Dissertations / Theses on the topic 'Event-driven Programming'

Nowadays, event processing is becoming the backbone of many applications. Therefore, it is necessary to provide suitable abstractions to properly modularize the concerns that appear in event-driven applications. We identify four categories of languages that support event-driven programming, and identify their shortcomings in achieving modularity in the implementation of applications. We propose gummy modules and their implementation in the GummyJ language as a solution. Gummy modules have well-defined event-based interfaces, and can have a primitive or a composite structure. Composite gummy modules are means to group a set of correlated event processing concerns and restrict the visibility of events among them. We provide an example usage of gummy modules, and discuss their event processing semantics.

A new distributed object-oriented discrete event-driven simulation environment, DODESE, is developed to provide a common framework for simulation model design and implementation. The DODESE can be used to define a simulation including all the simulation objects participating in the simulation while the execution of the simulation can be interactively monitored on DODESE. The DODESE system has combined the strengths of both object-oriented paradigms and data base technology to make computer simulation more powerful and has achieved the goals of object-orientation, distribution, reusability, maintainability and extensibility. The system runs on two Sun workstations concurrently connected by an Ethernet. One of the workstations performs the simulation tasks while the other workstation displays the status of the simulation interactively. Both workstations communicate through the GemStone data base, thus a mechanism is designed for synchronization and concurrency control. The DODESE is implemented using OPAL, GemStone’s data definition and manipulation language, C and Xlib.

Web is constantly evolving, thanks to the 2.0 transition, HTML5 new features and the coming of cloud-computing, the gap between Web and traditional desktop applications is tailing off. Web-apps are more and more widespread and bring several benefits compared to traditional ones. On the other hand reference technologies, JavaScript primarly, are not keeping pace, so a paradim shift is taking place in Web programming, and so many new languages and technologies are coming out. First objective of this thesis is to survey the reference and state-of-art technologies for client-side Web programming focusing in particular on what concerns concurrency and asynchronous programming. Taking into account the problems that affect existing technologies, we finally design simpAL-web, an innovative approach to tackle Web-apps development, based on the Agent-oriented programming abstraction and the simpAL language. == Versione in italiano: Il Web è in continua evoluzione, grazie alla transizione verso il 2.0, alle nuove funzionalità introdotte con HTML5 ed all’avvento del cloud-computing, il divario tra le applicazioni Web e quelle desktop tradizionali va assottigliandosi. Le Web-apps sono sempre più diffuse e presentano diversi vantaggi rispetto a quelle tradizionali. D’altra parte le tecnologie di riferimento, JavaScript in primis, non stanno tenendo il passo, motivo per cui la programmazione Web sta andando incontro ad un cambio di paradigma e nuovi linguaggi e tecnologie stanno spuntando sempre più numerosi. Primo obiettivo di questa tesi è di passare al vaglio le tecnologie di riferimento ed allo stato dell’arte per quel che riguarda la programmmazione Web client-side, porgendo particolare attenzione agli aspetti inerenti la concorrenza e la programmazione asincrona. Considerando i principali problemi di cui soffrono le attuali tecnologie passeremo infine alla progettazione di simpAL-web, un approccio innovativo con cui affrontare lo sviluppo di Web-apps basato sulla programmazione orientata agli Agenti e sul linguaggio simpAL.

Microworlds are visual, 2D grid-based worlds with programmable actors that help ease students into programming. Microworlds have been used as a pedagogical tool for teaching students to program in an object-oriented paradigm for several years now. With the popularity of Android smart phones, creating a pedagogical microworld for Android can help students learn not just Java, OO and event-driven concepts, but also learn to use the Android framework to create concrete, real-world applications. This thesis presents Sofia.Micro, an Android-based pedagogical microworld framework that not only allows Greenfoot-style microworld programs to run on Android, but also adds additional functionalities to microworlds that have not been previously explored, such as built-in shape and physics support, event-driven programming in a microworld context, and allowing for both Greenfoot-style actors and Karel-style actors in the same world.
Master of Science

