An Approach of Concurrent Object-Oriented Program Slicing Based on LTL Property

In this paper we provide a notion of causality for the violation of general Linear Temporal Logic (LTL) properties. The current work is a natural extension of the previously proposed approach handling causality in the context of LTL-definable safety properties. The major difference is that now, counterexamples of general LTL properties are not merely finite traces, but infinite lasso-shaped traces. We analyze such infinite counterexamples and identify the relevant ordered occurrences of causal events, obtained by unfolding the looping part of the lasso shaped counterexample sufficiently many times. The focus is on LTL properties from practical considerations: the current results are to be implemented in QuantUM, a tool for causality checking, that exploits explicit state LTL model checking.

With the enhancement of hardware and software engineering, the effectiveness and correctness of software is less and less doubted and customers are more aware about whether software services are available or not when needed. Software maintenance is one of the main reasons that make software unavailable and it is often very expensive to perform maintenance tasks. Common approaches of studying software maintenance are to consider it as a static by‐product of software operation and only the maintenance cost is covered. In this paper, software maintenance policies are studied with the consideration of unavailable service time. A non‐homogeneous continuous Markov chain is adopted for modeling the software operation and maintenance process, and the cost of software unavailability that is brought in by software maintenance is investigated and analyzed for searching the optimal maintenance policy, which aims at minimizing the average maintenance time cost. The optimality of our proposed policy is shown and checked by numerical examples with discussions of its possible application perspectives. Copyright © 2010 John Wiley & Sons, Ltd.

Nowadays systematic verification is essential because embedded systems are involved in processes decisions that affect the life of humans and they are subject to several constraints in interaction with dangerous processes. To ensure the proper functioning of these systems and reduce the degree of failure of an internal part and the time to market, we opt for formal method of verification which deals particularly with Model-Checking model verification by implementing our new verification platform SysVerPml that uses protocol models written in Promela language (PROcess Meta LAnguage) and integrating generic properties in LTL (Linear Temporal Logic) that can be simulated and verified by the Spin software and its Ispin GUI to detect all the possibilities of error. Until now, there have been few research papers directed towards converting SystemC models to Promela language, and until today there is no free platform that is dedicated to this verification process.

During software development and maintenance, developers spend a considerable amount of time on program comprehension activities. Previous studies show that program comprehension takes up as much as half of a developer’s time. However, most of these studies are performed in a controlled setting, or with a small number of participants, and investigate the program comprehension activities only within the IDEs. However, developers’ program comprehension activities go well beyond their IDE interactions. In this paper, we extend our ActivitySpace framework to collect and analyze Human-Computer Interaction (HCI) data across many applications (not just the IDEs). We follow Minelli et al.’s approach to assign developers’ activities into four categories: navigation, editing, comprehension, and other. We then measure the comprehension time by calculating the time that developers spend on program comprehension, e.g., inspecting console and breakpoints in IDE, or reading and understanding tutorials in web browsers. Using this approach, we can perform a more realistic investigation of program comprehension activities, through a field study of program comprehension in practice across a total of seven real projects, on 78 professional developers, and amounting to 3,148 working hours. Our study leverages interaction data that is collected across many applications by the developers. Our study finds that on average developers spend $\sim$ 58 percent of their time on program comprehension activities, and that they frequently use web browsers and document editors to perform program comprehension activities. We also investigate the impact of programming language, developers’ experience, and project phase on the time that is spent on program comprehension, and we find senior developers spend significantly less percentages of time on program comprehension than junior developers. Our study also highlights the importance of several research directions needed to reduce program comprehension time, e.g., building automatic detection and improvement of low quality code and documentation, construction of software-engineering-specific search engines, designing better IDEs that help developers navigate code and browse information more efficiently, etc.

Dataflow languages are widely used for programming real-time embedded systems. They offer high level abstraction above hardware, and are amenable to program analysis and optimisation. This paper addresses the challenge of verifying parallel program transformations in the context of dynamic dataflow models, where the scheduling behaviour and the amount of data each actor computes may depend on values only known at runtime. We present a Linear Temporal Logic (LTL) model checking approach to verify a dataflow program transformation, using three LTL properties to identify cyclostatic actors in dynamic dataflow programs. The workflow abstracts dataflow actor code to Fiacre specifications to search for counterexamples of the LTL properties using the Tina model checker. We also present a new refactoring tool for the Orcc dataflow programming environment, which applies the parallelising transformation to cyclostatic actors. Parallel refactoring using verified transformations speedily improves FPGA performance, e.g.15.4 × speedup with 16 actors.

Recovering design pattern instances in a software system can help maintainers to understand its design and implementation. In this paper we present a fully automated design pattern recovery approach that analyzes the behavior of pattern instances both statically and dynamically. In particular, the proposed approach exploits model checking to statically verify the behavioral aspects of design pattern instances. To this end, we encode the properties defining the correct behavior of a pattern as LTL (Linear Temporal Logic) formulae and the sequence diagram representing the possible interaction traces among the objects involved in the candidate instances as PROMELA specifications. To verify whether the LTL properties are satisfied by the candidates we employ the SPIN model checking tool. The dynamic analysis of the pattern behavior is performed through a code instrumentation and monitoring phase applied on the candidate pattern instances. This phase allows us to obtain actual dynamic data during program execution, which is then used to verify its compliance to the pattern definition. The effectiveness of the proposed approach is shown by presenting and discussing the results obtained on JHotDraw and JRefactory.

During software development and maintenance, developers spend a considerable amount of time on program comprehension. Previous studies show that program comprehension takes up as much as half of a developer's time. However, most of these studies are performed in a controlled setting, or with a small number of participants, and investigate the program comprehension activities only within the IDEs. However, developers' program comprehension activities go well beyond their IDE interactions.

