Semantic annotations for WSDL and XML schema

Anotaciones semánticas para WSDL y esquema XML (SAWSDL) define cómo añadir anotaciones semánticas en varias partes de un documento WSDL como la estructura de los mensajes de entrada y de salida, interfaces y operaciones. Los atributos anexos están definidos en esta forma dentro de los marcos de extensibilidad de WSDL 2.0 [WSDL 2.0], WSDL 1.1 [WSDL 1.1] y XML Schema

From RESTful Services to RDF: Connecting the Web and the Semantic Web

RESTful services on the Web expose information through retrievable resource representations that represent self-describing descriptions of resources, and through the way how these resources are interlinked through the hyperlinks that can be found in those representations. This basic design of RESTful services means that for extracting the most useful information from a service, it is necessary to understand a service's representations, which means both the semantics in terms of describing a resource, and also its semantics in terms of describing its linkage with other resources. Based on the Resource Linking Language (ReLL), this paper describes a framework for how RESTful services can be described, and how these descriptions can then be used to harvest information from these services. Building on this framework, a layered model of RESTful service semantics allows to represent a service's information in RDF/OWL. Because REST is based on the linkage between resources, the same model can be used for aggregating and interlinking multiple services for extracting RDF data from sets of RESTful services

Comprehensive service semantics and light-weight Linked Services: towards an integrated approach

Semantics are used to mark up a wide variety of data-centric Web resources but, are not used in significant numbers to annotate online services — that is despite considerable research dedicated to Semantic Web Services (SWS). This is partially due to the complexity of comprehensive SWS models aiming at automation of service-oriented tasks such as discovery, composition, and execution. This has led to the emergence of a new approach dubbed Linked Services which is based on simplified service models that are easier to populate and interpret and accessible even to non-experts. However, such Minimal Service Models so far do not cover all execution-related aspects of service automation and merely aim at enabling more comprehensive service search and clustering. Thus, in this paper, we describe our approach of combining the strengths of both distinct approaches to modeling Semantic Web Services – “lightweight” Linked Services and “heavyweight” SWS automation – into a coherent SWS framework. In addition, an implementation of our approach based on existing SWS tools together with a proof-of-concept prototype used within the EU project NoTube is presented

Interface refactoring in performance-constrained web services

This paper presents the development of REF-WS an approach to enable a Web Service provider to reliably evolve their service through the application of refactoring transformations. REF-WS is intended to aid service providers, particularly in a reliability and performance constrained domain as it permits upgraded ’non-backwards compatible’ services to be deployed into a performance constrained network where existing consumers depend on an older version of the service interface. In order for this to be successful, the refactoring and message mediation needs to occur without affecting functional compatibility with the services’ consumers, and must operate within the performance overhead expected of the original service, introducing as little latency as possible. Furthermore, compared to a manually programmed solution, the presented approach enables the service developer to apply and parameterize refactorings with a level of confidence that they will not produce an invalid or ’corrupt’ transformation of messages. This is achieved through the use of preconditions for the defined refactorings

JSON Schemas with Semantic Annotations Supporting Data Translation

Funding Information: Funding: This research was partially funded by EU ECSEL Joint Undertaking (JU) under grant agreement n° 826452 (project Arrowhead Tools).As service-oriented architectures are a solution for large distributed systems, interoperabil-ity between these systems, which are often heterogeneous, can be a challenge due to the different syntax and semantics of the exchanged messages or even different data interchange formats. This paper addresses the data interchange format and data interoperability issues between XML-based and JSON-based systems. It proposes novel annotation mechanisms to add semantic annotations and complement date values to JSON Schemas, enabling an interoperability approach for JSON-based systems that, until now, was only possible for XML-based systems. A set of algorithms supporting the translation from JSON Schema to XML Schema, JSON to XML, and XML to JSON is also pro-posed. These algorithms were implemented in an existing prototype tool, which now supports these systems’ interoperability through semantic compatibility verification and the automatic generation of translators.publishersversionpublishe

