Thesis (Ph. D.)--State University of New York at Binghamton, Department of Computer Science, 2006. / Includes bibliographical references (leaves 89-93).

Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Sept. 8, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Computing Science, University of Alberta." Includes bibliographical references.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Oct. 2, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Computing Science, University of Alberta." Includes bibliographical references.

<p>Skriptspråk har under det senaste decenniet fått en ökad spridning, både gällande användare</p><p>och gällande användningsområden. Från att huvudsakligen ha använts till enklare dagliga</p><p>administratörsuppgifter används idag skriptspråken inom många områden där tidigare enbart</p><p>systemspråk var ett alternativ. Denna uppsats undersöker och granskar fem skriptspråk: PHP,</p><p>Perl, Ruby, Tcl och PostScript. Målet är att undersöka språkens egenskaper och se på</p><p>skillnader språken emellan. Vi jämför också skriptspråken mot systemspråket C, som dock</p><p>inte granskas för sig. Vi utför ett test där quicksort-algoritmen används för att sortera ett antal</p><p>element som läses in från fil. Ett testskript skrivs i varje språk, och dess effektivitet och</p><p>expressivitet jämförs.</p><p>Vi kommer i denna uppsats fram till att definitionen för skriptspråk, och det som skiljer</p><p>skriptspråk från systemspråk, är skriptspråkens avsaknad av ett separat kompileringssteg. En</p><p>annan viktig aspekt är skriptspråkens användning av dynamisk typbindning för variabler. De</p><p>tester vi gjort visar att inget av skriptspråken kan mäta sig med systemspråket C vad gäller</p><p>exekveringstid, däremot är de bättre gällande expressivitet. Av skriptspråken är Perl det språk</p><p>som är snabbast och PostScript det språk som är långsammast.</p> / <p>During the last decade, scripting languages have seen an increase in both number of users and</p><p>areas of development. Earlier, scripting languages were mainly used for everyday system</p><p>administration tasks. Nowadays, scripting languages are used in areas where previously only</p><p>system languages were an alternative. In this dissertation, five scripting languages are</p><p>compared and reviewed. The languages are: PHP, Perl, Ruby, Tcl, and PostScript. The goal is</p><p>to examine characteristics of the languages and illustrate the differences between them. We</p><p>also compare the scripting languages against the system language C, which is not examined in</p><p>this dissertation. We perform a test where the quicksort algorithm is used to sort a number of</p><p>elements which are read from file. A test script is written in every language, and their</p><p>efficiency and expressiveness are compared.</p><p>In this dissertation we come to the conclusion that the definition of scripting languages, and</p><p>the main difference between scripting languages and system languages, is the absence of a</p><p>separate compiling stage for scripting languages. We also consider the use of dynamic typing</p><p>regarding variables to be an important aspect of scripting languages. The tests have shown</p><p>that scripting languages can not compete with the system language C regarding efficiency of</p><p>execution, but the scripting languages have a higher level of expressiveness. Perl is fastest</p><p>among the scripting languages and PostScript is the slowest.</p>

