1,720,962 research outputs found
Detecting and resolving semantic pathologies in UML sequence diagrams
No full textScenario based requirements specifications are the industry norm for defining communicating systems. These scenarios are often captured in the form of UML/MSC sequence diagrams. Errors are often introduced at this stage of the development process, which are costly to resolve if they are not detected early. This paper is concerned with the automatic detection and resolution of semantic errors that can occur in such scenarios.The paper discusses a semantic interpretation of scenario-based requirements and various types of defects (or pathologies) that can be detected. The paper defines the semantics and defects within a partial order theoretic framework. We introduce a UML 2.0 profile that captures various domain specific communication semantics, which can be used to determine the relevance of detected pathologies when different underlying implementation assumptions are made. The paper also discusses how to automatically resolve pathologies by using this profile to adapt the communication architecture in the requirements model
Scenario Synthesis from Imprecise Requirements
No full textDiscovering faults in requirements specifications for distributed reactive systems is a challenging problem since many issues that need to be uncovered are a result of subtle component interactions that are implied by the requirements, but not explicitly described by them. A further difficulty is caused by the imprecise nature of industrial requirements specifications. This makes it difficult to construct valid models of the possible compositions between the requirements, which would be a valuable aid in uncovering such interactions. The paper defines a formal semantics that characterizes a particular type of imprecise compositional semantics derived from industrial case studies, and a process algebra that describes the valid requirements compositions for that formal semantics
Cutting and Pasting with Requirements Specifications Scenarios
No full textWireless Telecommunications requirements specifications tend to be defined as sets of normative scenarios. These frequently only provide partial coverage of the scenarios that are necessary to give a comprehensive specification. Standard model checking techniques have not been successful in analysing such protocol specifications, first because of the high degree of concurrency that is inherent in such systems, and secondly because the very partial nature of the specifications tends to cause many inconsequential defects to be reported that frustrate the process of identifying key issues that have to be addressed immediately. Typically the inconsequential defects are addressed by adding new scenarios to the requirements, whereas significant defects require structural changes to the design itself and are not solved by adding new scenarios. This paper describes a technique for synthesising tractable phase automata from Message Sequence Chart scenarios that describe major phase transitions in the specifications. These can be automatically analysed to detect certain types of significant interactions between the scenarios that will be invariant under the addition of new scenarios to the requirements specifications
Requirements-Based Test Generation: An Industrial Perspective
No full textThis paper discusses our experience with the deployment of requirements-based test generation within a large industrial setting. In doing so, we present an overview of our technologies and changes to the technical approach needed to aid deployment, especially the introduction of requirements validation
Characterizing Communication Channel Deadlocks in Sequence Diagrams
No full textUML sequence diagrams (SDs) are a mainstay of requirements specifications for communication protocols. Mauw and Reniers' algebraic (MRA) semantics formally specifies a behaviour for these SDs that guarantees deadlock free processes. Practitioners commonly use communication semantics that differ from MRA, which may result in deadlocks. For example FIFO, token ring, etc. We define a process algebra that is an extension of the MRA semantics for regular sequence diagrams. Our algebra can describe several commonly used communication semantics. Regular SDs are constructed from concurrent message flows via iteration, branching, and sequential composition. Their behaviour is defined in terms of a set of partial orders on the events in the SD. Such partial orders are known as causal orders. We define partial order theoretic properties of a causal order that are particular kinds of race condition. We prove any of the common communication semantics we list either guarantees deadlock free SDs or can result in a deadlock if and only if a causal order of an SD contains one of these types of race condition. This describes a complete classification of deadlocks as specific types of race condition
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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