Improving the OCL Semantics Definition by Applying Dynamic Meta Modeling and Design Patterns

OCL is a standard specification language, which will probably be supported by most software modeling tools in the near future. Hence, it is important for OCL to have a solid formal foundation, for its syntax and its semantic definition. Currently, OCL is being formalized by metamodels expressed in MOF, complemented by well formedness rules written in the own OCL. This recursive definition not only brings about formal problems, but also puts obstacles in language understanding. On the other hand, the OCL semantics metamodel presents quality weaknesses due to the fact that certain object-oriented design rules (patterns) were not obeyed in their construction. The aim of the proposal presented in this article is to improve the definition for the OCL semantics metamodel by applying GoF patterns and the dynamic metamodeling technique. Such proposal avoids circularity in OCL definition and increases its extensibility, legibility and accuracy

On the semantics of redefinition, specialization and subsetting of associations in UML (extended version)

The definition of the exact meaning of conceptual modeling concepts is considered a relevant issue since it enhances their effective and appropriate use by designers and facilitates the automatic processing of the models where they are included. Three related concepts that permit to improve the definition of an association in UML and which still lack of a formal semantic definition are: association redefinition, association specialization and association subsetting. This paper formalizes their semantics and points out the similarities and differences that exist among them. The formalization we propose is based on the meta-modelling approach and a semantic domain composed of a set of basic UML concepts and OCL expressions, which have a previous formal definition in the literature and which are well-understood.Preprin

Ontologies and Unified Modeling Language: an approach to representation of domains of knowledge

This article emphasizes the use of Unified Modeling Language, UML in the specification of models based on ontologies in the representation of domains of knowledge, emphasizing the importance of semantic and of treatment of standardized language so the knowledge of the domain can be organized and shared. Finally, this article aims to establish a connection between the themes: the object oriented modeling and ontologies.Este artigo destaca o uso da Unified Modeling Language, UML na especificação de modelos baseados em ontologias na representação de domínios de conhecimento, enfatizando a importância da semântica e do tratamento da linguagem padronizada para que o conhecimento do domínio possa ser organizado e compartilhado. Finalmente, este artigo tem como objetivo estabelecer uma conexão entre as temáticas: modelagem orientada a objetos e ontologias

Finite satisfiability verification in UML class diagrams: a comparative study

Unified Modeling Language class diagrams are widely used for modeling, playing a key role in the analysis and design of information systems, especially in development contexts that use modeling oriented methodologies. Therefore, it is relevant to ensure the creation and maintenance of correct class diagrams. With the use of class diagrams it is possible to specify classes, relations and restrictions, however, such diagrams are subject to modeling errors made by their authors and may degenerate into incorrect diagrams. A common cause of incorrect diagrams refers to the definition of contradictory and inconsistent constraints, leading to finite satisfiability problems. Several approaches to the verification of finite satisfiability are currently available, supported by different tools. Through this work, we proceed with the identification and comparison of the existing approaches for the verification of finite satisfiability in class diagrams, determining the effectiveness and efficiency of the proposed tools

Developing and operating time critical applications in clouds: the state of the art and the SWITCH approach

Cloud environments can provide virtualized, elastic, controllable and high quality on-demand services for supporting complex distributed applications. However, the engineering methods and software tools used for developing, deploying and executing classical time critical applications do not, as yet, account for the programmability and controllability provided by clouds, and so time critical applications cannot yet benefit from the full potential of cloud technology. This paper reviews the state of the art of technologies involved in developing time critical cloud applications, and presents the approach of a recently funded EU H2020 project: the Software Workbench for Interactive, Time Critical and Highly self-adaptive cloud applications (SWITCH). SWITCH aims to improve the existing development and execution model of time critical applications by introducing a novel conceptual model—the application-infrastructure co-programming and control model—in which application QoS and QoE, together with the programmability and controllability of cloud environments, is included in the complete application lifecycle

Expressing Systemic Contexts in Visual Models of System Specifications

Decision support systems can be used to manage systems. Managed systems are described by system specifications. System specification notations, such as UML, often separate in different diagrams the static specification and the dynamic specification of the system of interest. As a consequence, precious contextual information disappears, leading to misunderstandings during the interpretation of the specification. We claim that these problems result from a mechanistic view of reality. By taking a systemic view of reality, it is possible to develop a specification technique that integrates the static and dynamic aspects of the system and, hence, make the contextual information explicit. The benefit is the creation of more expressive system specifications that are less error prone when used for designing and managing systems

On verifying ATL transformations using 'off-the-shelf' SMT solvers

International audienceMDE is a software development process where models constitute pivotal elements of the software to be built. If models are well-specified, transformations can be employed for various purposes, e.g., to produce final code. However, transformations are only meaningful when they are 'correct': they must produce valid models from valid input models. A valid model has conformance to its meta-model and fulfils its constraints, usually written in OCL. In this paper, we propose a novel methodology to perform automatic, unbounded verification of ATL transformations. Its main component is a novel first-order semantics for ATL transformations, based on the interpretation of the corresponding rules and their execution semantics as first-order predicates. Although, our semantics is not complete, it does cover a significant subset of the ATL language. Using this semantics, transformation correctness can be automatically verified with respect to non-trivial OCL pre- and postconditions by using SMT solvers, e.g. Z3 and Yices

An Experimental Scrutiny of Visual Design Modelling: VCL up against UML+OCL

The graphical nature of prominent modelling notations, such as the standards UML and SysML, enables them to tap into the cognitive benefits of diagrams. However, these notations hardly exploit the cognitive potential of diagrams and are only partially graphical with invariants and operations being expressed textually. The Visual Contract Language (VCL) aims at improving visual modelling; it tries to (a) maximise diagrammatic cognitive effectiveness, (b) increase visual expressivity, and (c) level of rigour and formality. It is an alternative to UML that does largely pictorially what is traditionally done textually. The paper presents the results of a controlled experiment carried out four times in different academic settings and involving 43 participants, which compares VCL against UML and OCL and whose goal is to provide insight on benefits and limitations of visual modelling. The paper's hypotheses are evaluated using a crossover design with the following tasks: (i) modelling of state space, invariants and operations, (ii) comprehension of modelled problem, (iii) detection of model defects and (iv) comprehension of a given model. Although visual approaches have been used and advocated for decades, this is the first empirical investigation looking into the effects of graphical expression of invariants and operations on modelling and model usage tasks. Results suggest VCL benefits in defect detection, model comprehension, and modelling of operations, providing some empirical evidence on the benefits of graphical software design

Redefinición de asociaciones en UML: semántica y utilización

Un inconveniente importante que presenta hoy en día UML es la falta de semántica formal. Existen muchos conceptos que no define con la suficiente precisión como para que puedan ser interpretados sin ambigüedades. Uno de los principales objetivos de este trabajo es precisar la semántica de la redefinición de asociaciones, un constructor de UML que nos permite definir de manera más específica extremos de asociaciones. Así mismo, comparamos este constructor con conceptos similares, como el subsetting (de UML) o el refinamiento de asociaciones (de otros lenguajes de modelado), con el objetivo de mostrar claramente que se tratan de conceptos semánticamente diferentes. Todo ello ayudará al diseñador a hacer un uso correcto del constructor de la redefinición de asociaciones. Otra contribución significativa de este trabajo es la de incorporar a UML la semántica del refinamiento de asociaciones. Para ello, creamos nuevos estereotipos que nos permitirán incorporar todos aquellos casos que podemos expresar con el refinamiento y que no quedan cubiertos por la redefinición de asociaciones. Finalmente, implementamos estos estereotipos en la herramienta CASE PoseidonUML