Qualit dei servizi l approccio mais
Download
1 / 43

Qualità dei servizi – l’approccio MAIS - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

Qualità dei servizi – l’approccio MAIS. B. Pernici Politecnico di Milano Dipartimento di Elettronica e Informazione. Outline. Qualità dei dati e qualità del servizio Qualità del servizio in MAIS Classificazione delle dimensioni Specifica di dimensioni di qualità Lavoro futuro.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Qualità dei servizi – l’approccio MAIS' - kail


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Qualit dei servizi l approccio mais

Qualità dei servizi – l’approccio MAIS

B. Pernici

Politecnico di MilanoDipartimento di Elettronica e Informazione


Outline
Outline

  • Qualità dei dati e qualità del servizio

  • Qualità del servizio in MAIS

  • Classificazione delle dimensioni

  • Specifica di dimensioni di qualità

  • Lavoro futuro

(c) B. Pernici, Process Track, Milano, April 2004


Qualita dei dati e del servizio
QUALITA’ DEI DATI E DEL SERVIZIO

(c) B. Pernici, Process Track, Milano, April 2004


Dimensioni di qualita
Dimensioni di qualita’

(c) B. Pernici, Process Track, Milano, April 2004


Modello basato su prestazioni dei prodotti e dei servizi psp iq
Modello basato su Prestazioni dei Prodotti e dei Servizi (PSP/IQ)

(c) B. Pernici, Process Track, Milano, April 2004


Quality driven composition
Quality Driven composition (PSP/IQ)

  • Proposes a global approach to planning to optimally select component services during the execution of a composite service

  • Defines a quality model and a quality-driven service selection

L. Zeng, B. Benatallah, M. Dumas, J. Kalagnanam, Q.Z. Sheng,Quality Driven Web Service CompositionWWW 2003, Budapest

(c) B. Pernici, Process Track, Milano, April 2004


Quality driven composition1

Given a composite service the execution path and the execution plan are defined

Execution paths are sequences of states

Execution plans are execution paths in which each activity is performed by a service

The problem is to select for each activity the service that not only satisfies local requirements but also the global ones

Quality Driven composition

(c) B. Pernici, Process Track, Milano, April 2004


Quality model
Quality model execution plan are defined

  • According to the separation between service provider and service requester perspective also the quality definition depends on them

  • The service provider specifies SLS, i.e. the promises

  • The service requester selects the more appropriate quality level

  • The provider and the requester agree on SLA that is a set of selected SLS

(c) B. Pernici, Process Track, Milano, April 2004


Qualita in mais
QUALITA’ IN MAIS execution plan are defined

(c) B. Pernici, Process Track, Milano, April 2004


Mais enhanced service model
MAIS - Enhanced service model execution plan are defined

  • Besides the classical service model we could consider the context in which the service operates

  • The service context could be defined by (e.g.)

    • The channels

    • The time-zone

    • The location

  • Two models

    • Service provisioning model

    • Service request model

  • Quality of service

(c) B. Pernici, Process Track, Milano, April 2004


Quality of service
Quality of service execution plan are defined

  • Each service provides a particular quality

  • Even a service-based process must provide a quality

  • What is quality for services?

    • Performance issues (what it offers)

    • Economical issues (how much it costs)

    • Resource consuming issues (what it requires)

