Increasing the number of processors has become the mainstream for the modern chip design approaches. However, most applications are designed or written for single core processors; so they do not benefit from the numerous underlying computation resources. Moreover, there exists a large base of legacy software which requires an immense effort and cost of rewriting and re-engineering to be made parallel. In the past decades, there has been a growing interest in automatic parallelization. This is to relieve programmers from the painful and error-prone manual parallelization process, and to cope with new architecture trend of multi-core and many-core CPUs. Automatic parallelization techniques vary in properties such as: the level of paraellism (e.g., instructions, loops, traces, tasks); the need for custom hardware support; using optimistic execution or relying on conservative decisions; online, offline or both; and the level of source code exposure. Transactional Memory (TM) has emerged as a powerful concurrency control abstraction. TM simplifies parallel programming to the level of coarse-grained locking while achieving fine-grained locking performance. This dissertation exploits TM as an optimistic execution approach for transforming a sequential application into parallel. The design and the implementation of two frameworks that support automatic parallelization: Lerna and HydraVM, are proposed, along with a number of algorithmic optimizations to make the parallelization effective. HydraVM is a virtual machine that automatically extracts parallelism from legacy sequential code (at the bytecode level) through a set of techniques including code profiling, data dependency analysis, and execution analysis. HydraVM is built by extending the Jikes RVM and modifying its baseline compiler. Correctness of the program is preserved through exploiting Software Transactional Memory (STM) to manage concurrent and out-of-order memory accesses. Our experiments show that HydraVM achieves speedup between 2×-5× on a set of benchmark applications. Lerna is a compiler framework that automatically and transparently detects and extracts parallelism from sequential code through a set of techniques including code profiling, instrumentation, and adaptive execution. Lerna is cross-platform and independent of the programming language. The parallel execution exploits memory transactions to manage concurrent and out-of-order memory accesses. This scheme makes Lerna very effective for sequential applications with data sharing. This thesis introduces the general conditions for embedding any transactional memory algorithm into Lerna. In addition, the ordered version of four state-of-art algorithms have been integrated and evaluated using multiple benchmarks including RSTM micro benchmarks, STAMP and PARSEC. Lerna showed great results with average 2.7× (and up to 18×) speedup over the original (sequential) code. While prior research shows that transactions must commit in order to preserve program semantics, placing the ordering enforces scalability constraints at large number of cores. In this dissertation, we eliminates the need for commit transactions sequentially without affecting program consistency. This is achieved by building a cooperation mechanism in which transactions can forward some changes safely. This approach eliminates some of the false conflicts and increases the concurrency level of the parallel application. This thesis proposes a set of commit order algorithms that follow the aforementioned approach. Interestingly, using the proposed commit-order algorithms the peak gain over the sequential non-instrumented execution in RSTM micro benchmarks is 10× and 16.5× in STAMP. Another main contribution is to enhance the concurrency and the performance of TM in general, and its usage for parallelization in particular, by extending TM primitives. The extended TM primitives extracts the embedded low level application semantics without affecting TM abstraction. Furthermore, as the proposed extensions capture common code patterns, it is possible to be handled automatically through the compilation process. In this work, that was done through modifying the GCC compiler to support our TM extensions. Results showed speedups of up to 4× on different applications including micro benchmarks and STAMP. Our final contribution is supporting the commit-order through Hardware Transactional Memory (HTM). HTM contention manager cannot be modified because it is implemented inside the hardware. Given such constraint, we exploit HTM to reduce the transactional execution overhead by proposing two novel commit order algorithms, and a hybrid reduced hardware algorithm. The use of HTM improves the performance by up to 20% speedup. / Ph. D.

With the widespread use of the Internet and its associated technologies, enterprises have to evolve in the way they are conducting business. 'e-business applications' refer to a new class of distributed applications that involves the Internet as a communication platform. Each e-business application supports the full automation of business processes that can span across multiple enterprises. For a given application domain that involves e-business application development, a number of design decisions that best fullfil stakeholders requirements have to be made. One important issue is the reuse of functionality which exists within legacy systems that can belong to one or more enterprises within the same domain. Most existing design approaches are inadequate in supporting the exploration of all design combinations. Moreover, there is little work on how to identify the best design decisions systematically for a given application domain. In this thesis we present a pattern-based approach that addresses the architectural design of e-business applications. We identify a number of architectural patterns whose instantiation on a given design problem correspond to different architectural design alternatives. We also identify models that enable the estimation of quality attributes for such alternatives. Then we investigate and utilise methods to select the best pattern for a given design problem. We also describe the process of generating the alternative architectures, estimating their qualities, and then ranking them with respect to any quality attribute or a combination of quality attributes. We validate this approach on a real life case study in the area of capital markets. The case study concerns realistic e-business applications that rely on existing legacy applications. The validation exercise has produced predictions which have been compared with actual design decisions that have been made. The thesis also proposes a framework for the systematic identification of architectural patterns. An additional set of architectural patterns and their impact on the case study are discussed. The main contribution of this thesis is in the identification of patterns and quality attributes models for the architectural design of e-business applications that aid in the systematic selection of the most appropriate architectural pattern for a given problem context.

