Environmental Engineering Reference
In-Depth Information
metrics corresponding to them describe the pro-
gramming product that is completed and ready
for use. In order to evaluate software quality the
standard (ISO, 1999) defines six groups of external
and internal characteristics.
d. Reliability compliance is the degree of
software conformity to normative require-
ments for reliability (standards), and also to
customer requirements.
The basic nomenclature, calculation sequence
and scale of possible values for metrics of soft-
ware quality that pertain to each group of quality
products with reference to the lifecycle process
in which the metric is used, and composition of
the necessary documentation for determining
input parameters for calculation are defined in
(ISO, 2000).
In addition to the listed categories the standard
(IEEE, 1988, a) determines a number of functional
groups that characterize different properties of
reliability of the software itself (indicators, or
product measures), as well as the design process
(process metrics), based on which the reliability
metrics are classified.
Examined standards can be used to create
profiles of the evaluation and quality assurance
of software. Figure 5 shows the interconnection
of the standards IEEE 982.1-1988 (IEEE, 1988,
a) and ISO/IEC 9126-1:1999 (ISO, 1999). The
standard ISO/IEC 9126-1:1999 is fundamental
and assures comprehensive inclusion of software
quality. At the same time the standard IEEE 982.1-
1988 allows one to assure more thorough analysis
of software reliability as one of the top priority
quality characteristics of software of information
and control critical systems.
Based on an analysis of the classifications
presented above for the systematic description of
quality metrics and reliability a unified system of
classification features is proposed (Figure 6).
Development of the systemic classification of
reliability metrics and software quality is a neces-
sary condition of successful harmonization of
normative documents and creation of effective
methods of evaluation and assurance of quality
of the software being developed.
Production and analysis of initial information
for determining metrics:
Analysis of the standards
1. Functionality is a set of software properties
that determines its ability to execute the
established functions.
2. Reliability is the set of properties that enable
the software to retain its serviceability and to
convert raw data into the desired result under
predetermined conditions in an established
period of time.
3. Usability is the set of properties that charac-
terizes the necessary conditions of software
use by users.
4. Efficiency is the set of properties that charac-
terizes conformity of the software resources
used to quality of execution of its functions.
5. Maintainability is the set of properties that
characterizes the level of efforts needed to
execute the required software modifications.
6. Portability is the set of properties that char-
acterizes the adaptability of software to work
in different functional environments.
The set of metrics that pertain to each group of
higher level characteristics is again divided into
several sub-characteristics. For example, the soft-
ware reliability, which is defined as the capability
of software to maintain its level of performance
under stated conditions for a stated period of time,
includes the following sub-characteristics:
a. Maturity is the set of indicators that describe
frequency of occurrence remaining in the
software.
b. Fault tolerance is the ability of software to
retain a certain functioning level during the
onset of software malfunctions.
c. Recoverability is the property of software
to restore its ability to work (assigned level
of functioning), and also program data.
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