1,721,002 research outputs found
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Understanding feature modularity
Get PDFtextFeatures are increments in program functionality. Feature abstraction, the process of
abstracting programs into their constituent features, is a relatively common yet informal
practice in software design. It is common because it simplifies program understanding. It
is also important for software product lines whose essence is the systematic and efficient
creation of software products from a shared set of assets or features, where each product
exhibits common functionality with other products but also has unique functionalities.
Thus, it seems natural to modularize feature abstractions and use such modules as
building blocks of programs and product lines. Unfortunately, conventional modularization
approaches such as methods, classes and packages are not geared for supporting feature
modules. They present two recurrent problems. First, a typical feature implementation
is spread over several conventional modules. Second, features are usually more than
source code artifacts as they can modularize many different program representations
(makefiles, documentation, performance models).
An undesirable consequence is that developers must lower their abstractions from
features to those provided by the underlying implementation languages, a process that is
far from simple let alone amenable to significant automation. The conceptual gap created
between feature abstractions and their modularization hinders program understanding and
product line development. The root of the problem is the fact that feature modularity is not
well understood and thus not well supported in conventional programming languages,
modularization mechanisms, and design techniques.
In this dissertation, we explore language and modularity support for features
founded on an algebraic model geared for program synthesis. Our model integrates ideas
from collaboration-based designs, mixin layers, aspect oriented programming, multidimensional
separation of concerns, and generative programming. We assess our model
with an implementation of a non-trivial product line case study, and evaluate feature support
in emerging modularization technologies.Computer Scienc
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Design and analysis of multidimensional program structures
No full textSoftware design is an art. More often than not, designers rely on craftsmanship and creativity for designing software products. Just as understanding of the structure of atomic elements is critical to the natural sciences, it too is fundamental to the science behind software engineering. Structural theories simplify our understanding of a convoluted mechanism and allow us to reason in a clear and concise manner. Therefore, decision making can transcend subjective justification and move to quantitative and precise reasoning. Feature-Oriented Programming and compositional programming embody ideas of software decomposition structure. Feature-Oriented Programming treats Features as the building-blocks that are composed to synthesize programs. Its convergence with algebraic transformations has led to AHEAD - a simple algebraic model of Feature-Oriented Programming. Within AHEAD, reasoning over simple algebraic structures enables codification and mechanization of well-understood principles. In this thesis we demonstrate just that by showing that critical properties of a decomposition can be identified and verified efficiently. First, we introduce multidimensional structures, a higher-order structural relationship within conventional decomposition. Multidimensional structures simplify a complex decomposition’s representation, understanding, and compositional specification. However, not all decompositions are fit for a multidimensional arrangement. We identify an essential property of orthogonality that a decomposition and its implementation must satisfy in order to warrant a multidimensional structure. Next, we identify a class of errors that occur at module composition-time. These composition errors are a result of unsatisfied dependencies when feature modules are composed in arbitrary arrangements. AHEAD introduces architectural-level domain constraints that govern the compatibility of feature modules. Besides architectural-level composition constraints, there are also low-level implementation constraints: a feature module can reference classes that are defined in other feature modules. Safe composition is the guarantee that programs composed from feature modules are absent of references to undefined classes, methods, and variables. We show how safe composition can be guaranteed for AHEAD product lines using feature models and SAT solvers. The significance of this work lies in the generality of our approach. Multidimensional structures are not unique to AHEAD; we demonstrate its applicability under any form of decomposition. Likewise, safe composition also extends AHEAD. We draw an analogy between safe composition and C++ linking errors. Moreover, we demonstrate how non-code artifacts benefit from modularization as well as safe composition analysis. In identifying and verifying key properties, we have also demonstrated how the structural model of AHEAD can simplify our understanding and applicability of essential principles. When the fundamental structure is well-understood, software design is amenable to automation.Computer Scienc
Static meta-object protocols: towards efficient reflective object-oriented languages
No full textReflection and extensibility in object-oriented programming languages can be supported by meta-object protocols (MOP) that define class-based interfaces over data representation and execution features. MOPs are typically dynamic in the sense that type-based dispatching is used to select between feature implementations at run time leading to a significant difference in execution speed compared to non-MOP-based languages. Defining a corresponding static-MOP would seem to be a solution whereby type-dispatching can occur at compile time. Such an approach requires the integration of a static type system with a MOP. This paper introduces a new reflective and extensible language called JMF written in Java that aims to generate efficient code through the use of a static-MOP. The contribution of this paper is to characterise a static-MOP and to show how it integrates with a type system for JMF
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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Systematic techniques for efficiently checking Software Product Lines
Get PDFtextA Software Product Line (SPL) is a family of related programs, which of each is defined by a combination of
features. By developing related programs together, an SPL simultaneously reduces programming effort and satisfies multiple sets of requirements. Testing an SPL efficiently is challenging because a property must be checked for all the programs in the SPL, the number of which can be exponential in the number of features.
In this dissertation, we present a suite of complementary static and dynamic techniques for efficient testing and runtime monitoring of SPLs, which can be divided into two categories. The first prunes programs, termed configurations, that are irrelevant to the property being tested. More specifically, for a given test, a static analysis identifies features that can influence the test outcome, so that the test needs to be run only on programs that include these features. A dynamic analysis counterpart also eliminates configurations that do not have to be tested, but does so by checking a simpler property and can be faster and more scalable. In addition, for runtime monitoring,
a static analysis identifies configurations that can violate a safety property and only these configurations need to be monitored.
When no configurations can be pruned, either by design of the test or due to ineffectiveness of program analyses,
runtime similarity between configurations, arising due to design similarity between configurations of a product line, is exploited. In particular, shared execution runs all the configurations together, executing bytecode instructions common to the configurations just once. Deferred execution improves on shared execution by
allowing multiple memory locations to be treated as a single memory location, which can increase the amount of sharing for object-oriented programs and for programs
using arrays.
The techniques have been evaluated and the results demonstrate that the techniques can be effective and can advance the idea that despite the feature combinatorics of an SPL, its structure can be exploited by automated analyses to make testing more efficient.Computer Scienc
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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