This master thesis covers re-engineering methods of legacy systems. Legacy system is an old system, which is hardly compliant with modern technologies and used only because it has become an integral part of organization business process support during the long period of its maintenance. These systems are large, monolithic and difficult to modify, and cost and risk of their replacement are difficult to predict. The science of software engineering offers an incremental modernization of information systems applying the re-engineering of legacy software. The main goal of software re-engineering is to transform the software in the way, it would become easier to understand, maintain and re-use, at the same time preserving its useful, time trusted functions. The main re-engineering methods are source code translation, reverse engineering and data re-engineering. This thesis covers the analysis of these methods, which was made during the re-engineering of wood production and sales accounting system. The adoption and realization time rate of every method was examined. The influence of the applied re-engineering methods to the system reliability, efficiency, usability and other quality metrics is given.

Made available in DSpace on 2016-06-02T19:05:18Z (GMT). No. of bitstreams: 1 DissFJA.pdf: 3257954 bytes, checksum: 6cf58fbd124ba9dd6b97f1f8ea5b6b2a (MD5) Previous issue date: 2003-09-05 / With the technological evolution and the increasing utilization of the Internet, companies and governmental institutions have been looking for modern solution to replace and improve their legacy systems. These kind of solutions require high investments, being able to use the reengineering process in these cases. A maner to modify these systems is through reengineering of their interfaces, by wrapping of their logic. This technique preserves the native environment of system and its functionalities, reducing in time and cost the reengineering process. To support the migration of legacies systems in a general way, there is an Interface Reengineering Process (IRP), whose accomplish the wrapping of its functionalities and connect them with a new user Web interface. This Web interface connects itself with the identified components of the legacy system following the special resources that they offer. The IRP is summarized by the study of the interface and logic of the system. In this way, it possible to accomplish the system organization for the wrapping to be done, which is composed by the legacies functionalities covered by a new software layer. This new layer makes possible the communication with the new user interface, which has developed according to the usability criteria. The systems used as case studies were developed using Delphi environment, with or without object orientation characteristics. In this work only systems developed without object orientation characteristics are presented in details. With the use of the new process proposed here, the interface can be developed in any paradigm, while the legacy code remains as the original, simplyfing the system maintenance. / Com a evolução tecnológica e com a crescente utilização da Internet, empresas e instituições governamentais desejam migrar seus sistemas desenvolvidos com recursos computacionais antigos (legados) para mais modernos. No entanto, essa é uma tarefa que requer investimentos elevados, podendo o processo de reengenharia ser utilizado nesses casos. Uma forma de modificar esses sistemas é por meio da reengenharia da sua interface, através do empacotamento de sua lógica (wrapping). Essa técnica preserva o ambiente nativo do sistema e suas funcionalidades, reduzindo em tempo e custo o processo de reengenharia. Para apoiar a migração de sistemas legados propõe-se um Processo de Reengenharia de Interface (PRI) que apóia a migração de sistemas legados de maneira geral, realizando o empacotamento de suas funcionalidades e acoplando uma nova interface do usuário para Web. A nova interface do usuário será disponibilizada para Web, que se comunica com os componentes identificados no sistema legado de acordo com os recursos especiais que eles oferecem. O PRI resume-se no estudo da interface e da lógica do sistema. Com isso, pode-se realizar a organização do sistema para que seja realizado seu empacotamento, que corresponde ao revestimento das funcionalidades legadas por uma camada de software, viabilizando a comunicação com a nova interface do usuário, desenvolvida segundo critérios de usabilidade. Os sistemas utilizados como estudo de casos são desenvolvidos no ambiente Delphi com ou sem características da orientação a objetos. Neste trabalho somente os desenvolvidos sem características da orientação a objetos são apresentados em detalhes. Com a aplicação desse processo, somente a interface passa a ser desenvolvida em um outro paradigma, mas o código legado permanece como o original, facilitando a tarefa dos mantenedores do sistema.

