A Dynamic Composition and Stubless Invocation Approach for Information-Providing Services

The automated specification and execution of composite services are important capabilities of service-oriented systems. In practice, service invocation is performed by client components (stubs) that are generated from service descriptions at design time. Several researchers have proposed mechanisms for late binding. They all require an object representation (e.g., Java classes) of the XML data types specified in service descriptions to be generated and meaningfully integrated in the client code at design time. However, the potential of dynamic composition can only be fully exploited if supported in the invocation phase by the capability of dynamically binding to services with previously unknown interfaces. In this work, we address this limitation by proposing a way of specifying and executing composite services, without resorting to previously compiled classes that represent XML data types. Semantic and structural properties encoded in service descriptions are exploited to implement a mechanism, based on the Graphplan algorithm, for the run-time specification of composite service plans. Composite services are then executed through the stubless invocation of constituent services. Stubless invocation is achieved by exploiting structural properties of service descriptions for the run-time generation of messages

Enhancement of the usability of SOA services for novice users

Recently, the automation of service integration has provided a significant advantage in delivering services to novice users. This art of integrating various services is known as Service Composition and its main purpose is to simplify the development process for web applications and facilitates reuse of services. It is one of the paradigms that enables services to end-users (i.e.service provisioning) through the outsourcing of web contents and it requires users to share and reuse services in more collaborative ways. Most service composers are effective at enabling integration of web contents, but they do not enable universal access across different groups of users. This is because, the currently existing content aggregators require complex interactions in order to create web applications (e.g., Web Service Business Process Execution Language (WS-BPEL)) as a result not all users are able to use such web tools. This trend demands changes in the web tools that end-users use to gain and share information, hence this research uses Mashups as a service composition technique to allow novice users to integrate publicly available Service Oriented Architecture (SOA) services, where there is a minimal active web application development. Mashups being the platforms that integrate disparate web Application Programming Interfaces (APIs) to create user defined web applications; presents a great opportunity for service provisioning. However, their usability for novice users remains invalidated since Mashup tools are not easy to use they require basic programming skills which makes the process of designing and creating Mashups difficult. This is because Mashup tools access heterogeneous web contents using public web APIs and the process of integrating them become complex since web APIs are tailored by different vendors. Moreover, the design of Mashup editors is unnecessary complex; as a result, users do not know where to start when creating Mashups. This research address the gap between Mashup tools and usability by the designing and implementing a semantically enriched Mashup tool to discover, annotate and compose APIs to improve the utilization of SOA services by novice users. The researchers conducted an analysis of the already existing Mashup tools to identify challenges and weaknesses experienced by novice Mashup users. The findings from the requirement analysis formulated the system usability requirements that informed the design and implementation of the proposed Mashup tool. The proposed architecture addressed three layers: composition, annotation and discovery. The researchers developed a simple Mashup tool referred to as soa-Services Provisioner (SerPro) that allowed novice users to create web application flexibly. Its usability and effectiveness was validated. The proposed Mashup tool enhanced the usability of SOA services, since data analysis and results showed that it was usable to novice users by scoring a System Usability Scale (SUS) score of 72.08. Furthermore, this research discusses the research limitations and future work for further improvements

Plataforma de serviços para monitorização da cadeia de valor do pescado

Traceability in the food value chain is a topic of interest due to the advantages it brings to both the consumers, producers and regulatory authorities. This thesis describes my contributions during the design and implementation of a microservice based middleware for the Portuguese fish value chain considering current practices in the industry and the requirements of the stakeholders involved in the project, with the goal of integrating all the traceability information available from each operator to provide customers with the full story of the products they purchase. During this project I assumed many roles such as development, operations and even some security allowing me to improve my skills in all these fields and experimenting with the latest cloud native technologies such as containers and with DevOps practices.A rastreabilidade na cadeia de valor alimentar é um tema de interesse pelas vantagens que traz aos consumidores, produtores e autoridades reguladoras. Esta dissertação descreve as minhas contribuições durante a conceção e implementação de um middleware baseado em micro-serviços para a cadeia de valor do pescado portuguesa considerando as práticas atuais da indústria e os requisitos das partes interessadas envolvidas no projeto, com o objetivo de integrar toda a informação de rastreabilidade disponível de cada um dos operadores para fornecer aos clientes a história completa dos produtos que adquirem. Durante este projeto, assumi muitas funções, como desenvolvimento, operações e até mesmo alguma segurança, o que me permitiu melhorar as minhas capacidades em todos essas disciplinas e experimentar as mais recentes tecnologias nativas da nuvem, como contentores e práticas de DevOps.Mestrado em Engenharia Informátic

