Regras de refatoração para banco de dados baseado em grafos

Orientador: Luiz Camolesi JúniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de TecnologiaResumo: A informação produzida atualmente apresenta crescimento em volume e complexidade, representando um desafio tecnológico que demanda mais do que a atual estrutura de Bancos de Dados Relacionais pode oferecer. Tal fato estimula o uso de diferentes formas de armazenamento, como Bancos de Dados baseados em Grafos (BDG). Os atuais Bancos de Dados baseados em Grafos são adaptados para suportar automaticamente a evolução do banco de dados, mas não fornecem recursos adequados para a organização da informação. Esta função é deixada a cargo das aplicações que acessam o banco de dados, comprometendo a integridade dos dados e sua confiabilidade. O objetivo deste trabalho é a definição de regras de refatoração para auxiliar o gerenciamento da evolução de Bancos de Dados baseados em Grafos. As regras apresentadas neste trabalho são adaptações e extensões de regras de refatoração consolidadas para bancos de dados relacionais para atender às características dos Bancos de Dados baseado em Grafos. O resultado deste trabalho é um catálogo de regras que poderá ser utilizado por desenvolvedores de ferramentas de administração de bancos de dados baseados em grafos para garantir a integridade das operações de evolução de esquemas de dados e consequentemente dos dados relacionadosAbstract: The information produced nowadays does not stop growing in volume and complexity, representing a technological challenge which demands more than the relational model for databases can currently offer. This situation stimulates the use of different forms of storage, such as Graph Databases. Current Graph Databases allow automatic database evolution, but do not provide adequate resources for the information organization. This is mostly left under the responsibility of the applications which access the database, compromising the data integrity and reliability. The goal of this work is the definition of refactoring rules to support the management of the evolution of Graph Databases. The rules presented in this document are adaptations and extensions of the existent refactoring rules for relational databases to meet the requirements of the Graph Databases features. The result of this work is a catalog of refactoring rules that can be used by developers of graph database management tools to guarantee the integrity of the operations of database evolutionMestradoTecnologia e InovaçãoMestra em Tecnologi

A heuristic-based approach to code-smell detection

Encapsulation and data hiding are central tenets of the object oriented paradigm. Deciding what data and behaviour to form into a class and where to draw the line between its public and private details can make the difference between a class that is an understandable, flexible and reusable abstraction and one which is not. This decision is a difficult one and may easily result in poor encapsulation which can then have serious implications for a number of system qualities. It is often hard to identify such encapsulation problems within large software systems until they cause a maintenance problem (which is usually too late) and attempting to perform such analysis manually can also be tedious and error prone. Two of the common encapsulation problems that can arise as a consequence of this decomposition process are data classes and god classes. Typically, these two problems occur together – data classes are lacking in functionality that has typically been sucked into an over-complicated and domineering god class. This paper describes the architecture of a tool which automatically detects data and god classes that has been developed as a plug-in for the Eclipse IDE. The technique has been evaluated in a controlled study on two large open source systems which compare the tool results to similar work by Marinescu, who employs a metrics-based approach to detecting such features. The study provides some valuable insights into the strengths and weaknesses of the two approache