[pt] Expressões regulares são um formalismo utilizado para descrever linguagens regulares e compõem a base de diversas bibliotecas de casamento de padrão. No entanto, existem determinados padrões úteis que são complexos ou impossíveis de serem descritos com expressões regulares puras. Devido a essas limitações, linguagens de script modernas disponibilizam bibliotecas de casamento de padrões baseadas em regexes, isto é, extensões de expressões regulares compostas, principalmente, por construções ad-hoc que focam em problemas específicos. Apesar de serem muito úteis na prática, os regexes possuem implementações complexas e distantes do formalismo original de expressões regulares. Parsing Expression Grammars (PEG) são uma alternativa formal para reconhecer padrões e possuem mais expressividade que expressões regulares sem necessitar de contruções ad-hoc. O objetivo deste trabalho é estudar formas de conversão de regexes para PEGs. Para isso, estudamos as implementações atuais de regexes e mostramos a conversão de algumas construções para PEGs. Por fim, apresentamos uma implementação da conversão de regexes para PEGs para a linguagem Lua. / [en] Regular expressions are a formalism used to describe regular languages and form the basis of several pattern-matching libraries. However, many interesting patterns either are difficult to describe or cannot be described by pure regular expressions. Because of these limitations, modern scripting languages have pattern matching libraries based on regexes, ie, extensions of regular expressions mainly composed by a set of ad-hoc constructions that focus on specific problems. Although very useful in practice, these implementations are complex and distant from the original formalism of regular expressions. Parsing Expression Grammars (PEG) are a formal alternative to recognize patterns and it is much more expressive than pure regular expressions and does not need use ad-hoc constructions. The goal of this work is to study the convertion of regexes to PEGs. To accomplish this task, we studied the current implementations of regexes and show how to convert some constructions to PEGs. Finally, we present an implementation that convert regexes to PEGs for the Lua language.

The subject of this thesis is a qualitative analysis of the usability of three contemporary programming languages: Perl, Python, and Tcl. The relative usability of these languages was assessed by implementing two representative applications — a paint program and a chat program — in all three languages; using PSP to collect data on program development; and then comparing development times, defect counts, and defect fix times. Overall, Python was the easiest of the three languages to use, especially for new users. Perl is the hardest, and Tcl is somewhere between. Specifically, Perl's basic language constructs are the hardest to learn and to use. Python's are the easiest. Tcl's are closer to Python's. Python's and Tcl's mechanisms for supporting OO are much easier to learn for new users than Perl's. Python's Tk libraries are easier to use than Perl's and Tcl's. Tcl's [Incr Widget] (megawidgets) library is by far the hardest to master. Perl's Tk library is somewhere in between. Perl's I/O and Socket libraries are much harder to use than Python's and Tcl's. The primary recommendations of this study are as follows: For Perl, a better OO support will reduce a significant number of OO-related defects, especially to new users. For Tcl, Tcl's [Incr Tcl] megawidget library should wrap the standard raw Tk widgets into [Incr Tk] classes, to prevent a significant number of defects from mixture uses of raw Tk widgets and [incr Tk] megawidgets classes. Tcl's eventloop mechanism is a good model for handling non-blocking sockets and I/Os. Both Perl and Python should also provide such an easy model.

[pt] Um cenário comum atualmente é o de aplicações desenvolvidas usando duas linguagens de programação a fim de otimizar partes onde o desempenho é crítico e permitir extensibilidade através de scripts escritos pelo usuário. Há várias formas de se obter esse tipo de interoperabilidade; idealmente, entretanto, uma linguagem deve prover uma interface de acesso externo (foreign language interface, FLI) que permita ao programador receber e enviar tanto chamadas como dados para outra linguagem. Este trabalho discute as principais questões envolvendo o projeto de APIs para integração de ambientes de execução de linguagens em aplicações C. Apresentamos os principais problemas enfrentados na interação entre código executando em um ambiente com características inerentemente dinâmicas como o de uma linguagem de script com código C. Comparamos aqui as abordagens empregadas por cinco linguagens no tratamento da comunicação entre os espaços de dados de C e do ambiente de execução embutido e as conseqüências destas abordagens no gerenciamento de memória, bem como no compartilhamento de código entre a aplicação C e o da linguagem de script. Ilustramos as diferenças das APIs destas linguagens e o impacto destas no código resultante de uma aplicação C através de um estudo de caso. Diferentes linguagens de script são embutidas como plugins de uma mesma biblioteca, que por sua vez expõe a aplicações clientes uma API genérica de scripting. Assim, o código de cada plugin permite observar de forma clara e isolada os procedimentos adotados em cada linguagem para chamada de funções, registro de funçoes C e conversão de dados entre os ambientes. / [en] Applications written in two programming languages, in order to optimize parts where performance is critical or to obtain extensibility through userwritten scripts, are commonplace nowadays. There are several ways to obtain this kind of interoperability; ideally, however, a language should provide a foreign language interface (FLI), allowing the programmer to send and receive both data and function calls to the external language. This work discusses the main issues involving the design of APIs for the integration of language environments within C applications. We present the main problems faced in the interaction between code executed in an environment with inherently dynamic characteristics such as a scripting language and C code. We compare the approaches employed by five languages when handling communication between the data spaces of C and the embedded runtime environment and the consequences of these approaches in memory management, as well as sharing of code between the C application and that from the scripting language. We illustrate the differences of the APIs of those languages and their impact in the resulting code of a C application through a case study. Different scripting languages were embedded as plugins for a library, which on its turn exposes to client applications a generic scripting API. This way, the code of each plugin allows us to observe in a clear and isolated way the procedures adopted by each language for function calls, registration of C functions and conversion of data between the environments.