A RESTful Rule Management Framework for Internet of Things Applications

Web technologies are currently regarded as key enabling factors for the Internet of Things (IoT), and substantial effort is being dedicated to bringing sensors and data from the real world to the Web. In addition, rule-based automation mechanisms are expected to play a significant role in the effective integration of the physical world with the virtual world by leveraging a trigger-action paradigm. Although several rule engines are already available, limited effort has been devoted to rule-based solutions that are tailored to the IoT and consider rule configurability and extensibility according to application requirements. In this work, we propose a RESTful rule management framework for IoT applications that satisfies these requirements. The framework is centered around a resource-based graph, which enables the uniform representation of things (e.g., sensors and domain entities) and rules as URI-addressable resources. We describe the design and implementation choices of the main rule management features (rule scheduling, activation and RESTful operations for managing rules at various levels of configurability and extensibility). Finally, we present a case study and performance evaluation results regarding the use of this rule management framework in a set of school buildings that were part of a real-world IoT deployment that was realized within the Horizon 2020 GAIA research project, with the objective of promoting energy -saving behaviors in school communities

Contribución a la estimulación del uso de soluciones Cloud Computing: Diseño de un intermediador de servicios Cloud para fomentar el uso de ecosistemas distribuidos digitales confiables, interoperables y de acuerdo a la legalidad. Aplicación en entornos multi-cloud.

184 p.El objetivo del trabajo de investigación presentado en esta tesis es facilitar a los desarrolladores y operadores de aplicaciones desplegadas en múltiples Nubes el descubrimiento y la gestión de los diferentes servicios de Computación, soportando su reutilización y combinación, para generar una red de servicios interoperables, que cumplen con las leyes y cuyos acuerdos de nivel de servicio pueden ser evaluados de manera continua. Una de las contribuciones de esta tesis es el diseño y desarrollo de un bróker de servicios de Computación llamado ACSmI (Advanced Cloud Services meta-Intermediator). ACSmI permite evaluar el cumplimiento de los acuerdos de nivel de servicio incluyendo la legislación. ACSmI también proporciona una capa de abstracción intermedia para los servicios de Computación donde los desarrolladores pueden acceder fácilmente a un catálogo de servicios acreditados y compatibles con los requisitos no funcionales establecidos.Además, este trabajo de investigación propone la caracterización de las aplicaciones nativas multiNube y el concepto de "DevOps extendido" especialmente pensado para este tipo de aplicaciones. El concepto "DevOps extendido" pretende resolver algunos de los problemas actuales del diseño, desarrollo, implementación y adaptación de aplicaciones multiNube, proporcionando un enfoque DevOps novedoso y extendido para la adaptación de las prácticas actuales de DevOps al paradigma multiNube

