Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Computer Science." Includes bibliographical references (p. 110-113).

This research combines the methodology proposed in Axiomatic Design Theory (ADT) with a service oriented decomposition approach for systematic development of Service Oriented Architecture compliant systems. A previous study had applied ADT to component oriented development where simultaneous specification and decomposition of models related to requirements, design, product domain, and components were supported. Recently, Web services have gained popularity and they became a more desired alternative to components. This research sets the foundation for service-oriented modeling and development with ADT support through enhancing the component oriented work conducted before. The goal is to be able to consider customer needs viewed in the domain context, together with the requirements and design so that efficient development can take place based on existing Web services. The system under development is viewed as a hierarchy of process models where leaf-level processes correspond to Web services.

Web-based service providers have long been required to deliver high quality services in accordance with standards and customer requirements. Increasingly, however, providers are required to think beyond service quality and develop a deeper understanding of their customers’ Quality of Experience (QoE). Whilst models exist that assess the QoE of Web Application, significant challenges remain in defining QoE factors from a Web engineering perspective, as well as mapping between so called ‘objective’ and ‘subjective’ factors of relevance. Specifically, the following challenges are considered as general fundamental problems for assessing QoE: (1) Quantifying the relationship between QoE factors; (2) predicting QoE as well as dealing with the limited data available in relation to subjective factors; (3) optimising and controlling QoE; and (4) perceiving QoE. In response, this research presents a novel model, called QoEWA (and associated software instantiation) that integrates factors through Key Performance Indicators (KPIs) and Key Quality Indicators (KQIs). The mapping is incorporated into a correlation model that assesses QoE, in particular, that of Web Application, with a consideration of defining the factors in terms of quality requirements derived from web architecture. The data resulting from the mapping is used as input for the proposed model to develop artefacts that: quantify, predict, optimise and perceive QoE. The development of QoEWA is framed and guided by Design Science Research (DSR) approach, with the purpose of enabling providers to make more informed decisions regarding QoE and/or to optimise resources accordingly. The evaluation of the designed artefacts is based on a build-and-evaluate cycle that provides feedback and a better understanding of the utilised solutions. The key artefacts are developed and evaluated through four iterations: Iteration 1 utilises the Actual Versus-Target approach to quantify QoE, and applies statistical analysis to evaluate the outputs. Iteration 2: utilises a Machine Learning (ML) approach to predict QoE, and applies statistical tests to compare the performance of ML algorithms. Iteration 3 utilises the Multi-Objective Optimisation (MOO) approach to optimise QoE and control the balance between resources and user experience. Iteration 4 utilises the Agent-Based Modelling approach to perceive and gain insights into QoE. The design of iteration 4 is rigorously tested using verified and validated models.

The proliferation of services on the web is leading to the formation of service ecosystems wherein services interact with one another in ways not foreseen during their development or deployment. This means that over its lifetime, a service is likely to be reused across multiple interactions, such that in each of them a different interface is required from it. Implementing, testing, deploying, and maintaining adapters to deal with this multiplicity of required interfaces can be costly and error-prone. The problem is compounded in the case of services that do not follow simple request-response interactions, but instead engage in conversations comprising arbitrary patterns of message exchanges. A key challenge in this setting is service mediation: the act of retrofitting existing services by intercepting, storing, transforming, and (re-)routing messages going into and out of these services so they can interact in ways not originally foreseen. This thesis addresses one aspect of service mediation, namely service interface adaptation. This problem arises when the interface that a service provides does not match the interface that it is expected to provide in a given interaction. Specifically, the thesis focuses on the reconciliation of mismatches between behavioural interfaces, that is, interfaces that capture ordering constraints between message exchanges. We develop three complementary proposals. Firstly, we propose a visual language for specifying adapters for conversational services. The language is based on a an algebra of operators that are composed to define links between provided-required interfaces. These expressions are fed into an execution engine that intercepts, buffers, transforms and forwards messages to enact the adapter specification. Secondly, we endow such adapter specifications with a formal semantics defined in terms of Petri nets. The formal semantics is used to statically check the correctness of adapter specifications. Finally, we propose an alternative approach to service interface adaptation that does not require hard-wired links between provided and required interfaces. This alternative approach is based on the definition of mapping rules between message types, and is embodied in an adaptation machine. The adaptation machine sits between pairs of services and manipulates the exchanged messages according to a repository of mapping rules. The adaptation machine is also able to detect deadlocks and information loss at runtime.

