A Linear Logic approach to RESTful web service modelling and composition

A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of PhilosophyRESTful Web Services are gaining increasing attention from both the service and the Web communities. The rising number of services being implemented and made available on the Web is creating a demand for modelling techniques that can abstract REST design from the implementation in order better to specify, analyse and implement large-scale RESTful Web systems. It can also help by providing suitable RESTful Web Service composition methods which can reduce costs by effi ciently re-using the large number of services that are already available and by exploiting existing services for complex business purposes. This research considers RESTful Web Services as state transition systems and proposes a novel Linear Logic based approach, the first of its kind, for both the modelling and the composition of RESTful Web Services. The thesis demonstrates the capabilities of resource-sensitive Linear Logic for modelling five key REST constraints and proposes a two-stage approach to service composition involving Linear Logic theorem proving and proof-as-process based on the π-calculus. Whereas previous approaches have focused on each aspect of the composition of RESTful Web Services individually (e.g. execution or high-level modelling), this work bridges the gap between abstract formal modelling and application-level execution in an efficient and effective way. The approach not only ensures the completeness and correctness of the resulting composed services but also produces their process models naturally, providing the possibility to translate them into executable business languages. Furthermore, the research encodes the proposed modelling and composition method into the Coq proof assistant, which enables both the Linear Logic theorem proving and the π-calculus extraction to be conducted semi-automatically. The feasibility and versatility studies performed in two disparate user scenarios (shopping and biomedical service composition) show that the proposed method provides a good level of scalability when the numbers of services and resources grow

WSMO-Lite and hRESTS: lightweight semantic annotations for Web services and RESTful APIs

Service-oriented computing has brought special attention to service description, especially in connection with semantic technologies. The expected proliferation of publicly accessible services can benefit greatly from tool support and automation, both of which are the focus of Semantic Web Service (SWS) frameworks that especially address service discovery, composition and execution. As the first SWS standard, in 2007 the World Wide Web Consortium produced a lightweight bottom-up specification called SAWSDL for adding semantic annotations to WSDL service descriptions. Building on SAWSDL, this article presents WSMO-Lite, a lightweight ontology of Web service semantics that distinguishes four semantic aspects of services: function, behavior, information model, and nonfunctional properties, which together form a basis for semantic automation. With the WSMO-Lite ontology, SAWSDL descriptions enable semantic automation beyond simple input/output matchmaking that is supported by SAWSDL itself. Further, to broaden the reach of WSMO-Lite and SAWSDL tools to the increasingly common RESTful services, the article adds hRESTS and MicroWSMO, two HTML microformats that mirror WSDL and SAWSDL in the documentation of RESTful services, enabling combining RESTful services with WSDL-based ones in a single semantic framework. To demonstrate the feasibility and versatility of this approach, the article presents common algorithms for Web service discovery and composition adapted to WSMO-Lite

RESTful Service Composition

The Service-Oriented Architecture (SOA) has become one of the most popular approaches to building large-scale network applications. The web service technologies are de facto the default implementation for SOA. Simple Object Access Protocol (SOAP) is the key and fundamental technology of web services. Service composition is a way to deliver complex services based on existing partner services. Service orchestration with the support of Web Services Business Process Execution Language (WSBPEL) is the dominant approach of web service composition. WSBPEL-based service orchestration inherited the issue of interoperability from SOAP, and it was furthermore challenged for performance, scalability, reliability and modifiability. I present an architectural approach for service composition in this thesis to address these challenges. An architectural solution is so generic that it can be applied to a large spectrum of problems. I name the architectural style RESTful Service Composition (RSC), because many of its elements and constraints are derived from Representational State Transfer (REST). REST is an architectural style developed to describe the architectural style of the Web. The Web has demonstrated outstanding interoperability, performance, scalability, reliability and modifiability. RSC is designed for service composition on the Internet. The RSC style is composed on specific element types, including RESTful service composition client, RESTful partner proxy, composite resource, resource client, functional computation and relaying service. A service composition is partitioned into stages; each stage is represented as a computation that has a uniform identifier and a set of uniform access methods; and the transitions between stages are driven by computational batons. RSC is supplemented by a programming model that emphasizes on-demand function, map-reduce and continuation passing. An RSC-style composition does not depend on either a central conductor service or a common choreography specification, which makes it different from service orchestration or service choreography. Four scenarios are used to evaluate the performance, scalability, reliability and modifiability improvement of the RSC approach compared to orchestration. An RSC-style solution and an orchestration solution are compared side by side in every scenario. The first scenario evaluates the performance improvement of the X-Ray Diffraction (XRD) application in ScienceStudio; the second scenario evaluates the scalability improvement of the Process Variable (PV) snapshot application; the third scenario evaluates the reliability improvement of a notification application by simulation; and the fourth scenario evaluates the modifiability improvement of the XRD application in order to fulfil emerging requirements. The results show that the RSC approach outperforms the orchestration approach in every aspect