This document is a master’s thesis analyzing an automated fuel pump management system. In the first chapters we take a general overview of the system and the main problems that we will be facing during the planning and design phases of the project. Later we propose and analyze possible solutions for these problems. Technical system information is revealed in the later chapters. Functional and non functional requirements are discussed along with the main UML diagrams. The research phase of the thesis provides detailed system analysis and software quality reports which later are used to create proposed changes to the system. These changes are analyzed, designed and coded in the final - experimental part of the thesis. The main proposal is to convert the system architecture from flow driven to event driven. This change helps to solve several uncovered architectural problems as well as improve the general quality of the system. These changes are tested and analyzed in the experimental chapter of the thesis and finally the conclusions are made. The main conclusion is that the proposed architectural changes were chosen correctly. This is also supported by the experimental data.

L’utilisation de concepts avancés de programmation concurrente permet de dépasser les inconvénients de l’utilisation de techniques de bas niveau à base de verrous ou de moniteurs. Elle augmente le niveau d’abstraction, libérant les programmeurs d’applications concurrentes d’une focalisation excessive sur des détails. Cependant, avec les approches actuelles, la logique nécessaire à la mise en place de schémas de coordinations complexes est fragmentée en plusieurs points de l’application sous forme de« join patterns », de notifications et de la logique applicative qui crée implicitement des dépendances entre les canaux de communication et donc, indirectement, les « join patterns » (qui définissent ces canaux). Nous présentons JEScala, un langage qui capture les schémas de coordination (d’une application concurrente) d’une manière plus expressive et modulaire, en s’appuyant sur l’intégration fine d’un système d’évènements avancé et des « join patterns ». Nous implémentons des automates finis à partir de « joins » à l’aide de JEScala et introduisons un langage dédié à la définition de ces automates finis permettant d’en obtenir des implémentations plus efficaces. Nous validons notre approche avec des études de cas et évaluons l’efficacité de son exécution. Nous comparons la performance de trois implémentations d’un automate fini. Nous validons enfin l’idée d’un moniteur d’évènements en créant un programme JEScala concurrent à partir d’un découpage d’un programme séquentiel
The advanced concurrency abstractions provided by the Join calculus overcome the drawbacks of low-level techniques such as locks and monitors. They rise the level of abstraction, freeing programmers that implement concurrent applications from the burden of concentrating on low-level details. However, with current approaches the coordination logic involved incomplex coordination schemas is fragmented into several pieces including join patterns, data emissions triggered in different places of the application, and the application logic that implicitly creates dependencies among channels, hence indirectly among join patterns. We present JEScala, a language that captures coordination schemas in a more expressive and modular way by leveraging a seamless integration of an advanced event system with join abstractions. We implement Joins-based state machines using JEScala and introduce a domain specific language for finite state machines that make faster alternative implementations possible. We validate our approach with case studies and we provide a first performance assessment. We compare the performance of three different implementations of a finite state machine. Finally, we validate the idea of constructing a concurrent JEScala program by using the parts of a sequential Event-Based program in combination with an event monitor, a component that synchronizes handling of multiple events

Quando si parla di architetture di controllo in ambito Web, il Modello ad Eventi è indubbiamente quello più diffuso e adottato. L’asincronicità e l’elevata interazione con l’utente sono caratteristiche tipiche delle Web Applications, ed un architettura ad eventi, grazie all’adozione del suo tipico ciclo di controllo chiamato Event Loop, fornisce un'astrazione semplice ma sufficientemente espressiva per soddisfare tali requisiti. La crescita di Internet e delle tecnologie ad esso associate, assieme alle recenti conquiste in ambito di CPU multi-core, ha fornito terreno fertile per lo sviluppo di Web Applications sempre più complesse. Questo aumento di complessità ha portato però alla luce alcuni limiti del modello ad eventi, ancora oggi non del tutto risolti. Con questo lavoro si intende proporre un differente approccio a questa tipologia di problemi, che superi i limiti riscontrati nel modello ad eventi proponendo un architettura diversa, nata in ambito di IA ma che sta guadagno popolarità anche nel general-purpose: il Modello ad Agenti. Le architetture ad agenti adottano un ciclo di controllo simile all’Event Loop del modello ad eventi, ma con alcune profonde differenze: il Control Loop. Lo scopo di questa tesi sarà dunque approfondire le due tipologie di architetture evidenziandone le differenze, mostrando cosa significa affrontare un progetto e lo sviluppo di una Web Applications avendo tecnologie diverse con differenti cicli di controllo, mettendo in luce pregi e difetti dei due approcci.