  • Quality parameters are specific to different domains

(c) B. Pernici, Process Track, Milano, April 2004


Multi channel adaptive information systems

QoS execution plan are defined

t

Multi-channel ADAPTIVE information systems

Accepted quality threshold

(c) B. Pernici, Process Track, Milano, April 2004


Quality parameters
Quality parameters execution plan are defined

  • Physical resources

    • How many CPUs, how many disks, …

  • Data resources

    • Timeliness, currency, availability, …

  • Channel

    • Bandwidth, latency, jitter, …

  • Provider

    • Pricing policy, payment forms , …

(c) B. Pernici, Process Track, Milano, April 2004


Sls example

<level id="low"> execution plan are defined

<framerate unit="fps">

<max>10fps</max><min>5fps</min>

</framerate>

<minresolution>320x200</minresolution>

<price currency="EUR">80</price>

<availability unit=“%">95</availability>

</level>

</levels>

<levels channel="PC-Eth-RSTP">

<level id="high">

<framerate unit="fps">

<max>40</max><min>31</min>

</framerate>

<minresolution>1024x768</minresolution>

<price currency="EUR">100</price>

<availability unit="%">95</availability>

</level>

<level id="medium">

<framerate unit="fps">

<max>30fps</max><min>11fps</min>

</framerate>

<minresolution>800x600</minresolution>

<price currency="EUR">90</turgia>

<availability unit=“%">95</availability>

</level>

SLS example

(c) B. Pernici, Process Track, Milano, April 2004


General architecture
General Architecture execution plan are defined

All the modules are placed in

the platform or in service/user

device according to their capability.

Each profile is composed by a local

and a global part.

E-Service Composition

Platform

Chooses the best e-service according

to user request

Invokes the chosen service

(c) B. Pernici, Process Track, Milano, April 2004


General architecture1
General Architecture execution plan are defined

Interaction Enabling

Platform

chooses the best n-ple for service

delivering

determines QoS levels acceptable for

the user

translates logical constraints

in technological ones

merges service/user/context constraints

(c) B. Pernici, Process Track, Milano, April 2004


General architecture2

First phase execution plan are defined

Second phase

General Architecture

Reflective Platform

Works on a given n-ple

Receives as input the acceptable

QoS levels with their constraints

Tries a channel adaptation making first

a theoretical adaptation study and then

trying to change the real values

Monitors the channel during

service provisioning

(c) B. Pernici, Process Track, Milano, April 2004


<abstractService name=“prenotazioneAerei”>

<minAffinityValue>0.7</minAffinityValue>

<qos>

<parameter>

<name>responseTime</name>

<minValue>5</minValue>

<maxValue>10</maxValue>

</parameter>

<parameter>

<name>localization</name>

<value>Italia</value>

</parameter>

</qos>

</abstractService>

(c) B. Pernici, Process Track, Milano, April 2004


Modeling qos
MODELING QoS execution plan are defined

(c) B. Pernici, Process Track, Milano, April 2004


Quality of service1
Quality of Service execution plan are defined

  • adaptation strategies

    • both the service and provider side

    • depend on the QoS definition

  • channel

    • deeply affects the values of the QoS parameters on the provider side

    • so the user can perceive different values according to the active channel

  • In a service oriented environment we have to consider all the involved actorsindependently

(c) B. Pernici, Process Track, Milano, April 2004


Our model
Our model execution plan are defined

  • Composed by:

    • A system model: objects and actors

    • A set of roles and rules

      • association of quality information to objects

      • relationships among them

  • Quality information expressed by:

    • Quality parameters

    • Quality sets

(c) B. Pernici, Process Track, Milano, April 2004


Objects and actors
Objects and actors execution plan are defined

  • Objects:

    • Services

    • Networks

    • Devices

  • Actors:

    • Service providers

    • Network providers

    • Device providers

    • Users

(c) B. Pernici, Process Track, Milano, April 2004


Objects and actors1
Objects and actors execution plan are defined

Service

providers

Network

providers

Users

Device

providers

Services

networks

devices

(c) B. Pernici, Process Track, Milano, April 2004


Communities
Communities execution plan are defined

  • A community exists for each object considered in the model:

    • A community for each type of service (VoD, hotel reservation, …)

    • A community for the network

    • A community for each type of device (PC, PDA, SmartPhone, …)

  • Given an object, the related community writes the specifications which define in an unambiguous way such an object

  • In our work we are interested in the quality specification of the object so the object specification is a set of quality parameters

(c) B. Pernici, Process Track, Milano, April 2004


Service community
Service Community execution plan are defined

Service

Provider B

Service

Provider A

ServiceCommunity

[email protected]

E-Video

Functional specification

&

  • Quality specification:

  • Framerate

  • Colordepth

  • Resolution

My-movie

Service

Provider C

(c) B. Pernici, Process Track, Milano, April 2004


Quality parameter
Quality parameter execution plan are defined

  • quality of objects

    • set of quality parameters

    • Defined by the community for that object

  • A quality parameter is a pair:

    • Name

    • Admissible_values

  • Examples of quality parameters:

