Refactoring OCL annotated UML class diagrams

Refactoring of UML class diagrams is an emerging research topic and heavily inspired by refactoring of program code written in object-oriented implementation languages. Current class diagram refactoring techniques concentrate on the diagrammatic part but neglect OCL constraints that might become syntactically incorrect by changing the underlying class diagram. This paper formalizes the most important refactoring rules for class diagrams and classifies them with respect to their impact on attached OCL constraints. For refactoring rules that have an impact on OCL constraints, we formalize the necessary changes of the attached constraints. Our refactoring rules are specified in a graph-grammar inspired formalism. They have been implemented as QVT transformation rules. We finally discuss for our refactoring rules the problem of syntax preservation and show, by using the KeY-system, how this can be resolve

Uticaj elektronske komunikacije na virtuelne organizacije

U radu se istražuju načini uspostavljanja komunikacija u virtuelnim organizacijama. Autori zaključuju da uprkos novim tehnologijama kao važnom aspektu funkcionisanja virtuelnih organizacija, još uvek ljudski faktor ima presudan uticaj na obavljanje njihovih aktivnosti. Takođe, posebno je istaknuto da se s razvojem novih tehnologija, mogu i u budućnosti očekivati radikalne promene u načinima komunikacije u virtuelnim organizacijama. Medjutim, po mišljenju autora, nije lako unapred predvideti smer u kojem će te promene biti orijentisane. Ono što je sigurno predvidivo, jeste činjenica da će one zavisiti ne samo od tehnoloških promena, već i od promena u svesti zaposlenih u virtuelnim organizacijama

Semantics of OCL specified with QVT

The Object Constraint Language (OCL) has been for many years formalized both in its syntax and semantics in the language standard. While the official definition of OCL's syntax is already widely accepted and strictly supported by most OCL tools, there is no such agreement on OCL's semantics, yet. In this paper, we propose an approach based on metamodeling and model transformations for formalizing the semantics of OCL. Similarly to OCL's official semantics, our semantics formalizes the semantic domain of OCL, i.e. the possible values to which OCL expressions can evaluate, by a metamodel. Contrary to OCL's official semantics, the evaluation of OCL expressions is formalized in our approach by model transformations written in QVT. Thanks to the chosen format, our semantics definition for OCL can be automatically transformed into a tool, which evaluates OCL expressions in a given context. Our work on the formalization of OCL's semantics resulted also in the identification and better understanding of important semantic concepts, on which OCL relies. These insights are of great help when OCL has to be tailored as a constraint language of a given DSL. We show on an example, how the semantics of OCL has to be redefined in order to become a constraint language in a database domai

Composition of UML Described Refactoring Rules

Refactorings represent a powerful approach for improving the quality of software systems. A refactoring can be seen as a special kind of behavior preserving model transformation. The Object Constraint Language (OCL) together with the metamodel of Unified Modeling Language (UML) can be used for defining rules for refactoring UML models. This paper investigates descriptions of refactoring rules that can be checked, reused and composed. The main contribution of this paper is an algorithm to compute the description of sequentially composed transformations. This allows one to check if a sequence of transformations is successfully applicable for a given model before the transformations are executed on it. Furthermore, it facilitates the analysis of the effects of transformation chain and its usage in other compositions

A Graphical Approach to Prove the Semantic Preservation of UML/OCL Refactoring Rules

Refactoring is a powerful technique to improve the quality of software models including implementation code. The software developer applies successively so-called refactoring rules on the current software model and transforms it into a new model. Ideally, the application of a refactoring rule preserves the semantics of the model on which it is applied. In this paper, we present a simple criterion and a proof technique for the semantic preservation of refactoring rules that are defined for UML class diagrams and OCL constraints. Our approach is based on a novel formalization of the OCL semantics in form of graph transformation rules. We illustrate our approach using the refactoring rule MoveAttribute

Refactoring OCL Annotated UML Class Diagrams

Refactoring of UML class diagrams is an emerging research topic and heavily inspired by refactoring of program code written in object-oriented implementation languages. Current class diagram refactoring techniques concentrate on the diagrammatic part but neglect OCL constraints that might become syntactically incorrect by changing the underlying class diagram. This paper formalizes the most important refactoring rules for class diagrams and classifies them with respect to their impact on annotated OCL constraints. For refactoring rules, whose application on class diagrams could make attached OCL constraints incorrect, we formally describe how the OCL constraints have to be refactored to preserve their syntactical correctness. Our refactoring rules are defined in the graph-grammar based formalism proposed by the QVT Merge Group for the specification of model transformations

RoclET – A Tool for Wrestling with OCL Specifications

In this paper, we describe the architecture and the functionality of our own OCL tool called RoclET. Besides standard features of OCL tools such as editing of class and object diagrams and parsing of OCL assertions (invariants, pre-/post-conditions), our tool supports also the evaluation of OCL constraints in a given system snapshot (object diagram), refactoring of UML/OCL models, and impact analysis. RoclET is deployed in form of an Eclipse plugin

