Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: theorem proving; modular verification; software verification; feature-oriented programming; feature interaction. Includes bibliographical references (p. 131-136).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: modular verification; feature-oriented software development; model checking; assume-guarantee reasoning. Includes bibliographical references (p. 72-73).

"Feature-oriented programming is a way of designing a program around the features it performs, rather than the objects or files it manipulates. This should lead to an extensible and flexible "product-line" architecture that allows custom systems to be assembled with particular features included or excluded as needed. Composing these features together modularly, while leading to flexibility in the feature-set of the finished product, can also lead to unexpected interactions that occur between features. Robert Hall presented a manual methodology for locating these interactions and has used it to search for feature interactions in email. Li et al. performed automatic verification of Hall's system using model-checking verifications tools. Model-checking verification is state-based, and is not well-suited for verifying recursive data structures, an area where theorem-proving verification tools excel. In this thesis, we propose a methodology for using formal theorem-proving tools for modularly verifying feature-oriented systems. The methodology presented captures the essential steps for using modular techniques for modeling and verifying a system. This enables verification of individual modules, without examining the source code of the other modules in the system. We have used Hall's email system as a test case for validating the methodology."

A 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. / text

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media

"The essence of software design is to construct well-defined, encapsulated modules that are composed together to build the desired software application. There are several design paradigms in use today, including traditional Object-Oriented Programming (OOP), Feature-Oriented Programming (FOP), Aspect-Oriented Programming (AOP) and Instance-Oriented Programming (IOP). FOP studies the modularity of features in product lines, where a feature is an increment in program functionality. AOP aims to separate and modularize aspects when an aspect is a crosscutting concern. IOP, as an extension to FOP, makes the layers work like object factories. While each is good at solving different types of problems, they are closely related. The composition of modules is complicated because modules have (often hidden) dependencies on other modules. This thesis aims to better understand the way dependencies are managed by each approach. Based on this, we focus on the precedence issue in AOP and FOP, that is, how designers are able to specify the order by which modules are composed together. Different precedence means different semantics, but the current tools can not guarantee the correct precedence is adopted. We first solve the precedence issue separately for AOP and FOP, then based on this, we come up with a unified model to solve the precedence issue by using source code annotations to specify the precedence. We evaluate our technique with use cases. "

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media

Background: A key idea of feature orientation is to decompose a software product line along the features it provides. Feature decomposition is orthogonal to object-oriented decomposition it crosscuts the underlying package and class structure. It has been argued often that feature decomposition improves system structure (reduced coupling, increased cohesion). However, recent empirical findings suggest that this is not necessarily the case, which is the motivation for our empirical investigation. Aim: In fact, there is little empirical evidence on how the alternative decompositions of feature orientation and object orientation compare to each other in terms of their association with observable properties of system structure (coupling, cohesion). This motivated us to empirically investigate and compare the properties of three decompositions (object-oriented, feature-oriented, and their intersection) of 28 feature-oriented software product lines. Method: In an exploratory, observational study, we quantify internal attributes, such as import coupling and cohesion, to describe and analyze the different decompositions of a feature-oriented product line in a systematic, reproducible, and comparable manner. For this purpose, we use three established software measures (CBU, IUD, EUD) as well as standard distribution statistics (e.g., Gini coefficient). Results: First, feature decomposition is associated with higher levels of structural coupling in a product line than a decomposition into classes. Second, although coupling is concentrated in feature decompositions, there are not necessarily hot-spot features. Third, the cohesion of feature modules is not necessarily higher than class cohesion, whereas feature modules serve more dependencies internally than classes. Fourth, coupling and cohesion measurement show potential for sampling optimization in complex static and dynamic product-line analyses (product-line type checking, feature-interaction detection). Conclusions: Our empirical study raises critical questions about alleged advantages of feature decomposition. At the same time, we demonstrate how the measurement of structural attributes can facilitate static and dynamic analyses of software product lines. (authors' abstract) / Series: Technical Reports / Institute for Information Systems and New Media

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: conflict; precedence; dependency; feature-oriented programming; object-oriented design; aspect-oriented programming. Includes bibliographical references (p.76-78).

Feature-oriented software architecture is a way of organizing code around the features that the program provides instead of the program's objects and components. In the development of a feature-oriented software system, the developers, supplied with a set of features, select and organize features to construct the desired system. This approach, by better aligning the implementation of a system with the external view of users, is believed to have many potential benefits such as feature reuse and easy maintenance. However, there are challenges in the formal verification of feature-oriented systems: first, the product may grow very large and complicated. As a result, it's intractable to apply the traditional formal verification techniques such as model checking on such systems directly; second, since the number of feature-oriented products the developers can build is exponential in the number of features available, there may be redundant verification work if doing verification on each product. For example, developers may have shared specifications on different products built from the same set of features and hence doing verification on these features many times is really unnecessary. All these drive the need for modular verifications for feature-oriented architectures. Assume-guarantee reasoning as a modular verification technique is believed to be an effective solution. In this thesis, I compare two verification methods of this category on feature-oriented systems and analyze the results. Based on their pros and cons, I propose a new modular model checking method to accomplish verification for sequential feature compositions with cyclic connections between the features. This method first builds an abstract finite state machine, which summarizes the information related to checking the property/specification from the concrete feature design, and then applies a revised CTL model checker to decide whether the system design can preserve the property or not. Proofs of the soundness of my method are also given in this thesis.