    • <framerate, [5fps..40fps]>

    • <colordepth, [2bit..24 bit]>

    • <resolution, [320 × 200; 800 × 600; 1024 × 768]>

  • Functions best and worst are introduced to obtain the admissible value which correspond namely the best and the worst quality

    • More on going work on function definitions

(c) B. Pernici, Process Track, Milano, April 2004


Quality set
Quality set execution plan are defined

  • Quality Set: class of quality parameters identified by:

    • a name

    • a list of quality parameters belonging to such a set

  • Containment relationships QS1 QS2 holds iff:

    • same list of quality parameters

    • for each pair of quality parameters with the same name QS1_name.admissible_value  QS2_name.admissible_value

(c) B. Pernici, Process Track, Milano, April 2004


Roles for quality management
Roles for quality management execution plan are defined

  • Quality definition performed in two steps:

    • Specification definition phase: the community defines a quality set for the object specification

    • Object implementation phase: the provider operates a restriction on the specification quality parameters

  • Containment relationship between the object specification and implementation quality sets for an object:

    • QSobj QSspec

(c) B. Pernici, Process Track, Milano, April 2004


Model
Model execution plan are defined

(c) B. Pernici, Process Track, Milano, April 2004


Roles for quality management1
Roles for quality management execution plan are defined

  • We are interested in three main quality sets:

    • QoS: quality of service

    • QoN. quality of newtork

    • QoD: quality of device

  • For examples from the community specification we obtain the quality set QoSspec:

    • <framerate, [5fps..40fps]>

    • <colordepth, [2bit..24 bit]>

    • <resolution, [320×200; 800×600; 1024×768]>

  • From the service provider implementation the realized object is defined by the quality set QoSobj

    • <framerate, [5fps..30fps]>

    • <colordepth, [2bit..24 bit]>

    • <resolution, [320×200; 800×600]>

(c) B. Pernici, Process Track, Milano, April 2004


Quality of experience
Quality of Experience execution plan are defined

  • Represents the quality perceived by the user

  • Composed by the same quality parameters belonging to the QoS where the values are affected by the QoN, and QoD

QoN

QoD

Quality

rules

QoE

<framerate, [5fps..20fps]>

<colordepth, [2bit..16 bit]>

<resolution, [800×600]>

QoS

<framerate, [5fps..30fps]>

<colordepth, [2bit..24 bit]>

<resolution, [320×200; 800×600]>

(c) B. Pernici, Process Track, Milano, April 2004


Quality rules
Quality rules execution plan are defined

  • Quality rules are introduced to explicitly declare how the QoS is affected by the QoN and QoD

  • Given two quality sets QS1 and QS2 a quality rule is a function qr(QS1, QS2)= QS3, where:

    • QS3 is a quality set

    • QS3 QS1

  • Example of quality rule qr(QoS, QoN)=QoE:

    • framerate * colordepth * resolution = K * bandwidth

  • In this way we can state that:

(c) B. Pernici, Process Track, Milano, April 2004


Related work
Related work execution plan are defined

  • Quality of Service is a relevant topic for several researches area. In particular we analyzed:

    • Web Service community

    • Telecommunication community

    • Middleware community

  • In all of these efforts the definition of measurable characteristics of objects is fundamental

  • QoS are usually defined in a way that the are not fully under the control of the user

  • QoE highlights this difference and defines the subset of the QoS which is fully under control of the user

(c) B. Pernici, Process Track, Milano, April 2004



Classificazione delle variabili di qualit del servizio
Classificazione delle variabili di qualità del servizio rappresentazione

QoS

Dimensioni di qualità lato fornitore

Dimensioni di qualità negoziabili

Dimensioni di qualità intrinseche del servizio

Dimensioni di qualità relative a risorse per l’erogazione del servizio

Lato fornitore

Lato cliente

Caratteristiche

device

Profilo

utente

(c) B. Pernici, Process Track, Milano, April 2004


negoziazione interattiva o basata sul profilo utente rappresentazione

Negoziazione automatica

(c) B. Pernici, Process Track, Milano, April 2004


Esempi di dimensioni di qualit
Esempi di dimensioni di qualità rappresentazione

  • Esempi di dimensioni di qualità negoziabili lato fornitore sono:

