Safe Navigation in OCL

Abstract. The null object has been useful and troublesome ever since it was introduced. The problems have been mitigated by references in C++, annotations in Java or safe navigation in Groovy, Python and Xbase. Introduction of a safe navigation operator to OCL has some rather unpleasant consequences. We examine these consequences and identify further OCL refinements that are needed to make safe navigation useable

C# 3.0 makes OCL redundant!

Other than its 'platform independence' the major advantages of OCL over traditional Object Oriented programming languages has been the declarative nature of the language, its powerful navigation facility via the iteration operations, and the availability of tuples as a first class concept. The recent offering from Microsoft of the "Orcas" version of Visual Studio with C# 3.0 and the Linq library provides functionality almost identical to that of OCL. This paper examines and evaluates the controversial thesis that, as a result of C# 3.0, OCL is essentially redundant, having been superseded by the incorporation of its advantageous features into a mainstream programming language

Simplification of UML/OCL schemas for efficient reasoning

Ensuring the correctness of a conceptual schema is an essential task in order to avoid the propagation of errors during software development. The kind of reasoning required to perform such task is known to be exponential for UML class diagrams alone and even harder when considering OCL constraints. Motivated by this issue, we propose an innovative method aimed at removing constraints and other UML elements of the schema to obtain a simplified one that preserve the same reasoning outcomes. In this way, we can reason about the correctness of the initial artifact by reasoning on a simplified version of it. Thus, the efficiency of the reasoning process is significantly improved. In addition, since our method is independent from the reasoning engine used, any reasoning method may benefit from it.Peer ReviewedPostprint (author's final draft

Evaluation of Kermeta for Solving Graph-based Problems

Kermeta is a meta-language for specifying the structure and behavior of graphs of interconnected objects called models. In this paper,\ud we show that Kermeta is relatively suitable for solving three graph-based\ud problems. First, Kermeta allows the specification of generic model\ud transformations such as refactorings that we apply to different metamodels\ud including Ecore, Java, and Uml. Second, we demonstrate the extensibility\ud of Kermeta to the formal language Alloy using an inter-language model\ud transformation. Kermeta uses Alloy to generate recommendations for\ud completing partially specified models. Third, we show that the Kermeta\ud compiler achieves better execution time and memory performance compared\ud to similar graph-based approaches using a common case study. The\ud three solutions proposed for those graph-based problems and their\ud evaluation with Kermeta according to the criteria of genericity,\ud extensibility, and performance are the main contribution of the paper.\ud Another contribution is the comparison of these solutions with those\ud proposed by other graph-based tools

Panel discussion: Proposals for improving OCL

During the panel session at the OCL workshop, the OCL community discussed, stimulated by short presentations by OCL experts, potential future extensions and improvements of the OCL. As such, this panel discussion continued the discussion that started at the OCL meeting in Aachen in 2013 and on which we reported in the proceedings of the last year's OCL workshop. This collaborative paper, to which each OCL expert contributed one section, summarises the panel discussion as well as describes the suggestions for further improvements in more detail.Peer ReviewedPostprint (published version

Expressing Measurement Uncertainty in OCL/UML Datatypes

Uncertainty is an inherent property of any measure or estimation performed in any physical setting, and therefore it needs to be considered when modeling systems that manage real data. Although several modeling languages permit the representation of measurement uncertainty for describing certain system attributes, these aspects are not normally incorporated into their type systems. Thus, operating with uncertain values and propagating uncertainty are normally cumbersome processes, di cult to achieve at the model level. This paper proposes an extension of OCL and UML datatypes to incorporate data uncertainty coming from physical measurements or user estimations into the models, along with the set of operations de ned for the values of these types.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Framework for Agile Development of Component-Based Applications

Agile development processes and component-based software architectures are two software engineering approaches that contribute to enable the rapid building and evolution of applications. Nevertheless, few approaches have proposed a framework to combine agile and component-based development, allowing an application to be tested throughout the entire development cycle. To address this problematic, we have built CALICO, a model-based framework that allows applications to be safely developed in an iterative and incremental manner. The CALICO approach relies on the synchronization of a model view, which specifies the application properties, and a runtime view, which contains the application in its execution context. Tests on the application specifications that require values only known at runtime, are automatically integrated by CALICO into the running application, and the captured needed values are reified at execution time to resume the tests and inform the architect of potential problems. Any modification at the model level that does not introduce new errors is automatically propagated to the running system, allowing the safe evolution of the application. In this paper, we illustrate the CALICO development process with a concrete example and provide information on the current implementation of our framework

Surgical Management of Vesical Stones in Children: A Comparison Between Open cystolithotomy, Percutaneous Cystolithotomy and Transurethral Cystolithotripsy with Holmium-YAG Laser

Introduction: Bladder stone in children is rare but is more common in developing countries. In recent years, the urologists have trend to minimal invasive approaches. The aim of this study, was to compare the outcomes of surgical bladder stone management in our single tertiary center.Methods and materials: The 159 children younger than 18 years with vesical stones treated during January 2000 to January 2015 in Shohada e Tajrish hospital, Tehran, Iran that 146 subjects entered to the study. According to type of intervention, patients stratified to three groups. First group was included 80 patient’s that open cystolithotomy(OCL) was done for them, second group, 39 patients who underwent percutaneous cystolithotomy(PCCL)and third group,27 patients who treated by transurethral cystolithotripsy with holmium-YAG laser(TULL). Demographic data, operation time, hospital stay, and post operation complications were extracted and compared between groups.Results: Mean age was 8.3±5.1 years (8.6±5.1, 6±4.2 years for boys and girls, respectively). Mean stone size was 2.76±1.07 cm that was not significant between three groups but it was larger in OCL group. Mean operative time was 29.15(±7.12) min that in separate, mean operative time in TULL was significantly higher than PCCL and OCL respectively (36.3±5.97, 30.54±5.27 and 26.06±6.32 min/P:0.000). Mean hospital stay in OCL group was 3.55±1 day that was higher than PCCL and TULL groups significantly (P=0.000).Conclusion: based on our study, Ho:YAG lithotripsy is a safe with high success rate minimally invasive management method for children bladder calculi if proper equipment was available and done in expert hands