Program slicing is a method for automatical program decomposition. This paper presents an improved slicing algorithm on the basis of static analysis of the control structure of loop statements. The slice obtained by the new algorithm is guaranteed to be no larger than that obtained by the previous slicing algorithm developed by Mark Weiser. Moreover, the former will be much smaller than the latter for certain kinds of programs. In addition, a brief discussion of using slicing in program verification has been given for the sake of extending the application area of program slicing.

Program Slicing is a popular technique that assists in various software maintenance activities like debugging, program comprehension and regression testing. It is a decomposition technique used for the extraction of program statements affecting the values computed at some point of interest. We propose a technique for computing slices of XML documents. Given a valid XML document, we produce a new XML document (a slice) containing the relevant information in the original XML document according to some criterion. We output a new DTD such that the computed slice is valid with respect to this DTD. Our technique first slices the associated DTD and the DTD slice is used as a slicing criterion in order to produce the associated XML slice.KeywordsTag dependence graph (TDG)Extensible Markup Language(XML)Document Type Definition (DTD)

Software reliability

Developers spend a substantial amount of their time with program comprehension. To improve their comprehension and refresh their memory, developers need to communicate with other developers, read the documentation, and analyze the source code. Many studies show that developers focus primarily on the source code and that small improvements can have a strong impact. As such, it is crucial to bring the code itself into a more comprehensible form. A particular technique for this purpose are explicit feature traces to easily identify a program’s functionalities. To improve our empirical understanding about the effects of feature traces, we report an online experiment with 49 professional software developers. We studied the impact of explicit feature traces, namely annotations and decomposition, on program comprehension and compared them to the same code without traces. Besides this experiment, we also asked our participants about their opinions in order to combine quantitative and qualitative data. Our results indicate that, as opposed to purely object-oriented code: (1) annotations can have positive effects on program comprehension; (2) decomposition can have a negative impact on bug localization; and (3) our participants perceive both techniques as beneficial. Moreover, none of the three code versions yields significant improvements on task completion time. Overall, our results indicate that lightweight traceability, such as using annotations, provides immediate benefits to developers during software development and maintenance without extensive training or tooling; and can improve current industrial practices that rely on heavyweight traceability tools (e.g., DOORS) and retroactive fulfillment of standards (e.g., ISO-26262, DO-178B).

Program comprehension is an important task faced by developers during software maintenance. With the increasing complexity of evolving systems, program comprehension becomes more and more difficult. In practice, programmers are accustomed to getting a general view of the features in a software system and then finding the interesting or necessary files to start the understanding process. Given a system, developers may need a general view of the system. The traditional view of a system is shown in a package-class structure which is difficult to understand, especially for large systems. In this article, we focus on understanding the system in both feature view and file structure view. This article proposes an approach to generate a feature tree based on hierarchical Latent Dirichlet Allocation (hLDA), which includes two hierarchies, the feature hierarchy and file structure hierarchy. The feature hierarchy shows the features from abstract level to detailed level, while the file structure hierarchy shows the classes from whole to part. Empirical results show that the feature tree can produce a view for the features and files, and the clustering of classes in the package in our approach is better (in terms of recall) than the other clustering approach, that is, hierarchical clustering.

Program comprehension is one of the most frequently performed activities during software maintenance and evolution. In order to facilitate program comprehension, a variety of graphical models have been proposed in software engineering community to construct relationships between program elements. These graphical models are mostly used for understanding the system based on structural syntax dependencies between program elements. However, these graphical models fail to extract the functional or semantic features of the system. Thus, developers still cannot effectively identify the functional part in source code fit for their needs. This paper tries to fill this gap, and proposes a novel representation, program feature network (PFN), to identify the semantic features of the program at class level. PFN is generated based on the relational topic model, a hierarchical probabilistic model of networks. Based on PFN, the semantic features and the links between pairs of two classes in the program can be clearly shown. In addition, PFN can predict the possible links between the newly change request in existing program feature network rather than reconstructing the representation from the start.

Program comprehension is an important activity in software maintenance, as software must be sufficiently understood before it can be properly modified. The study of a program's execution, known as dynamic analysis, has become a common technique in this respect and has received substantial attention from the research community, particularly over the last decade. These efforts have resulted in a large research body of which currently there exists no comprehensive overview. This paper reports on a systematic literature survey aimed at the identification and structuring of research on program comprehension through dynamic analysis. From a research body consisting of 4,795 articles published in 14 relevant venues between July 1999 and June 2008 and the references therein, we have systematically selected 176 articles and characterized them in terms of four main facets: activity, target, method, and evaluation. The resulting overview offers insight in what constitutes the main contributions of the field, supports the task of identifying gaps and opportunities, and has motivated our discussion of several important research directions that merit additional consideration in the near future.

Most of today's industries, from engineering to agriculture to health, are run on software. In such a context, ensuring software quality play an important role in most of current working environment and have a direct impact in any scientific and technical discipline. Software maintenance and testing have the crucial goal to find or discover possible software bugs (or defects) as early as possible, enabling software quality assurance. However, software maintenance and testing are very expensive and time-consuming activities for developers. For this reason, in the last years, several researchers in the field of Software Engineering (SE) devoted their effort in conceiving tools for boosting developers productivity during such development, maintenance and testing tasks. In this talk, I will first discuss some empirical work we performed to understand the main socio-technical challenges developers face when joining a new software project. I will discuss how to address them with the use of appropriate recommender systems aimed at supporting developers during program comprehension and maintenance tasks. Then, I'll show how Summarization Techniques are an ideal technology for supporting developers when performing testing and debugging activities. Finally, I will summarize the main research advances, the current open challenges/problems and possible future directions to exploit for boosting developers productivity.