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Quality Objects (QuO)

• What do you need to do QoS?– need a way to specify QoS requirements– need a way to measure system performance– need a way to take corrective action

• How does QuO help you develop QoS applications?– QuO Contracts– QuO Sysconds– QuO Delegate Callbacks

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QuO Adds Specification, Measurement, and Adaptation to the Distributed Object Model

ApplicationDeveloper

MechanismDeveloper

CLIENT

Network

operation()

in args

out args + return value

IDLSTUBS

IDLSKELETON

OBJECTADAPTER

ORB IIOP ORBIIOP

CLIENT OBJECT(SERVANT)OBJECT(SERVANT)

OBJREF

CLIENT

DelegateContract

SysCond

Contract

Network

MECHANISM/PROPERTYMANAGER

operation()

in args

out args + return value

IDLSTUBS

Delegate

SysCond

SysCond

SysCond

IDLSKELETON

OBJECTADAPTER

ORB IIOP ORBIIOP

CLIENT OBJECT(SERVANT)OBJECT(SERVANT)

OBJREF

ApplicationDeveloper

QuODeveloper

MechanismDeveloper

CO

RB

A D

OC

MO

DE

LQ

UO

/CO

RB

A D

OC

MO

DE

L

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Application Level QoS Adaptation, Based on Recognition of a Target

ATR ATRQuoKernel

VideoQuality

Controller(MPEG)

Receiver(PPM)

VideoQuality

Controller(PPM)

Image Cropping

server

CameraDistributor

(PPM)

DVDview(PPM)

Distributor(MPEG)

Receiver(MPEG)

DVDview(MPEG)

Sender(MPEG)

(1) High grade, 10 fps, (2) Low grade, 2fps

(1) Low grade, ¼ size image filter, (2) High grade, remove filter

Filterqosket

Send frame Send alert

Video file

Change quality from (1) to (2)

Wireless

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Software Modeling Enhancementsto Improve the Design of UAV OEP Software

• Problem: End-to-End behavior in current UAV OEP software is designed by hand which is very time-consuming and error prone

• Solution: use COTS modeling tools, and make improvements to these tools where there are deficiencies

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Adaptive Quality Modeling Environment

• Software modeling tool from Vanderbilt University– Hierarchical dataflow

representationCompounds, primitives

– Parameters for component instrumentation and customization

• Middleware modeling– Services and system condition

objects

– Parameters for middleware instrumentation and customization

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UAV Modeling using GME Interpreter Plugins

General ModelingEnvironment

IDL Interpreter QuO Interpreter

QuOContract

CORBA IDL filecontaining callbackInterface methods

Matlab Interpreter

Matlab Simulink simulation

New

• GME uses interpreter plugins to input/output data about the model

• Import CORBA IDL, export model to QuO or Matlab

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Architecture of CORBA IDL Interpreter Plugin

• GME interpreters are based on Microsoft COM components

• CORBA IDL interpreter is a single Windows COM DLL which collocates IDL parser and Interface Repository

• IR is a database with a CORBA-based query API which can query the contents of an IDL file. After parsing IDL, we send interface information from IR to GME

• In future, we could create interfaces in the IR and export them to IDL files

TAO IDL compilerparser front-end

TAO CORBA InterfaceRepository

GME Interpreter API

IDL Interpreter DLL

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Ongoing and Future Work to Apply Software Modeling Techniques to UAV OEP

• Ease-of-use enhancements to GME Interpreters to make it easier to design end-to-end QoS control strategies

• Make more use of COTS tools like Matlab Simulink to do online and offline analysis of QoS control strategies

• Better integration with TAO and CORBA Component Model

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Enhanced Resource Management Capability:Diffserv Integration with RTCORBA

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What is Diffserv?

Diffserv Field(8-bits)

HeaderLength(4-bits)

Total Length(16-bits)

Source Address (32-bits)

Destination Address (32-bits)

TTL (8-bits) Protocol (8-bits) Checksum (16-bits)

Flags(3-bits)

Version(4-bits)

Identification (16-bits) Fragment offset (13-bits)

• Diffserv field: 6 bits of Diffserv Codepoint, 2 bits ECN• Each DSCP (0-63) specifies a Per-Hop-Behavior (PHB), which is a type of router-level QoS (RFC 2475)

IP Datagram Header

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Enhanced RTCORBA with Diffserv Capability Preserving End-to-End Priorities

• Existing priority in RTCORBA used for OS-level task scheduling across distributed nodes

• Our enhancement to RTCORBA uses this priority to set Diffserv field in IP packets associated with a specific CORBA call

• Network treats packets differently based on value of Diffserv field; can be used as another mechanism for end-to-end QoS

Middle-tierServer

Client QNXpriority

= 16

LynxOSpriority = 128

Server Solarispriority = 136

ServiceContextpriority = 100

ServiceContextpriority = 100

Router

DiffservCodePoint

= EF

DiffservCodePoint

= EF

Router

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Testing CORBA Calls with Diffserv Network Priorities

CORBA Request

CORBA Response

C++ Client(TAO)

C++ Server(TAO)

CORBA Request

CORBA Response

C++ Client(TAO)

Java Server(JDK 1.4)

CORBA Request

CORBA Response

C++ Client(TAO)

C++ Server(TAO)

1. Normal CORBA invocation

2. Diffserv Prioritized CORBA Invocation

3. Diffserv Prioritized CORBA Invocation against Java server

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How can we apply Diffserv to solve End-to-End QoS Problem?

• Give different types of CORBA calls different network priorities

– Give command messages higher priority than data messages

• Give different clients different network priorities depending on the relative importance of the clients

Video display 1

Video display 2

Video display 3

Video display 4

Router

• Utilize scheduling tools like RapidRMA to combine network priorities and OS-scheduling priorities for end-to-end QoS

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Distribution information

• Software available from our web site:

http://www.dist-systems.bbn.com/projects/AIRES/UAV/

• Help available from: quo-help@bbn.com

• More information about QuO

http://quo.bbn.com