POSTECH DPNM Lab

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Introduction

• Providing Quality-of-Service (QoS) to users of distributed multimedia services is a difficult problem.

• The service user must be given the capabiltiy to express his requirements for the receiving service in terms of QoS parameters familiar to him.

• It requires a vertically integrated architecture that can deliver end-to-end QoS guarantees at multiple levels of an entire distributed system.

• We present an object-oriented QoS management middleware for managing QoS of distributed multimedia services and applications.

• A key component in this middleware is QoS Management Service Object (QMSO), providing multimedia applications with QoS management service APIs.

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Related Work• Int-serv Architecture

– Provides controlled QoS for multimedia applications over an integrated services internetwork.

• OSI QoS Framework– Defines terminology and concepts for QoS and provides a model which id

entifies objects of interest to QoS in open system standards

• QoS-A– Provides a layered architecture of services and mechanisms for quality of

service management

• QuAL– Quality Assurance Language (QuAL) for the specification of QoS constrai

nts on underlying computing and communication platforms.

• Quality of Service for CORBA Objects (QuO)– Supports QoS at the CORBA layer and extends the CORBA functional Int

erface Description Language (IDL) with a QoS Description Language (QDL)

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QoS Management Framework

QoS Management API

MultimediaApp.

QMSO

QoS SpecificationQoS MappingQoS Monitor

Admission ControlQoS Negotiation

QoSMIB

QMSO

QoS SpecificationQoS MappingQoS Monitor

Admission ControlQoS Negotiation

QoSMIB

MultimediaApp.

Multimedia Session Service Object

QMIOMultimedia Communication

Service Object

QMIO

Network Service Object

QMIOSystem Service

Object

QMIOServiceObjects

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QoS Management Information Base (MIB)

• QoS MIB can be used to monitor and control QoS values in multimedia services

• Composed of 4 Informational Groups– Service, Application, System and Network

• QoS MIB can be extended by adding the service-specific QoS management information

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QMSO Services (1)• QoS Specification

– The value of QoS parameter can be acquired using the three methods

• device specification, off-line testing and on-line testing

• QoS Monitoring– QoS monitoring modes: a query mode and a report mode

– We use the report mode

• Negotiation and Renegotiation– The QoS parameters are exchanged between server and client throug

h peer-to-peer negotiation and layer-to-layer negotiation• peer-to-peer negotiation : between server and client

• layer-to-layer negotiation : between the layers

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QMSO Services (2)• QoS Mapping

– Maps one layer QoS parameters onto other QoS parameters and vice versa (bidirectional translation)

• One-to-one mapping, Mixing and Splitting (Demultiplexing)

• Admission Control– The QMSO performs admission control at both layers : system and n

etwork

– System level • device quality test, local schedulability test, end-to-end (EED) delay test

and buffer allocation test

– Network level• throughput test, rate control test and network EED delay test

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Procedure of QoS Services

Translating User Requirement to Application QoS

Admit resources for system

Negotiate System QoS with remote system

Translating into Network QoS

Admit network resources

Negotiate network QoS

User

Application

QMSO

accept

accept

StartServiceaccept

Translating Application QoS to System QoS

accept

reject

reject

reject

reject

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Prototype Implementation of QoS Management System

Objec t Management API APIs

<Legend>

SO : Service Object

MSO : Management Service Object

MIO : Management Interface Object

QMSO : QoS Management Service Object

QMIO : QoS Management Interface Object

MAESTROServices

Web Browser

OrbixWeb

MultimediaApplications

MIO NSO

SSO

CSO

SRSO

MIO

MIO

MIO

QMIO

QMIOQMSO

MSO

MIO

MIO

QoS Management API Mult imedia API

Web Server

ManagementApplications

QoSMIB

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Video Conferencing Example with QoS Guarantees

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Conclusion & Future Work• We presented a QoS management framework which includes QoS Ma

nagement Service Object (QMSO) and a generic QoS MIB. As a realization of the QoS management framework, object-oriented QoS management middleware has been developed.

• This provides distributed multimedia applications with QoS management APIs. It simplifies the development and maintenance of distributed multimedia applications, providing QoS guarantees.

• We also described our effort on the prototype implementation of a Web-based QoS management system for MAESTRO.

• The prototype QoS management system uses OrbixWeb to interface with the management server, which is implemented as a CORBA object.

• This QoS management middleware can be used to provide QoS in CORBA-based as well as non-CORBA-based multimedia systems.

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