A Reverse Engineering Methodology for Extracting Parallelism From Design Abstractions.

Migration of code from sequential environments to the parallel processing environments is often done in an ad hoc manner. The purpose of this research is to develop a reverse engineering methodology to facilitate systematic migration of code from sequential to the parallel processing environments. The research results include the development of a three-phase methodology and the design and development of a reverse engineering toolkit (abbreviated as RETK) which serves to establish a working model for the methodology. The methodology consists of three phases: Analysis, Synthesis, and Transformation. The Analysis phase uses concepts from reverse engineering research to recover the sequential design description from programs using a new design recovery technique. The Synthesis phase is comprised of processes that compute the data and control dependences by using the design abstractions produced by the Analysis phase to construct the program dependence graph. The Transformation phase consists of processes that require knowledge-based analysis of the program and dependence information produced by the Analysis and Synthesis phases, respectively. Design recommendations for parallel environments are the key output of the Transformation phase. The main components of RETK are an Information Extractor, a Dependence Analyzer, and a Design Assistant that implement the processes of the Analysis, Synthesis, and Transformation phases, respectively. The object-oriented design and implementation of the Information Extractor and Dependence Analyzer are described. The design and implementation of the Design Assistant using C Language Interface Production System (CLIPS) are described. In addition, experimental results of applying the methodology to test programs by RETK are presented. The results include analysis of a Numerical Aerodynamic Simulation (NAS) benchmark program. By uniquely combining research in reverse engineering, dependence analysis, and knowledge-based analysis, the methodology provides a systematic approach for code migration. The benefits of using the methodology are increased comprehensibility and improved efficiency in migrating sequential systems to parallel environments

pBWT: Achieving succinct data structures for parameterized pattern matching and related problems

The fields of succinct data structures and compressed text indexing have seen quite a bit of progress over the last two decades. An important achievement, primarily using techniques based on the Burrows-Wheeler Transform (BWT), was obtaining the full functionality of the suffix tree in the optimal number of bits. A crucial property that allows the use of BWT for designing compressed indexes is order-preserving suffix links. Specifically, the relative order between two suffixes in the subtree of an internal node is same as that of the suffixes obtained by truncating the furst character of the two suffixes. Unfortunately, in many variants of the text-indexing problem, for e.g., parameterized pattern matching, 2D pattern matching, and order-isomorphic pattern matching, this property does not hold. Consequently, the compressed indexes based on BWT do not directly apply. Furthermore, a compressed index for any of these variants has been elusive throughout the advancement of the field of succinct data structures. We achieve a positive breakthrough on one such problem, namely the Parameterized Pattern Matching problem. Let T be a text that contains n characters from an alphabet , which is the union of two disjoint sets: containing static characters (s-characters) and containing parameterized characters (p-characters). A pattern P (also over ) matches an equal-length substring S of T i the s-characters match exactly, and there exists a one-to-one function that renames the p-characters in S to that in P. The task is to find the starting positions (occurrences) of all such substrings S. Previous index [Baker, STOC 1993], known as Parameterized Suffix Tree, requires (n log n) bits of space, and can find all occ occurrences in time O(jPj log +occ), where = jj. We introduce an n log +O(n)-bit index with O(jPj log +occlog n log ) query time. At the core, lies a new BWT-like transform, which we call the Parame- terized Burrows-Wheeler Transform (pBWT). The techniques are extended to obtain a succinct index for the Parameterized Dictionary Matching problem of Idury and Schaer [CPM, 1994]

ASSESSING THE QUALITY OF SOFTWARE DEVELOPMENT TUTORIALS AVAILABLE ON THE WEB

Both expert and novice software developers frequently access software development resources available on the Web in order to lookup or learn new APIs, tools and techniques. Software quality is affected negatively when developers fail to find high-quality information relevant to their problem. While there is a substantial amount of freely available resources that can be accessed online, some of the available resources contain information that suffers from error proneness, copyright infringement, security concerns, and incompatible versions. Use of such toxic information can have a strong negative effect on developer’s efficacy. This dissertation focuses specifically on software tutorials, aiming to automatically evaluate the quality of such documents available on the Web. In order to achieve this goal, we present two contributions: 1) scalable detection of duplicated code snippets; 2) automatic identification of valid version ranges. Software tutorials consist of a combination of source code snippets and natural language text. The code snippets in a tutorial can originate from different sources, perhaps carrying stringent licensing requirements or known security vulnerabilities. Developers, typically unaware of this, can reuse these code snippets in their project. First, in this thesis, we present our work on a Web-scale code clone search technique that is able to detect duplicate code snippets between large scale document and source code corpora in order to trace toxic code snippets. As software libraries and APIs evolve over time, existing software development tutorials can become outdated. It is difficult for software developers and especially novices to determine the expected version of the software implicit in a specific tutorial in order to decide whether the tutorial is applicable to their software development environment. To overcome this challenge, in this thesis we present a novel technique for automatic identification of the valid version range of software development tutorials on the Web

Extraçao de regras de integridade referencial a partir do código fonte

Orientador: Marcos Sfair SunyeDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Informática. Defesa: Curitiba, 2002Inclui bibliografiaResumo: Para atender a solicitações de manutenção em sistemas de informação, os responsáveis pelo sistema necessitam conhecer suas funcionalidades, regras de negócio, ou pelo menos, a parte do sistema que será afetada pela alteração. Esta pode ser uma tarefa simples quando executada por quem construiu o sistema, mas se torna complexa quando o projetista original foi deslocado para outras funções ou não está mais na empresa e não existe documentação para obter as informações necessárias. Neste caso, para ajudar a resolver o problema é necessário buscar informações em todos os lugares onde possam existir. Elas podem ser obtidas do esquema do banco de dados, com colegas que participaram na construção do sistema, com o usuário e nos códigos fonte dos programas, sendo este último um dos recursos mais utilizados. Quando se pretende obter informações gerenciais com cruzamento de variáveis, a falta do conhecimento das relações e regras de integridade, podem levar a resultados imprecisos ou equivocados e comprometer decisões importantes. Para fazer reengenharia de sistemas ou para criação de bases de informações gerencias o conhecimento de relações e regras de integridade são de igual forma fundamental. Por isso a proposta deste trabalho é mostrar que é possível identificar, extrair e armazenar regras de integridade referencial do código fonte para subsidiar estas atividades.Abstract: In order to attend the information system maintenance demands an information technology professional needs to know the system as well as its functionalities and business norms, or at least the system portion that will be affected by the alteration. This can be a simple task when performed by the one who developed the system, but it can become a complex one when the system original developer has been transferred to other activities or is no longer working for the company and there's not enough documentation to obtain the needed information. In this case, to help solving the problem, it's necessary to search for information everywhere it may be available. The information is often searched for in the data base schema, with other professionals who took place in the system developing process, with the system users and in the written programs, being this one of the most used ones. To extract relational semantics from source code program is not an easy nor a fast way of obtaining the needed information and this is a proposal for this task