Desenvolvimento de uma Infraestrutura baseada em HL7® FHIR® para Interoperabilidade Clínica

Throughout the years, the healthcare business knowledge, requirements, and the number of patients seeking medical attention has grown tremendously to a point where sensitive cases needed the input from multiple healthcare institutions in order to track the patient’s medical history and make the most adequate decisions for each situation. Technology and digital information fulfils a great role in addressing these problems and improving healthcare provision. However, due to the immense number of organizations and systems in this business, sharing a patient’s clinical information can be a major problem if the systems are not capable of understanding the data sent to each other. Ensuring interoperability between systems is crucial to guarantee the continuous flow of a patient’s clinical history transmission and to improve the health professionals’ work. As a company working in the field of healthcare, ALERT’s main goal is to help organizations improve in their health business and to help prolong life, by providing the necessary technology that is capable of benefiting the health professional’s work management and sharing the necessary information with other organizations. Thus, the company seeks to constantly improve its product suite, ALERT®, by meeting the worldwide organizations requirements and assuring interoperability based on the existing health standards in the market. This way, the company wants to add in the ALERT suite the latest standard, Fast Healthcare Interoperability Resources (FHIR ® ), which brings great technological innovations for interoperability’s improvement, provided by the standards developing organization, Health Level Seven International (HL7), being also considered to be a suitable standard for mobile applications thanks to its capabilities and ease of implementation. Herewith, thisthesis presents a development and architectural approach to apply FHIR features in the product suite, along with the problem and solution analysis, including the evaluation of suitable frameworks for the implementation phase. Considering the experiments’ results, the implemented FHIR services actually improved the product’s performance, and thanks to the standard’s specification, the implementation of its core features proved to be simple and straightforward while respecting the key criteria for some of the developed services.Ao longo dos anos, o conhecimento, as exigências, e o número de pacientes à procura de cuidados médicos na área de negócio de cuidados de saúde, tem vindo a aumentar drasticamente ao ponto de ser necessária a opinião de outras instituições para casos de maior sensibilidade, de modo a que o historial médico do paciente fosse acompanhado e que servisse para tomar as decisões mais adequadas para o problema em questão. A tecnologia e a informação digital representam um grande papel na resolução de problemas e promoção de entrega de cuidados de saúde. No entanto, devido à imensa quantidade de organizações e sistemas nesta área de negócio, a partilha de informação clínica relativa a um paciente pode vir a ser um grave problema caso os sistemas não sejam capazes de compreender os dados que estão a ser transmitidos entre eles. Deste modo, assegurar interoperabilidade entre sistemas é crucial para garantir um fluxo contínuo de transmissão de informação relativa ao historial clínico de um paciente, e para melhorar o trabalho dos profissionais de saúde. Sendo uma empresa que trabalha na área de cuidados de saúde, a ALERT tem como principal objetivo ajudar as organizações a melhorar o seu negócio de saúde e ajudar a prolongar a vida, fornecendo a tecnologia necessária que beneficie a gestão de trabalho dos profissionais de saúde e que partilhe informação com outras organizações. Portanto, a empresa procura constantemente melhorar o seu produto ALERT®, procurando cumprir com os requisitos de organizações globais e garantindo interoperabilidade baseada nos standards de saúde existentes no mercado. Assim, a empresa pretende adotar o último standard lançado, Fast Healthcare Interoperability Resources (FHIR®), que traz grandes inovações tecnológicas para o aperfeiçoamento da interoperabilidade, fornecida pela organização de desenvolvimento de standards, Health Level Seven International (HL7), sendo também considerado um standard adequado para aplicações móveis graças às suas capacidades e facilidade de implementação. Com isto, esta tese apresenta uma abordagem arquitetural e de desenvolvimento para a aplicação de funcionalidades FHIR no produto, juntamente com a análise do problema e da solução, incluindo a avaliação de ferramentas adequadas para a fase de implementação. Os resultados de teste obtidos para os serviços FHIR implementados, demonstraram uma melhoria na performance do produto, e graças à especificação do standard, a implementação das principais funcionalidades provou ser simples e direta, respeitando os principais critérios para os serviços desenvolvidos