A framework for SLA-centric service-based Utility Computing

Nicht angegebenService oriented Utility Computing paves the way towards realization of service markets, which promise metered services through negotiable Service Level Agreements (SLA). A market does not necessarily imply a simple buyer-seller relationship, rather it is the culmination point of a complex chain of stake-holders with a hierarchical integration of value along each link in the chain. In service value chains, services corresponding to different partners are aggregated in a producer-consumer manner resulting in hierarchical structures of added value. SLAs are contracts between service providers and service consumers, which ensure the expected Quality of Service (QoS) to different stakeholders at various levels in this hierarchy. \emph{This thesis addresses the challenge of realizing SLA-centric infrastructure to enable service markets for Utility Computing.} Service Level Agreements play a pivotal role throughout the life cycle of service aggregation. The activities of service selection and service negotiation followed by the hierarchical aggregation and validation of services in service value chain, require SLA as an enabling technology. \emph{This research aims at a SLA-centric framework where the requirement-driven selection of services, flexible SLA negotiation, hierarchical SLA aggregation and validation, and related issues such as privacy, trust and security have been formalized and the prototypes of the service selection model and the validation model have been implemented. } The formal model for User-driven service selection utilizes Branch and Bound and Heuristic algorithms for its implementation. The formal model is then extended for SLA negotiation of configurable services of varying granularity in order to tweak the interests of the service consumers and service providers. %and then formalizing the requirements of an enabling infrastructure for aggregation and validation of SLAs existing at multiple levels and spanning % along the corresponding service value chains. The possibility of service aggregation opens new business opportunities in the evolving landscape of IT-based Service Economy. A SLA as a unit of business relationships helps establish innovative topologies for business networks. One example is the composition of computational services to construct services of bigger granularity thus giving room to business models based on service aggregation, Composite Service Provision and Reselling. This research introduces and formalizes the notions of SLA Choreography and hierarchical SLA aggregation in connection with the underlying service choreography to realize SLA-centric service value chains and business networks. The SLA Choreography and aggregation poses new challenges regarding its description, management, maintenance, validation, trust, privacy and security. The aggregation and validation models for SLA Choreography introduce concepts such as: SLA Views to protect the privacy of stakeholders; a hybrid trust model to foster business among unknown partners; and a PKI security mechanism coupled with rule based validation system to enable distributed queries across heterogeneous boundaries. A distributed rule based hierarchical SLA validation system is designed to demonstrate the practical significance of these notions

Interrogating Datafication

What constitutes a data practice and how do contemporary digital media technologies reconfigure our understanding of practices in general? Autonomously acting media, distributed digital infrastructures, and sensor-based media environments challenge the conditions of accounting for data practices both theoretically and empirically. Which forms of cooperation are constituted in and by data practices? And how are human and nonhuman agencies distributed and interrelated in data-saturated environments? The volume collects theoretical, empirical, and historiographical contributions from a range of international scholars to shed light on the current shift from media to data practices

Interrogating Datafication: Towards a Praxeology of Data

What constitutes a data practice and how do contemporary digital media technologies reconfigure our understanding of practices in general? Autonomously acting media, distributed digital infrastructures, and sensor-based media environments challenge the conditions of accounting for data practices both theoretically and empirically. Which forms of cooperation are constituted in and by data practices? And how are human and nonhuman agencies distributed and interrelated in data-saturated environments? The volume collects theoretical, empirical, and historiographical contributions from a range of international scholars to shed light on the current shift from media to data practices

Gamification as a Service: Conceptualization of a Generic Enterprise Gamification Platform

Gamification is a novel method to improve engagement, motivation, or participation in non-game contexts using game mechanics. To a large extent, gamification is a psychological- and design-oriented discipline, i.e., a lot of effort has to be spent already in the design phase of a gamification project. Subsequently, the design is implemented in information systems such as portals or enterprise resource planning applications. These systems act as mediators to transport a gameful design to its users. However, the efforts for the subsequent development and integration process are often underestimated. In fact, most conceptual gamification designs are never implemented due to the high development costs that arise from building the gamification solution from scratch, imprecise design or technical requirements, and communication conflicts between different stakeholders in the project. This thesis addresses these problems by systematically defining the phases and stakeholders of the overall gamification process. Furthermore, the thesis rigorously defines the conceptual requirements of gamification based on a broad literature review. The identified conceptual requirements are mapped to a domain-specific language, called the Gamification Modeling Language. Moreover, this thesis analyzes 29 existing gamification solutions that aim to decrease the implementation efforts of gamification. However, using the different language elements, it is shown that none of the existing solutions suffices all requirements. Therefore, a generic and reusable platform as runtime environment for gamification is proposed which fulfills all presented functional and non-functional requirements. As another benefit, it is shown how the Gamification Modeling Language can be automatically compiled into code for the gamification runtime environment and, thus, further reduces development efforts. Based on the developed artifacts and five real gamified applications from industry, it is shown that the efforts for the implementation of the gamification can be significantly reduced from several months or weeks to a few days. Since the technology is designed as a reusable service, future projects benefit continuously with regards to time and efforts