A Generic Technique for Domain-Specific Visual Language Model Refactoring to Patterns

As the popularity of domain-specific visual languages (DSVLs) grows, concerns have arisen regarding quality assurance and evolvability of their meta-models and model instances. In this paper we address aspects of automated DSVL model instance modification for quality improvement based on refactoring specifications. We propose a graph transformation-based visual language approach for DSVL authors to specify the matching and discovery of DSVL “bad model smells” and the application of pattern-based solutions in a DSVL meta-tool. As an outcome, DSVL users are provided with pattern-based design evolution support as refactorings for their DSVL-based domain models

Handling High-Level Model Changes Using Search Based Software Engineering

Model-Driven Engineering (MDE) considers models as first-class artifacts during the software lifecycle. The number of available tools, techniques, and approaches for MDE is increasing as its use gains traction in driving quality, and controlling cost in evolution of large software systems. Software models, defined as code abstractions, are iteratively refined, restructured, and evolved. This is due to many reasons such as fixing defects in design, reflecting changes in requirements, and modifying a design to enhance existing features. In this work, we focus on four main problems related to the evolution of software models: 1) the detection of applied model changes, 2) merging parallel evolved models, 3) detection of design defects in merged model, and 4) the recommendation of new changes to fix defects in software models. Regarding the first contribution, a-posteriori multi-objective change detection approach has been proposed for evolved models. The changes are expressed in terms of atomic and composite refactoring operations. The majority of existing approaches detects atomic changes but do not adequately address composite changes which mask atomic operations in intermediate models. For the second contribution, several approaches exist to construct a merged model by incorporating all non-conflicting operations of evolved models. Conflicts arise when the application of one operation disables the applicability of another one. The essence of the problem is to identify and prioritize conflicting operations based on importance and context – a gap in existing approaches. This work proposes a multi-objective formulation of model merging that aims to maximize the number of successfully applied merged operations. For the third and fourth contributions, the majority of existing works focuses on refactoring at source code level, and does not exploit the benefits of software design optimization at model level. However, refactoring at model level is inherently more challenging due to difficulty in assessing the potential impact on structural and behavioral features of the software system. This requires analysis of class and activity diagrams to appraise the overall system quality, feasibility, and inter-diagram consistency. This work focuses on designing, implementing, and evaluating a multi-objective refactoring framework for detection and fixing of design defects in software models.Ph.D.Information Systems Engineering, College of Engineering and Computer ScienceUniversity of Michigan-Dearbornhttp://deepblue.lib.umich.edu/bitstream/2027.42/136077/1/Usman Mansoor Final.pdfDescription of Usman Mansoor Final.pdf : Dissertatio

Search-Based Information Systems Migration: Case Studies on Refactoring Model Transformations

Information systems are built to last for decades; however, the reality suggests otherwise. Companies are often pushed to modernize their systems to reduce costs, meet new policies, improve the security, or to be more competitive. Model-driven engineering (MDE) approaches are used in several successful projects to migrate systems. MDE raises the level of abstraction for complex systems by relying on models as first-class entities. These models are maintained and transformed using model transformations (MT), which are expressed by means of transformation rules to transform models from source to target meta-models. The migration process for information systems may take years for large systems. Thus, many changes are going to be introduced to the transformations to reflect the new business requirements, fix bugs, or to meet the updated metamodels. Therefore, the quality of MT should be continually checked and improved during the evolution process to avoid future technical debts. Most MT programs are written as one large module due to the lack of refactoring/modularization and regression testing tools support. In object-oriented systems, composition and modularization are used to tackle the issues of maintainability and testability. Moreover, refactoring is used to improve the non-functional attributes of the software, making it easier and faster for developers to work and manipulate the code. Thus, we proposed an intelligent computational search approach to automatically modularize MT. Furthermore, we took inspiration from a well-defined quality assessment model for object-oriented design to propose a quality assessment model for MT in particular. The results showed a 45% improvement in the developer’s speed to detect or fix bugs, and developers made 40% less errors when performing a task with the optimized version. Since refactoring operations changes the transformation, it is important to apply regression testing to check their correctness and robustness. Thus, we proposed a multi-objective test case selection technique to find the best trade-off between coverage and computational cost. Results showed a drastic speed-up of the testing process while still showing a good testing performance. The survey with practitioners highlighted the need of such maintenance and evolution framework to improve the quality and efficiency of the existing migration process.Ph.D.College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttp://deepblue.lib.umich.edu/bitstream/2027.42/149153/1/Bader Alkhazi Final Dissertation.pdfDescription of Bader Alkhazi Final Dissertation.pdf : Restricted to UM users only