Web Systems are widely used and accepted due to their advantages over traditional desktop applications. Modernization of existing non-Web software towards the Web, however, is a complex and challenging task due to Legacy System characteristics. Independent Software Vendors are struggling to commence Web Migration because of the involved effort and risk. Through systematic field research and problem analysis, this situation is further analyzed, deriving a set of requirements that represent the effort and risk concerns and are used to assess the state of the art in the field. Existing Web Migration research exhibits gaps concerning dedicated approaches for the initial phase and feasibility of the proposed strategies with limited resources and expertise. This thesis proposes a solution to address the shortcomings above and support Independent Software Vendors to commence Web Migration, focusing on effort and risk. The main idea is to provide a set of dedicated solutions to close the identified gaps in the form of a methodology and a supporting toolsuite that transfer paradigms successfully solving similar problems in other areas of computer science into the Web Migration domain. These solutions constitute the proposed approach called Agile Web Migration for SMEs (AWSM), consisting of methods, tools, principles, and formalisms for reverse engineering, risk management, customer impact control, and migration strategy selection. The thesis describes the research on the devised ideas in the context of a collaboration project with an Independent Software Vendor. Applicability and feasibility of the concepts are demonstrated in several evaluation experiments, integrating empirical user studies and objective measurements. The thesis concludes with an evaluation based on requirements assessment and application of the solutions in the application scenario, and it provides an outlook towards future work.:1 Introduction 2 Requirements Analysis 3 State of the Art 4 Addressing Effort and Risk Concerns in Web Migration 5 AWSM Reverse Engineering Method 6 AWSM Risk Management Method 7 AWSM Customer Impact Control Method 8 Evaluation 9 Conclusion and Outlook / Web-basierte Software-Systeme werden weithin verwendet und akzeptiert aufgrund ihrer Vorteile gegenüber traditionellen Desktopanwendungen. Die Modernisierung von Nicht-Web-Software zu Web-Software stellt jedoch wegen der Charakteristika von Legacy-Systemen eine komplexe und herausfordernde Aufgabe dar. Unabhängigen Softwareproduzenten (Independent Software Vendors) fällt es schwer, Web Migration zu initiieren aufgrund des damit einhergehenden Aufwands und Risikos. Durch systematische Primärerhebungen und Problemanalyse wird diese Situation weitergehend untersucht und eine Reihe von Anforderungen abgeleitet, welche die Aufwands- und Riskobedenken repräsentieren und verwendet werden, um den Stand der Technik in diesem Gebiet zu bewerten. Existierende Web Migration Forschung weist Mängel hinsichtlich von dedizierten Ansätzen für die initiale Phase und der Machbarkeit der vorgeschlagenen Strategien mit begrenzten Ressourcen und begrenzter Expertise auf. Diese Dissertation schlägt eine Lösung für die oben ausgeführten Mängel vor, um unabhängige Softwareproduzenten bei der Initiierung einer Web Migration zu unterstützen, welche sich auf ihre Bedenken bezüglich des Aufwands und Risikos fokussiert. Die Grundidee ist es eine Sammlung von dedizierten Lösungen für die identifizierten Mängel in Form einer Methodologie und einer Reihe von unterstützenden Werkzeugen anzubieten, welche Paradigmen, die erfolgreich ähnliche Probleme in anderen Gebieten der Informatik lösen konnten, in die Web Migration Domäne transferieren. Diese Lösungen ergeben den vorgeschlagenen Ansatz, Agile Web Migration for SMEs (AWSM), welcher aus Methoden, Werkzeugen, Prinzipien und Formalismen für Reverse Engineering, Riskomanagement, Customer Impact Control und Migrationsstrategieauswahl bestehen. Die Dissertation beschreibt die Forschung an den im Rahmen einer Industriekooperation mit einem unabhängigen Softwareproduzenten entwickelten Ideen. Anwendbarkeit und Machbarkeit der Konzepte werden in mehreren Evaluationsexperimenten, welche empirische Nutzerstudien mit objektiven Messungen verbinden, demonstriert. Die Dissertation schließt mit einer bewertenden Evaluation basierend auf den Anforderungen und auf dem Einsatz der Lösungen im Anwendungsszenario, sowie einem Ausblick auf weiterführende Arbeiten.:1 Introduction 2 Requirements Analysis 3 State of the Art 4 Addressing Effort and Risk Concerns in Web Migration 5 AWSM Reverse Engineering Method 6 AWSM Risk Management Method 7 AWSM Customer Impact Control Method 8 Evaluation 9 Conclusion and Outlook