    • Bandwith (Larghezza di banda)

    • Prezzo

    • Velocita'

    • Grado di sicurezza

    • Accuracy

    • Completeness

    • Adattività

    • Response time

    • Provisioning Time

    • Service Availability

    • Timeliness (Dati)

    • Availability (Dati)

(c) B. Pernici, Process Track, Milano, April 2004


Linguaggio di rappresentazione
Linguaggio di rappresentazione rappresentazione

  • Il linguaggio più completo per la rappresentazione delle caratteristiche di qualità è WSOL. Esso consente di specificare:

    • Vincoli funzionali (pre-condizioni, post-condizioni, e condizioni future)

    • Vincoli non funzionali (es. Vincoli di QoS)

    • Diritti di accesso

(c) B. Pernici, Process Track, Milano, April 2004


Linguaggio di rappresentazione1
Linguaggio di rappresentazione rappresentazione

  • Esempio di specifica QoS

    <wsol:offeringType name=“bookflight”

    service=“bookflight:bookflightService”

    ….

    <wsol:QoSconstraints name=“MaxResponseTime”

    <wsol:QoSname qname=“QoSns:responsetime”/>

    <wsol:QoStype typename=“QoSns:max”/>

    <wsol:qvalue> 50 </wsol:qvalue>

    <wsol:qunit unitname=“QoSns:ms”/>

    </wsol:QoSconstraints>

(c) B. Pernici, Process Track, Milano, April 2004


Estensioni al linguaggio
Estensioni al linguaggio rappresentazione

Estensioni del linguaggio che saranno apportate in MAIS:

  • Definizione dell’insieme delle dimensioni di QoS “MAIS”

  • Definizione dell’insieme delle specifiche di qualità “MAIS”

  • Introduzione di parametri importanti in fase di negoziazione (es. priorità sul soddisfacimento dei vincoli di qualità)

(c) B. Pernici, Process Track, Milano, April 2004


Conclusions and future work
Conclusions and future work rappresentazione

  • This work presents a way to define the quality information in a multichannel information system

  • All the involved actors can separately state the quality information for the controlled object

  • Quality rules are introduced in order to create a relationship among the quality information defined by the different actors

  • Now, analyzing some case studies we aim at finding other real quality rules

  • A prototype which exploit this model is under development

  • More theoretical work on:

    • Function definition

    • Dependency rules (ontology of quality dimensions) (OWL)

(c) B. Pernici, Process Track, Milano, April 2004


References
References rappresentazione

  • WSLA provides a framework to define the quality parameters, responsibilities about the monitoring, the agreement between service provider and requester

  • A. Mani and A. Magarajan, Understanding quality of service of your Web services, provides a list of useful parameters in Web Service context

  • L. Zeng et al. Quality driven web services composition. WWW 2003

  • Real-time CORBA enforce timeliness properties

  • Fault-tolerant CORBA (implemented in IRL) increasing the mean time to failure, to repair and thus between failures of CORBA objects through software replication techniques

  • DaQuinCIS project provides a set of data quality dimensions and infrastructure for their monitoring and improvement

  • Andrea Maurino, Stefano Modafferi, Barbara Pernici, Reflective architectures for adaptive information systems, ICSOC 2003:115-131

  • C. Marchetti, B. Pernici, P. Plebani,A Quality Model for Multichannel Adaptive Information Systems, WWW04 Conference, Alternate Track on Web Services, maggio 2004

(c) B. Pernici, Process Track, Milano, April 2004


References1
References rappresentazione

  • Carlo Marchetti, Barbara Pernici, Pierluigi Plebani, A quality model for e-Service based multi-channel adaptive information systems, WISE-WQW workshop, Dic. 2004

  • C. Cappiello, C. Francalanci, B. Pernici, Data quality assessment from a user perspective, Workshop SIGMOD-IQIS, giugno 2004

  • Carlo Marchetti, Barbara Pernici, Pierluigi Plebani, A Quality Model for Multichannel Adaptive Information Systems, WWW04 Alternate Track on Web Services, maggio 2004

(c) B. Pernici, Process Track, Milano, April 2004


ad