Service-oriented computing is a popular technology that facilitates the development of large-scale distributed systems. However, the modular composition and flexible coordination of such applications still remains challenging for the following reasons: 1) the services are provided as loosely coupled black boxes that only expose their interfaces to the environment; 2) interacting services are not usually known in advance: web services are dynamically chosen to fulfil certain roles and are often replaced by services with a similar functionality; 3) the nature of the service-based application is decentralised. Loose coupling of web services is often lost when it comes to the construction of an application from services. The reason is that the object-oriented paradigm, which is widely used in the implementation of web services, does not provide a mechanism for service interface self-tuning. As a result, it negatively impacts upon the interoperability of web services. In this dissertation we present a formal method for automatic service configuration in the presence of subtyping, polymorphism, and flow inheritance. This is a challenging problem. On the one hand, the interface description language must be flexible enough to maintain service compatibility in various contexts without any modification to the service itself. On the other hand, the composition of interfaces in a distributed environment must be provably consistent. Our method is based on constraint satisfaction and Boolean satisfiability. First, we define a language for specifying service interfaces in a generic form, which is compatible with a variety of contexts. The language provides support for parametric polymorphism, Boolean variables, which are used to control dependencies between any elements of interface collections, and flow inheritance using extensible records and variants. We implemented the method as a constraint satisfaction solver. In addition to this, we present a protocol for interface configuration. It specifies a sequence of steps that leads to the generation of context-specific service libraries from generic services. Furthermore, we developed a toolchain that performs a complete interface configuration for services written in C++. We integrated support for flexible interface objects (i.e. objects that can be transferred in the application along with their structural description). Although the protocol relies solely on interfaces and does not take behaviour concerns into account, it is capable of finding discrepancies between input and output interfaces for simple stateful services, which only perform message synchronisation. Two running examples (a three buyers use-case and an image processing application) are used along the way to illustrate our approach. Our results seem to be useful for service providers that run their services in the cloud. The reason is twofold. Firstly, interfaces and the code behind them can be generic as long as they are sufficiently configurable. No communication between service designers is necessary in order to ensure consistency in the design. Instead, the interface correspondence in the application is ensured by the constraint satisfaction algorithm, which we have already designed. Secondly, the configuration and compilation of every service are separated from the rest of the application. This prevents source code leaks in proprietary software which is running in the cloud.

Les bibliothèques numériques sont des systèmes d'information complexes stockant des ressources numériques (par exemple, texte, images, sons, audio), ainsi que des informations sur les ressources numériques ou non-numériques; ces informations sont appelées des métadonnées. Nous proposons un modèle de données pour les bibliothèques numériques permettant l'identification des ressources, l’utilisation de métadonnées et la réutilisation des ressources stockées, ainsi qu’un langage de requêtes pour l’interrogation de ressources. Le modèle que nous proposons est inspiré par l'architecture du Web, qui forme une base solide et universellement acceptée pour les notions et les services attendus d'une bibliothèque numérique. Nous formalisons notre modèle comme une théorie du premier ordre, afin d’exprimer les concepts de bases de la bibliothèque numérique, sans aucune contrainte technique. Les axiomes de la théorie donnent la sémantique formelle des notions du modèle, et en même temps fournissent une définition de la connaissance qui est implicite dans une bibliothèque numérique. La théorie est traduite en un programme Datalog qui, étant donnée une bibliothèque numérique, permet de la compléter efficacement avec les connaissances implicites. Le but de notre travail est de contribuer à la technologie de gestion des informations des bibliothèques numériques. De cette façon, nous pouvons montrer la faisabilité théorique de notre modèle, en montrant qu'il peut être efficacement appliqué. En outre, nous démontrons la faisabilité pratique du modèle en fournissant une traduction complète du modèle en RDF et du langage de requêtes en SPARQL.Nous fournissons un calcul sain et complet pour raisonner sur les graphes RDF résultant de la traduction. Selon ce calcul, nous prouvons la correction de ces deux traductions, montrant que les fonctions de traduction préservent la sémantique de la bibliothèque numérique et de son langage de requêtes. / Digital Libraries are complex information systems, storing digital resources (e.g., text, images, sound, audio), as well as knowledge about digital or non-digital resources; this knowledge is referred to as metadata. We propose a data model for digital libraries supporting resource identification, use of metadata and re-use of stored resources, as well as a query language supporting discovery of resources. The model that we propose is inspired by the architecture of the Web, which forms a solid, universally accepted basis for the notions and services expected from a digital library. We formalize our model as a first-order theory, in order to be able to express the basic concepts of digital libraries without being constrained by any technical considerations. The axioms of the theory give the formal semantics of the notions of the model, and at the same time, provide a definition of the knowledge that is implicit in a digital library. The theory is then translated into a Datalog program that, given a digital library, allows to efficiently complete the digital library with the knowledge implicit in it. The goal of our research is to contribute to the information management technology of digital libraries. In this way, we are able to demonstrate the theoretical feasibility of our digital library model, by showing that it can be efficiently implemented. Moreover, we demonstrate our model’s practical feasibility by providing a full translation of the model into RDF and of the query language into SPARQL. We provide a sound and complete calculus for reasoning on the RDF graphs resulting from translation. Based on this calculus, we prove the correctness of both translations, showing that the translation functions preserve the semantics of the digital library and of the query language.