Automated Runtime Testing of Web Services

Service-oriented computing (SOC) is a relatively new paradigm for developing software applications through the composition of software units called services. With services, software is no longer owned but offered remotely, within or across organisational borders. Currently, the dominant technology for implementing services is that of Web services. Since service requestors do not usually have access to the implementation source code, from their perspective, services are offered as black boxes. However, requestors need to verify first that provided services are trustworthy and implemented correctly before they are integrated into their own business-critical systems. The verification and testing of remote, third-party services involve unique considerations, since testing must be performed in a blackbox manner and at runtime. Addressing the aforementioned concerns, the research work described in this thesis investigates the feasibility of testing Web services for functional correctness, especially at runtime. The aim is to introduce rigour and automation to the testing process, so that service requestors can verify Web services with correctness guarantees and with the aid of tools. Thus, formal methods are utilised to specify the functionality of Web services unambiguously, so that they are amenable to automated and systematic testing. The well-studied stream X-machine (SXM) formalism has been selected as suitable for modelling both the dynamic behavior and static data of Web services, while a proven testing method associated with SXMs is used to derive test sets that can verify the correctness of the implementations. This research concentrates on testing stateful Web services, in which the presence of state makes their behaviour more complex and more difficult to specify and test. The nature of Web service state, its effect on service behaviour, and implications on service modelling and testing, are investigated. In addition, comprehensive techniques are described for deriving a stream X-machine specification of a Web service, and for subsequently testing its implementation for equivalence to the specification. Then, a collaborative approach that makes possible third-party Web service verification and validation is proposed, in which the service provider is required to supply a SXM specification of the service functionality along with the standard WSDL description of its interface. On top of that, techniques are proposed for service providers to include information that ground the abstract SXM specification to the concrete Web service implementation. Having these descriptions available, it is possible to automate at runtime not only test set generation but also test case execution on Web services. A tool has been developed as part of this work, which extends an existing SXM-based testing tool (JSXM). The tool supports the tester activities, consisting of generation of abstract test cases from the SXM specification and their execution on the Web service under test using the supplied grounding information. Practical Web service examples are also used throughout the thesis to demonstrate the proposed techniques

Semantic Model Annotation Tool

Model driven interoperability is a research field that has gotten a lot of attention and money. Several research projects over the past years such as ATHENA, SWING and MODELWARE have sought to bring solutions to this field. The latest efforts involve the use of formal semantic descriptions to ease the interoperability task. Recent technologies on a lower level, such as SAWSDL has also presented new opportunities in the field. This thesis proposes to elevate the annotation to the platform independent level (PIM), complying with the Model Driven Architecture (MDA) vision of the MDE paradigm. Doing the annotation at this level will enable us to specify mappings to and from the ontology. Further this will enable us to generate specific mappings between PIMs that are annotated by, and mapped to, the ontology. Benefits are many, especially in the fields of model integration, validation, constraint checking and the creation of a common vocabulary that the annotated models adhere to. The latter is especially an important property in a world that sees more distributed software development, where domain experts and developers often find themselves at the opposite sides of the world. This thesis puts a focus on the integration aspect and shows how a annotated model can be transformed to another representation using the annotations and its definitions of the lifting and lowering operations. The thesis aim is to show that these annotations are feasible and represents added value in the context of MDA software development. We propose, and construct, a specific tool to handle annotation, mapping and validation of models and ontologies. They are annotated through a metamodel that support relations between both. This tool is based on the Eclipse platform, and is extensible with regard to future transformation technologies. The proposal is evaluated in the context of a specific case that presents two domain models rooted in a buyer/seller context. These models are expressed as UML class diagrams. A reference ontology that is the equivalent of one of the UML models represents the common vocabulary that we want to connect the models to. We then evaluate the solution in the light of this and show that semantic annotation of models is possible and could provide assistance and concrete solutions to many problems that face developers

Methodology for Detection of Cloud Interoperability Problems

Interoperability problems between cloud providers are one of the most serious issues of this new computing paradigm. A methodology is needed to systematically and effectively find and solve interoperability problems. For these reasons, a new methodology with detailed steps to find and solve interoperability problems is proposed here. This new methodology is focused and implemented on the platform as a service model, but it can be used in any of the three main models of cloud computing. The methodology uses an iterative approach, because platform as a service offers and their application programming interfaces evolve and change very often. The focus of the methodology is to use remote cloud application programming interfaces to solve interoperability problems on technical, storage and services levels, respectively. Finally, we show the application of the methodology to achieve service-level interoperability among different providers of platform as a service