Skriptspråk har under det senaste decenniet fått en ökad spridning, både gällande användare och gällande användningsområden. Från att huvudsakligen ha använts till enklare dagliga administratörsuppgifter används idag skriptspråken inom många områden där tidigare enbart systemspråk var ett alternativ. Denna uppsats undersöker och granskar fem skriptspråk: PHP, Perl, Ruby, Tcl och PostScript. Målet är att undersöka språkens egenskaper och se på skillnader språken emellan. Vi jämför också skriptspråken mot systemspråket C, som dock inte granskas för sig. Vi utför ett test där quicksort-algoritmen används för att sortera ett antal element som läses in från fil. Ett testskript skrivs i varje språk, och dess effektivitet och expressivitet jämförs. Vi kommer i denna uppsats fram till att definitionen för skriptspråk, och det som skiljer skriptspråk från systemspråk, är skriptspråkens avsaknad av ett separat kompileringssteg. En annan viktig aspekt är skriptspråkens användning av dynamisk typbindning för variabler. De tester vi gjort visar att inget av skriptspråken kan mäta sig med systemspråket C vad gäller exekveringstid, däremot är de bättre gällande expressivitet. Av skriptspråken är Perl det språk som är snabbast och PostScript det språk som är långsammast. / During the last decade, scripting languages have seen an increase in both number of users and areas of development. Earlier, scripting languages were mainly used for everyday system administration tasks. Nowadays, scripting languages are used in areas where previously only system languages were an alternative. In this dissertation, five scripting languages are compared and reviewed. The languages are: PHP, Perl, Ruby, Tcl, and PostScript. The goal is to examine characteristics of the languages and illustrate the differences between them. We also compare the scripting languages against the system language C, which is not examined in this dissertation. We perform a test where the quicksort algorithm is used to sort a number of elements which are read from file. A test script is written in every language, and their efficiency and expressiveness are compared. In this dissertation we come to the conclusion that the definition of scripting languages, and the main difference between scripting languages and system languages, is the absence of a separate compiling stage for scripting languages. We also consider the use of dynamic typing regarding variables to be an important aspect of scripting languages. The tests have shown that scripting languages can not compete with the system language C regarding efficiency of execution, but the scripting languages have a higher level of expressiveness. Perl is fastest among the scripting languages and PostScript is the slowest.

