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from pilot searches we have done beforehand and
some papers provided by experts, which were
considered as “grey literature” in this SLR, as well
as other quality characteristics that in our opinion
can be relevant in this context. The alternative
spellings or terminology related to the major terms
are shown in Table 1.
Table 1: Search string.
Major terms
Alternative terms
Product line
Product families OR product family OR system
families OR system family OR product lines
Quality
Maintainability OR flexibility OR reusability OR
modifiability OR changeability OR functionality
OR usability OR efficiency OR portability OR
suitability OR accuracy OR interoperability OR
security OR “fault tolerance” OR recoverability
OR understandability OR comprehensibility OR
learnability OR operability OR attractiveness OR
“time behaviour” OR “resource utilisation” OR
analysability OR stability OR testability OR
adaptability OR installability OR replaceability
OR complexity OR extensibility OR scalability
OR customisability OR availability OR reliability
OR mobility OR integrability OR safety
Software -------
The relevant information from each paper used to
answer the main research question addressed by this
SLR was obtained from a data extraction strategy,
consisting of the following six criteria: Quality
characteristics, object of study, application domain,
type of proposal, research method and type of support.
2.2 Conducting the Review
Firstly, we found 319 papers. Afterward, we
analysed the title and abstract and selected 76 of
them. Finally, 43 papers were chosen as primary
studies, by applying the inclusion and exclusion
criteria. The classification of the 43 papers included
in this SLR can be found in http://alarcos.
esi.uclm.es/SLR-SPLquality.
3 RESULTS
In the following paragraphs we present an analysis of
the results obtained for each criterion used to extract
the relevant information from the 43 selected papers.
3.1 Quality Characteristics
At the beginning, in the planning of the review 37
quality characteristics were proposed, but only 15 of
these were found in the SLR. 11 other quality
characteristics were obtained in the SLR, but these had
not been proposed previously.
The final set of quality characteristics is the
following: functionality, reliability, usability,
efficiency, maintainability, portability, reusability,
effectiveness, availability, configurability, integrability,
scalability, modularity and applicability.
Regarding to the most important quality
characteristics in the context of SPLs, we shows that
maintainability and reusability are the most relevant
ones, followed by reliability, functionality,
portability and availability.
3.2 Object of Study
Various software artefacts were considered when we
were setting out to define or evaluate quality
characteristics in the context of SPLs. We looked at
software artefacts, i.e. software architecture of the
product line, software products obtained from SPLs
and Others. As (Bass et al., 1998) states, “software
architecture of the product line” is the structure or
structures of the system, which are composed of
software components, the externally visible properties
of those components, and the relationships between
them. A “software product obtained from SPLs”
studies the quality of the products obtained using the
SPL; “Others” includes the papers relating to core
assets, core asset requirements or product line
requirements.
3.3 Application Domain
The common domains are the embedded systems,
which can be found in telecommunications, the
automobile industry, electronic systems, medical
machines and so on. In our study, the most typical is
the telecommunications domain, with 11 papers. The
telecommunications domain is a set of
telecommunications functionalities, which in turn
consists of other domains, such as switching, protocols,
telephony and network. A telecommunications SPL is
a specific set of software systems that provides some
of these functionalities (Clements and Northrop,
2001).
The SPL domain that is in second place as regards
prevalence is the medical one, with 5 papers. In
addition, 3 papers have been classified as “general
product line” (i.e. they are not specific to a specific
domain, because the purpose was not really.
3.4 Type of Proposal
The type of proposals, that is, the type of techniques,
has been classified as:
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