1,720,981 research outputs found
A Formally Grounded Software Specification Method
No full textOne of the goals of software engineering is to provide what is necessary to write relevant, legible, useful descriptions of the systems to be developed, which will be the basis of successful developments. This goal was addressed both from informal approaches (providing in particular visual notations) and formal ones (providing
a formal sound semantic basis). Informal approaches are often driven by a software development method, and, while formal approaches sometimes provide a user
method, it is usually aimed at helping to use the proposed formalism when writing a specification. Our goal here is to provide a companion method that helps the user
to understand the system to be developed, and to write the corresponding formal specifications. We also aim at supporting visual presentations of formal specifications, so as to “make the best of both formal and informal worlds”.
We developed this method for the (logical-algebraic) specification languages Casl (Common Algebraic Specification Language, developed within the joint initiative CoFI) and for an extension for dynamic systems Casl-Ltl, and we believe it is general enough to
be adapted to other paradigms.
Another challenge is that a method that is too general does not encompass the different kinds of systems to be studied, while too many different specialized methods result in partial views that may be difficult to integrate in a single global one. We deal with this issue by providing a limited number of instances of our method, fitted for three different kinds of software items, while keeping a common “meta”- structure and way of thinking. More precisely, we consider here that a software item
may be a simple dynamic system, a structured dynamic system, or a data structure, and we show here how to support property-oriented (axiomatic) specifications. We
are thus providing support for the “building-bricks” tasks of specifying software artifacts that in our experience are needed for the development process.
Our approach is illustrated with a lift case study
A UML-Based Approach for Problem Frame Oriented Software Development
No full textWe propose a software development approach that combines the use of the structuring concepts provided by problem frames, the use of the UML notation, together with our methodological approach for well-founded methods. Problem frames are used to provide a first idea of the main elements of the problem under study. Then we provide ad hoc UML based development methods for some of the most relevant problem frames together with precise guidelines for the users. The general idea of our method is that, for each frame, several artifacts have to be produced, each one corresponding to a part of the frame. The description level may range from informal and sketchy, to formal and precise, while this approach is drawn from experience in formal specifications.
Thus we show how problem frames may be used upstream of a development method to yield an improved and more efficient method equipped with the problem frames structuring concepts
Using CASL to Specify the Requirements and the Design: A Problem Specific Approach
No full textIn [11] M. Jackson introduces the concept of problem frame to describe specific classes of problems, to help in the specification and design of systems, and also to provide a framework for reusability. He thus identifies some particular frames, such as the translation frame (e.g., a compiler), the information system frame, the control frame (or reactive system frame), . . . . Each frame is described along three viewpoints that are application domains, requirements, and design.
Our aim is to use Casl (or possibly a sublanguage or an extension of Casl if and when appropriate) to formally specify the requirements and the design of particular classes of problems (“problem frames”). This goal is related to methodology issues for Casl, that are here addressed in a more specific way, having in mind some particular problem frame, i.e., a class of systems.
It is hoped that this will provide both a help in using, in a really effective way, Casl for system specifications, a link with approaches that are currently used in the industry, and a framework for the reusability. This approach is illustrated with some case studies, e.g., the information system frame is illustrated with the invoice system
Activity Diagrams Patterns for Modeling Business Processes
No full textDesigning and analyzing business processes is the starting point of the development of enterprise applications, especially when following the SOA (Service Oriented Architecture) paradigm. UML activity diagrams are often used to model business processes. Unfortunately, their rich syntax favors mistakes by designers; furthermore, their informal semantics prevents the use of automated verification
techniques. In this paper, (i) we propose activity diagram patterns for modeling business processes, (ii) we devise a modular mechanism to compose diagram fragments into a UML activity diagram, and (iii) we propose a semantics for the produced activity diagrams, formalized by colored Petri nets. Our approach guides the modeler task (helping to avoid common mistakes), and allows for automated verification
Casl-Mdl, Modelling Dynamic Systems with a Formal Foundation and a UML-Like Notation
No full textIn this paper we present a part of Casl-Mdl, a visual modelling notation based on Casl-Ltl (an extension for dynamic system of the algebraic specification language Casl). The visual constructs of Casl-Mdl have been borrowed from the UML, thus existing editors may be used. A Casl-Mdl model is a set of diagrams but it corresponds to a Casl-Ltl specification, thus Casl-Mdl is a suitable means to easily read and write large and complex Casl-Ltl specifications. We use as a running example a case study that describes the functioning of a consortium of associations
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
Analysing UML Active Classes and Associated State Machines - A Lightweight Formal Approach
No full textWe propose a precise definition of UML active classes through associated labelled transition systems using the algebraic Specification language Casl. We are convinced that the first step to make UML precise is to find an underlying formal model for the systems modelled by UML, and we argue that labelled transition systems are a sensible choice. This modelization will help understanding the UML constructs and will improve their use in practice. One of our aims is, in the future, to use the powerful animation and verification tools available for algebraic specifications with UML Specifications. We simplify the problem of the applicability of our semantics by restricting the state machine constructs considered. This restriction does not, however, narrow the UML subset in study because the restricted constructs can be replaced by equivalent combinations of other constructs. Because of some ambiguities in the UML official semantics, we discuss the several options at hand and choose, for each ambiguous case, the semantics that either makes more sense or that allows to simplify the problem the most
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
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