Les machines multicœurs actuelles utilisent une architecture à Accès Mémoire Non-Uniforme (Non-Uniform Memory Access - NUMA). Dans ces machines, les cœurs sont regroupés en nœuds. Chaque nœud possède son propre contrôleur mémoire et est relié aux autres nœuds via des liens d'interconnexion. Utiliser ces architectures à leur pleine capacité est difficile : il faut notamment veiller à éviter les accès distants (i.e., les accès d'un nœud vers un autre nœud) et la congestion sur les bus mémoire et les liens d'interconnexion. L'optimisation de performance sur une machine NUMA peut se faire de deux manières : en implantant des optimisations ad-hoc au sein des applications ou de manière automatique en utilisant des heuristiques. Cependant, les outils existants fournissent trop peu d'informations pour pouvoir implanter efficacement des optimisations et les heuristiques existantes ne permettent pas d'éviter les problèmes de congestion. Cette thèse résout ces deux problèmes. Dans un premier temps nous présentons MemProf, le premier outil d'analyse permettant d'implanter efficacement des optimisations NUMA au sein d'applications. Pour ce faire, MemProf construit des flots d'interactions entre threads et objets. Nous évaluons MemProf sur 3 machines NUMA et montrons que les optimisations trouvées grâce à MemProf permettent d'obtenir des gains de performance significatifs (jusqu'à 2.6x) et sont très simples à implanter (moins de 10 lignes de code). Dans un second temps, nous présentons Carrefour, un algorithme de gestion de la mémoire pour machines NUMA. Contrairement aux heuristiques existantes, Carrefour se concentre sur la réduction de la congestion sur les machines NUMA. Carrefour permet d'obtenir des gains de performance significatifs (jusqu'à 3.3x) et est toujours plus performant que les heuristiques existantes
Modern multicore systems are based on a Non-Uniform Memory Access (NUMA) design. In a NUMA system, cores are grouped in a set of nodes. Each node has a memory controller and is interconnected with other nodes using high speed interconnect links. Efficiently exploiting such architectures is notoriously complex for programmers. Two key objectives on NUMA multicore machines are to limit as much as possible the number of remote memory accesses (i.e., accesses from a node to another node) and to avoid contention on memory controllers and interconnect links. These objectives can be achieved by implementing application-level optimizations or by implementing application-agnostic heuristics. However, in many cases, existing profilers do not provide enough information to help programmers implement application-level optimizations and existing application-agnostic heuristics fail to address contention issues. The contributions of this thesis are twofold. First we present MemProf, a profiler that allows programmers to choose and implement efficient application-level optimizations for NUMA systems. MemProf builds temporal flows of interactions between threads and objects, which help programmers understand why and which memory objects are accessed remotely. We evaluate MemProf on Linux on three different machines. We show how MemProf helps us choose and implement efficient optimizations, unlike existing profilers. These optimizations provide significant performance gains (up to 2.6x), while requiring very lightweight modifications (10 lines of code or less). Then we present Carrefour, an application-agnostic memory management algorithm. Contrarily to existing heuristics, Carrefour focuses on traffic contention on memory controllers and interconnect links. Carrefour provides significant performance gains (up to 3.3x) and always performs better than existing heuristics

