Quality of Service: Concept Analysis

Report
Quality of Service: Concept Analysis
Jolanta Miliauskaitė
Vilnius University
Institute of Mathematics and Informatics
Content
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Introduction
What is the Quality?
What means the Quality of Service?
Conclusions
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Introduction
• quality-driven composition of semantic
web services
• domain-independent characteristics of
quality
• highly dynamic environment
• ontological model
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What is the Quality?
• The five different meanings of the term
quality:
 Transcendental (or metaphysical) view
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Product-Based View
User-Based View
Manufacturing-Based View
Value-Based View
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What is the Quality?
 Transcendental (or metaphysical) view
• “innate excellence”
• absolute and universally recognizable, a mark of
uncompromising standards and high achievement
• an ideal, towards which we should strive but
which can never be achieved in objective reality
• cannot be measured by experts and can be
perceived through experience alone
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What is the Quality?
 Product-Based View
• quantifiable and measurable characteristics
or attributes
 it examines the quality from inside perspective
and assumes that a product which has good
internal properties has also good external
properties
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What is the Quality?
 Product-Based View
• ISO-9004 standard
 quality is defined as
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fitness for use
performance
safety
dependability
 quality of design
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What is the Quality?
 Product-Based View
 The disadvantages of this approach
 it do not take into account preferences of a
particular user
 it assumes that the absence or presence of an
attribute implies higher quality
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What is the Quality?
 User-Based View
• fitness for purpose
• market-place quality or consumer preference
• Idea - quality is an individual matter, and things
that best satisfy user preferences have the highest
quality
• context-dependent
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What is the Quality?
 User-Based View
• highly subjective
• product characteristics as
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usability
reliability
performance
efficiency
• Product is of high quality if it satisfies a large
number of users
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What is the Quality?
 User-Based View
• how to sum up varying individual preferences of
particular users
• how to know which attributes are for quality and
which for user satisfaction
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What is the Quality?
 User-Based View
• difficult to develop
• user’s satisfaction may change
• large number of non-quality issues
• function of the differences between customer’s
expectation and performance along the quality
dimensions
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What is the Quality?
 Manufacturing-Based View
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conformance to requirements specification in which the
requirements are stated mostly in technical terms
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idea - any deviation from the specification decreases
quality
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objective and measurable terms
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focuses on making error-free products or services
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not on the absence or presence of some attributes
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What is the Quality?
 Manufacturing-Based View
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quality of conformance
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errors can be eliminated by
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conformance to process standards
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concentrates on engineering
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manufacturing practices
It is supported by ISO 9001 standard and CMM.
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What is the Quality?
 Value-Based View
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the degree of excellence at an acceptable price
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it makes a trade-off between cost and quality
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the Value-Based View (in the context of web
services)
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cost
functionality
time to deliver
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What is the Quality?
 Summary
• The concept of quality has
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multiple definitions
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wide variety of phenomena
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context dependent and time period
dependent
• unique ontological model
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What means the Quality of Service?
• services and products share many similarities,
they differ also in a number of ways
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intangibility
heterogeneity
inseparability
Perishability
• Conflicting opinions exist on these issues.
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What means the Quality of Service?
• SQuaRE model for software
• Ability to provide specific users with specific
service in defined context of use (user-based
view of quality)
• propose to consider also internal web service
quality (manufacturing-based view of quality)
• external web service quality (product-based
view of quality)
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Conclusions
• ambiguous and difficult to define precisely
• although observations are very significant and
highlight some aspects of the nature of this
concept, unfortunately,
• they are still not enough to develop the
ontological model of QoS
• more deep analysis of QoS should be done for this
aim
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Thank you for your attention
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