MONITORING OF POTATO FIELDS TO PRESENCE OF RALSTONIA SOLANACEARUM

BACKGROUNDS: Ralstonia solanacearum race 3 biovar 2 is one of the most important plant pathogenic bacteria because of its persistence, wide host range and widespread. It´s causing bacterial wilt of over 250 plant species, including many cultivated crops (potato, tomato, eggplant, geranium, ginger, banana, etc.) and brown rot of potato. OBJECTIVES: The aim of this study was to determine presence of R. solanacearum based on several years monitoring of potato tubers. METHODS: During four-year period (2013-2016), 98 samples of potato tubers (11 cultivars), from 13 localities in Bačka and 1 in Podunavlje region were examined. Isolation from potato tubers with brown rot symptom was performed on semi-selective SMSA medium. PCR method using Ps-1/Ps-2 and OLY1/Y2 primers and immunofluorescence were used to detect presence of R. solanacearum. Pathogenicity was tested on young tomato plants. RESULTS: In 2013, R. solanacearum was detected in 1 sample of potato tuber (Lady Claire) from Srpski Miletić; in 2015 in 2 (Crisps4all, VR 808) from Srpski Miletić and 1 (VR 808) from Stapar; during 2016 in 2 (Crisps4all, Brooke) from Srpski Miletić, 2 (Lady Claire, VR 808) from Stapar, 2 (Lady Claire, Pirol) from Sombor and 1 (Panda) from Boleč. Milky-white, with pink to red centre, flat, irregular, fluidal colonies formed after 3-4 days of incubation on SMSA medium. A 553 bp and 288 bp fragments of 65 representative isolates were amplified using Ps-1/Ps-2 and OLY1/Y2 primer pairs, respectively. IF test proved presence of fluorescent bacterial cells. All strains caused wilting on tomato seedlings four days after inoculation. CONCLUSIONS: The results of this study detected presence of R. solanacearum on 11 potato samples isolated from four locations during period from 2013-2016

Genetic diversity of pseudomonas syringae pv. Syringae isolated from sweet cherry in southern and northern regions in Serbia

Bacterial canker and leaf spot caused by plant pathogenic bacterium Pseudomonas is among the most destructive cherry diseases worldwide. Nowadays in Serbia, sweet cherry production significantly increased and the new plantations, mainly grown from imported planting material are being raised every year. During spring, 2018 and 2019, occurrence of bacterial canker and leaf spot symptoms was observed on a newly planted sweet cherry plantations in two localities, Zitorada (Southern region) and Karavukovo (Northern region-Vojvodina). Typical P. syringae colonies were isolated on Nutrient Sucrose Agar supplemented with 5% sucrose (NSA). A total of fifteen isolates were selected and identified. Results of the LOPAT test (+---+) determined them to belong to fluorescent Pseudomonas Group Ia, while results of G(+)A(+)T(-)Ta(-) tests indicate presence of Pseudomonas syringae pv. syringae. Pathogenicity was confirmed on immature sweet and sour cherry fruitlets by forming of black, sunken lesions for all tested isolates. Genes syrB and syrD were successfully detected in all tested isolates. DNA sequencing using gapA, gltA, gyrB and rpoD housekeeping genes determined tested isolates to belong to P. s. pv. syringae using the National Center for Biotechnology Information (NCBI) nucleotide BLAST. The Serbian isolates shared 99.47% to 100% (Zitorada) and 99.38% to 100% (Karavukovo) identity with bacterium P. s. pv. syringae. Phylogenetic analysis grouped isolates from Zitorada in one tree cluster, separate from the Karavukovo isolates,indicating presence of two genetically diverse groups of causal pathogen P. s. pv. syringae, obtained from two geographically distinct localities in Serbia. Phylogeographic analysis grouped isolates from Zitorada in multilocus haplotype coded as REz and isolates originated from Karavukovo in multilocus haplotype coded as REk. Considering that during last few years P. syringae continuously occurs mainly in young sweet cherry plantations, where imported material is used for raising, health status check is recommended to be included as obligatory measure when nursery material is used from import

MULTILOCUS SEQUENCE ANALYSIS OF RALSTONIA SOLANACEARUM ISOLATES ORIGINATED FROM POTATO IN SERBIA

Ralstonia solanacearum is a soil borne bacterium which affects more than 450 plant species including a wide range of crop plants, ornamentals and weeds. This bacterium is causing bacterial wilt disease which leads to severe economic losses. On potato, disease is known as brown rot. Even though this phytopathogen originates from tropic, subtropics and warm temperate regions, in recent years cold-adapted strains dramatically enhanced the threat of European potato crops, including Serbia. R. solanacearum is at A2 list of quarantine plant pathogens in Europe. During six year period (2013-2018), isolates from diseased potato tubers were collected, identified using Multilocus sequence analysis (MLSA) and checked for certain phylotype affiliation. DNA from the obtained isolates was amplified using seven housekeeping genes (adk, fliC, gapA, gdhA, gyrB, hrpB, ppsA) and sequenced. Phylogenetic analysis was performed with concatenated sequences of all tested isolates, and compared with the most similar R. solanacearum strains from PAMDB database. All Serbian isolates were identified as R. solanacearum using PAMDB BLAST. Neighbor-joining phylogenetic analysis placed tested isolates in the same cluster with R. solanacearum strains belonging to race 3, biovar 2, and phylotype II obtained from PAMDB. Although, bacterial wilt caused by this plant pathogenic bacteria is appearing in different locations and on different potato cultivars in Serbia it remained genetically homogenous. Currently, R. solanacearum is a quarantine bacteria occurring only on potato in our country, but considering its wide host range, there is a possibility of it causing disease on other significant crops with devastating consequences. Therefore, its fast and accurate identification and mapping is of main interest for stopping the disease spread