Il termine Internet of Things viene spesso utilizzato per definire oggetti intelligenti, servizi, and applicazioni connessi attraverso Internet. Uno studio redatto da Cisco afferma che la crescita del numero e della varietà di devices da cui collezionare dati è estremamente rapida. Aumentando il numero di devices aumenta conseguentemente anche la complessità, quindi, ci si trova ad affrontare problemi tra i quali: mancanza di modularità e riusabilità, difficoltà nelle fasi di test, manutenzione e rilascio. La Programmazione Aggregata fornisce un'alternativa ai metodi di sviluppo software tradizionali, che semplifica drammaticamente progettazione, creazione, e manutenzione di sistemi IoT complessi. Con questa tecnica, l'unità base di computazione non è più un singolo device ma una collezione cooperativa di devices. Questa tesi descrive la progettazione e sviluppo di una Piattaforma per Programmazione Aggregata basata su microservizi nel Cloud. A differenza del modello distribuito della Programmazione Aggregata, il Cloud Computing rappresenta un'ulteriore opportunità per la costruzione di sistemi scalabili e può essere pensato come una strategia alternativa di esecuzione dove le computazioni sono per l'appunto eseguite su Cloud. Per poter ottenere il massimo dalle tipiche caratteristiche di scalabilità ed affidabilità fornite dal modello Cloud occorre adottare un'architettura adeguata. Questo lavoro descrive come poter servirsi dell'architettura a microservizi costruendo l'infrastruttura richiesta per la comunicazione tra processi dalle fondamenta. Data la maggiore complessità tecnologica delle architetture a microservizi, l'elaborato descrive come adottare un approccio a "container" alleviando le difficoltà di gestione attraverso un container orchestrator.

O crescimento explosivo no número de usuários de Internet levou arquitetos de software a reavaliarem questões relacionadas à escalabilidade de serviços que são disponibilizados em larga escala. Projetar arquiteturas de software que não apresentem degradação no desempenho com o aumento no número de acessos concorrentes ainda é um desafio. Neste trabalho, investigamos o impacto do sistema operacional em questões relacionadas ao desempenho, paralelização e escalabilidade de jogos interativos multi-usuários. Em particular, estudamos e estendemos o jogo interativo, multi-usuário, QuakeWorld, disponibilizado publicamente pela id Software sob a licença GPL. Criamos um modelo de paralelismo para a simulação distribuída realizada pelo jogo e o implementamos no servidor do QuakeWorld com adaptações que permitem que o sistema operacional gerencie de forma adequada a execução da carga de trabalho gerada.
The explosive growth in the number of Internet users made software architects reevaluate issues related to the scalability of services deployed on a large scale. It is still challenging to design software architectures that do not experience performance degradation when the concurrent access increases. In this work, we investigate the impact of the operating system in issues related to performance, parallelization, and scalability of interactive multiplayer games. Particularly, we study and extend the interactive, multiplayer game QuakeWorld, made publicly available by id Software under GPL license. We have created a new parallelization model for Quake\'s distributed simulation and implemented that model in QuakeWorld server with adaptations that allows the operating system to manage the execution of the generated workload in a more convenient way.

Cette thèse traite des performances des serveurs de données en multi-cœur. Plus précisément nous nous intéressons au passage à l'échelle avec le nombre de cœurs. Dans un premier temps, nous étudions le fonctionnement interne d'un support d'exécution événementiel multi-cœur. Nous montrons tout d'abord que le faux-partage ainsi que les mécanismes de communications inter-cœurs dégradent fortement les performances et empêchent le passage à l'échelle des applications. Nous proposons alors plusieurs optimisations pour pallier ces comportements. Dans un second temps, nous comparons les performances en multi-cœur de trois serveurs Web chacun représentatif d'un modèle de programmation. Nous remarquons que les différences de performances observées entre les serveurs varient lorsque le nombre de cœurs augmente. Après une analyse approfondie des performances observées, nous identifions la cause de la limitation du passage à l'échelle des serveurs étudiés. Nous présentons une proposition ainsi qu'un ensemble de pistes pour lever cette limitation.