Today, web sites are important communication channels that reach a wide group of people. Measuring the effectiveness of these web-sites has become a key issue for researchers as well as practitioners. However, there is no consensus on how to define web site effectiveness and which dimensions need to be used for the evaluation of these web sites. This problem is more noteworthy for information driven web sites like academic web sites. There is limited academic literature in this predominant application area. The existing studies measured the effectiveness of these academic web sites by taking into account their information architecture mostly using think-aloud methodology. However, there is limited study on web analytics tools which are capable of providing valuable information regarding the web site users such as their navigation behaviours and browser details. Although web analytics tools provide detailed and valuable information, the existing studies have utilized their very basic features. In this thesis, we have explored web analytic tools and think-aloud study method to improve information architecture of web sites. Taking METU Informatics Institute web site as a case study, we have used the reports of Google Analytics which is a commercial web analytics tool owned by Google and think-aloud study results to improve the information architecture of our case study web-site.

Dans le cadre de trois projets européens, notre équipe a mis au point un modèle de données et un langage de requête pour bibliothèques numériques supportant l'identification, la structuration, les métadonnées, la réutilisation, et la découverte des ressources numériques. Le modèle proposé est inspiré par le Web et il est formalisé comme une théorie du premier ordre, dont certains modèles correspondent à la notion de bibliothèque numérique. En outre, une traduction complète du modèle en RDF et du langage de requêtes en SPARQL a également été proposée pour démontrer son adéquation à des applications pratiques. Le choix de RDF est dû au fait qu'il est un langage de représentation généralement accepté dans le cadre des bibliothèques numériques et du Web sémantique. L'objectif de cette thèse était double: concevoir et mettre en œuvre une forme simplifiée de système de gestion de bibliothèques numériques, d'une part, et contribuer à l'enrichissement du modèle, d'autre part. Pour atteindre cet objectif nous avons développé un prototype d'un système de bibliothèque numérique utilisant un stockage RDF pour faciliter la gestion interne des métadonnées. Le prototype permet aux utilisateurs de gérer et d'interroger les métadonnées des ressources numériques ou non-numériques dans le système en utilisant des URIs pour identifier les ressources, un ensemble de prédicats pour la description de ressources, et des requêtes conjonctives simples pour la découverte de connaissances dans le système. Le prototype est mis en œuvre en utilisant les technologies Java et l'environnement de Google Web Toolkit dont l'architecture du système se compose d'une couche de stockage, d'une couche de métier logique, d'une couche de service, et d'une interface utilisateur. Pendant la thèse, le prototype a été construit, testé et débogué localement, puis déployé sur Google App Engine. Dans l'avenir, il peut être étendu pour devenir un système complet de gestion de bibliothèques numériques. Par ailleurs, la thèse présente également notre contribution à la génération de contenu par réutilisation de ressources. Il s'agit d'un travail théorique dont le but est d'enrichir le modèle en lui ajoutant un service important, à savoir la possibilité de création de nouvelles ressources à partir de celles stockées dans le système. L'incorporation de ce service dans le système sera effectuée ultérieurement.

This document is especially aimed at web services technologies and testing them using fault injection methods. The work deals with Service-Oriented Architecture, used as a standard for web service implementation, and with software testing in general. Practical part of the project includes the design and realization of a tool, which is able to test the most common types of web services according to setup criteria. To demonstrate its functionality, some of the sample and public web services were tested.