[pt] Inchaço de memória e um problema que ocorre quando a memória consumida por um programa excede a expectativa do programador. Em muitos casos, o inchaço de memória prejudica o desempenho ou, até mesmo, interrompe a execução de aplicações. Detectar e consertar inchaços de memória é uma tarefa difícil para programadores e, portanto, eles costumam usar ferramentas para identificar e consertar problemas desta natureza. Nas últimas duas décadas, muitos trabalhos e ferramentas foram desenvolvidos com o intuito de ajudar programadores a abordar problemas de inchaço de memória, entre eles perfiladores de memória. Apesar de perfiladores de memória terem sido muito estudados nos últimos anos, existe uma lacuna em relação a linguagens de script. Nessa dissertação, nós estudamos perfiladores de memória para linguagens de script. Primeiro, nos propomos uma classificação que divide as ferramentas em manual e automática baseada em como elas são usadas pelos programadores. Em seguida, após estudar ferramentas disponíveis em três linguagens de script diferentes, nós experimentamos algumas das técnicas estudadas ao construir dois perfiladores de memória automáticos para ajudar programadores Lua a resolver inchaços de memória. Finalmente, nós avaliamos ambas as ferramentas com relação a facilidade de integração ao programa, a utilidade dos relatórios para o entendimento de programas desconhecidos e para a localização de inchaços de memória e ao custo de desempenho que elas geram. / [en] Memory bloat is a software problem that happens when the memory consumption of a program exceeds the programmer s expectations. In many cases, memory bloat hurts performance or even crashes applications. Detecting and fixing memory bloat problems is a difficult task for programmers and, thus, they usually need tools to identify and fix these problems. The past two decades produced an extensive research and many tools to help programmers tackle memory bloat, including memory profilers. Although memory profilers have been largely studied in the last years, there is a gap regarding scripting languages. In this thesis, we study memory profilers in scripting languages. First, we propose a classification in which we divide memory profilers in manual and automatic, based on how the programmer uses the memory profiler. Then, after reviewing memory profilers available in three different scripting languages, we experiment some of the studied techniques by implementing two automatic memory profilers to help Lua programmers deal with memory bloat. Finally, we evaluate our tools regarding how easy it is to incorporate them to a program, how useful their reports are to understand an unknown program and track memory bloats, and how much overhead they impose.

This thesis investigates two different web server solutions. One is a commercial, proprietary solution known as the Windows solution that consists of Windows Server 2003, IIS and ASP. The other is a free, open source solution consisting of FreeBSD, Apache and PHP. The both solutions had the database MySQL as a common component. The hypothesis that was used in this investigation is as follows: IIS on Windows Server is not better than Apache on FreeBSD for e-commerce systems. To answer the hypothesis two empirical comparisons were conducted. One was a response time experiment testing two symmetrical web shops developed for the both solutions. For this response time test a stress test application was developed. The second comparison was a case study in the ease of installation of the two different solutions. The third empirical research method was a survey that was conducted among Swedish web hotel administrators. The survey identifies various factors that play a part when choosing one of the solutions. Open source users prefer performance, security and costs of software while Windows users prefer required knowledge, usability and compatibility. By analysing our result it is shown that the hypothesis is verified proving that an open source solution reports better performance because it has lower response times than the Windows solution. The results from the case study show that Windows is the easiest solution to install. / Den här uppsatsen undersöker två olika webbservrar lösningar. En är kommersiell patentskyddad lösning känd som Windows lösningen som består av Windows Server 2003, IIS och ASP. Den andra lösningen är en gratis open source lösning som består av FreeBSD, Apache och PHP. Båda lösningarna har databasen MySQL som en jämensam komponent. Hypotesen som användes i denna forskning är; IIS på Windows Server är inte bättre än Apache på FreeBSD för e-handel system. För att kunna besvara hypotesen gjordes två empirisk jämförelsen. En var respons tid experiment som testade två symmetriska webb shops som var utvecklad av oss för bägge lösningarna. För detta experiment utvecklades en stress test program. Den andra jämförelsen var en fallstudie i lätthet av installation av dessa två lösningar. Den tredje forsknings metoden är en undersökning bland svensk webb hotell administratörer. Undersökningen identifierar olika faktorer som spelar roll när man väljer en av lösningarna. Open source användare föredrar prestanda, säkerhet och kostnad av mjukvara medan Windows användare föredrar obligatorisk kunskap, användbarhet och jämförbarhet. Genom analys av våra resultat har vi visat att vår hypotes är verifierad och detta bevisar att open source lösningen har bättre prestanda genom att den har lägre respons tid än Windows lösningen. Resultatet av fallstudien visar att Windows är lättare att installera.