Dissertação de Mestrado em Engenharia Informática apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Recently, event-oriented programming frameworks have surfaced as a solution to highly scalable network applications. This model as been adopted under many languages resulting in frameworks such as Node.js, Gevent and EventMachine. These frameworks are capable of handling many concurrent requests by using asynchronous IO. However, in order to make use all available cores, parallelism is exploited by creating multiple instances of the same application. Under this solution instances don’t share memory making synchronization mechanisms required. The same problem applies when using the actor model for concurrency. The EVE framework provides support for event-oriented programming under a shared-memory model. It encompasses the EVE language definition, its compiler and a runtime system capable of executing the resulting applications. Using our model, the programmer divides the application logic into tasks and each task indicates what variables it can access. The runtime schedules compatible tasks to multiple cores using a work-stealing algorithm for load balancing. In this work, we present a formal description of the language and it’s runtime, including their operational semantics. Our benchmarks indicate that our solution delivers the best performance on IO heavy problems when compared to existing of-the-shelf solutions and performance comparable to the state-of-the-art architectures for CPU-bounded applications.

碩士
國立中央大學
資訊工程學系
107
Now a day, most of programs having UI interfaces. Whether it is a website program or an operating system, the process of the programs is determined by the user's operating. So that, the interaction between the program and the user is more and more important. The design of such programs is often using event-driven design. Event-driven programming is a common programming paradigm in which the flow of program is determined by the event such as user motions or messages from other programs. How difficult it is to design the event-driven programs is also depending on the programming language. Programming languages like C#, JAVA, PYTHON, etc., are easier to design event-driven programs because of the supporting of language itself. However, one of widely using language: C language, because of the lack of language-based support, can only design event-driven programs by the experience from designers. This research will present a tool which is called “C Event Dispatcher”(CED) to assist programmers in writing event-driven programs in C language. The feature of CED tool is that it use different way to trigger the event handler. Without using timeout and signal, it use conditional expression to trigger the handler, giving user more flexibility to design event-driven program. User can use the mechanism of conditional expression to monitor a event variable, calling the event handler depending on the condition of the event variable. The CED tool also support the publish–subscribe pattern, increasing the flexibility of event-driven architecture and the maintainability of the code. The finite-state machine built by CED tool can dynamically decrease and increase the states in the finite-state machine. This advantage is suitable for using on the embedded system. It can make the embedded system more flexible and maintainable.

碩士
國立中央大學
資訊工程研究所
84
Most systems for developing educational software do not provide a good language or mechanism for establishing student model, designing teaching strategy and simulating learning companion in intelligent tutoriing systems (ITSs). It is very inconvenient and difficult for users while designing such a complex 　system. Agent-Oriented Programming (AOP) is a new programming paradigm that helps design large systems like ITSs, so we dsigned a programming language named CAROL5, and we combine event-driven, object-base and rule-base mechanisms to achieve the purpose of facilitating users to design AOP applications.　 　　In CAROL5, we preserve the rule-based programming style inherited from its pervious version, CAROL4, and delegation for resource sharing between objects, instead of inheritance.There is no difference between the state and behavior of an object, they are both variables of the object now. Event Sending & Handling Mechanism is a new feature added to the language. An agent can check his state continuously. When some condition is satisfied, the event will be triggered and broadcast to other agents. When other agents receive these events, they may respond, changing its state or other agents' states. This may, in tern, trigger other events and cause a chain reactions. The purpose is to allow agents act continuously.We hope we can transfer this system to network environment in the futuer, to achieve the goal of having the ability to write network agent applications. 　　In this thesis, we give a detail description of the method, syntax and semantics of CAROL5, and various examples are illustrated. The C++ implementation of the CAROL5 interpreter is also introduced. Combining the event-driven, object-base and rule-base programming style, CAROL5 is a flexible and powerful language that support the development of AOP applications.