Automated Refactoring in Software Automation Platforms

Software Automation Platforms (SAPs) enable faster development and reduce the need to use code to construct applications. SAPs provide abstraction and automation, result- ing in a low-entry barrier for users with less programming skills to become proficient developers. An unfortunate consequence of using SAPs is the production of code with a higher technical debt since such developers are less familiar with the software develop- ment best practices. Hence, SAPs should aim to produce a simpler software construction and evolution pipeline beyond providing a rapid software development environment. One simple example of such high technical debt is the Unlimited Records anti-pattern, which occurs whenever queries are unbounded, i.e. the maximum number of records to be fetched is not explicitly limited. Limiting the number of records retrieved may, in many cases, improve the performance of applications by reducing screen-loading time, thus making applications faster and more responsive, which is a top priority for developers. A second example is the Duplicated Code anti-pattern that severely affects code readability and maintainability, and can even be the cause of bug propagation. To overcome this problem we will resort to automated refactoring as it accelerates the refactoring process and provides provably correct modifications. This dissertation aims to study and develop a solution for automated refactorings in the context of OutSystems (an industry-leading SAP). This was carried out by implement- ing automated techniques for automatically refactoring a set of selected anti-patterns in OutSystems logic that are currently detected by the OutSystems technical debt monitor- ing tool.As Plataformas de Automação de Software (PAS) habilitam os seus utilizadores a desen- volver aplicações de forma mais rápida e reduzem a necessidade de escrever código. Estas fornecem abstração e automação, o que auxilia utilizadores com menos formação técnica a tornarem-se programadores proficientes. No entanto, a integração de programadores com menos formação técnica também contribui para a produção de código com alta dívida técnica, uma vez que os mesmos estão menos familiarizados com as melhores práticas de desenvolvimento de software. Desta forma, as PAS devem ter como objetivo a cons- trução e evolução de software de forma simples para além de fornecer um ambiente de desenvolvimento de software rápido. Um exemplo de alta dívida técnica é o anti-padrão Unlimited Records, que ocorre sempre que o número máximo de registos a ser retornado por uma consulta à base de dados não é explicitamente limitado. Limitar o número de registos devolvidos pode, em muitos casos, melhorar o desempenho das aplicações, reduzindo o tempo que demora a carregar o ecrã, tornando assim as aplicações mais rápidas e responsivas, sendo esta uma das principais prioridades dos programadores. Um segundo exemplo é o anti-padrão Código Duplicado que afeta gravemente a legibilidade e manutenção do código, e que pode causar a propagação de erros. Para superar este problema, recorreremos à reestru- turação automatizada, pois acelera o processo de reestruturação através de modificações comprovadamente corretas. O objetivo desta dissertação é estudar e desenvolver uma solução para reestruturação automatizada no contexto da OutSystems (uma PAS líder neste setor). Tal foi realizado através da implementação de técnicas automatizadas para reestruturar um conjunto de anti-padrões que são atualmente detetados pela ferramenta de monitorização de dívida técnica da OutSystems

Integrated data model and DSL modifications

Companies are increasingly more and more dependent on distributed web-based software systems to support their businesses. This increases the need to maintain and extend software systems with up-to-date new features. Thus, the development process to introduce new features usually needs to be swift and agile, and the supporting software evolution process needs to be safe, fast, and efficient. However, this is usually a difficult and challenging task for a developer due to the lack of support offered by programming environments, frameworks, and database management systems. Changes needed at the code level, database model, and the actual data contained in the database must be planned and developed together and executed in a synchronized way. Even under a careful development discipline, the impact of changing an application data model is hard to predict. The lifetime of an application comprises changes and updates designed and tested using data, which is usually far from the real, production, data. So, coding DDL and DML SQL scripts to update database schema and data, is the usual (and hard) approach taken by developers. Such manual approach is error prone and disconnected from the real data in production, because developers may not know the exact impact of their changes. This work aims to improve the maintenance process in the context of Agile Platform by Outsystems. Our goal is to design and implement new data-model evolution features that ensure a safe support for change and a sound migration process. Our solution includes impact analysis mechanisms targeting the data model and the data itself. This provides, to developers, a safe, simple, and guided evolution process

Proceedings of the 2008 Oxford University Computing Laboratory student conference.

This conference serves two purposes. First, the event is a useful pedagogical exercise for all participants, from the conference committee and referees, to the presenters and the audience. For some presenters, the conference may be the first time their work has been subjected to peer-review. For others, the conference is a testing ground for announcing work, which will be later presented at international conferences, workshops, and symposia. This leads to the conference's second purpose: an opportunity to expose the latest-and-greatest research findings within the laboratory. The fourteen abstracts within these proceedings were selected by the programme and conference committee after a round of peer-reviewing, by both students and staff within this department