Web Service Description Research Articles

Study on Custom Service Combination Based on BPEL

A custom service combination based on Business Process Execution Language was put forward. It mainly studied one-off recipient and keeping the business logic order unchanged. It was proposed a solution that made the serial workflow realize the local parallelism from three aspects such as message dependency, a directed acyclic graph to workflow, and the implicit message dependency. The algorithm of implementation was also discussed. A custom service combination application of ‘stocking house transactions’ and ‘stocking house mortgage’ showed the feasibility and validity of this algorithm. The system generates the BPEL by analyzing various business stakeholders’ Web Service Description Language interface thereby determining the dependence of each business order, together with maintaining the existing business logic. The BPEL enhances the local parallel processing, and makes the overall processing time reduced.

Service-oriented architecture (SOA) concepts and implementations

This tutorial explains how to implement a Service-Oriented Architecture (SOA) for reliable systems using an Enterprise Service Bus (ESB) and the Ada Web Server (AWS). The first part of the tutorial describes terms of Service-Oriented Architectures (SOA) including service, service registry, service provider, service consumer, Service Oriented Architecture Protocol (SOAP), and Web Service Description Language (WSDL). This tutorial also presents principles of SOA including loose coupling, encapsulation, composability of web services, and statelessness of web services. The tutorial also covers the benefits of SOA and organizations that are supporting SOA infrastructure. The second part of the tutorial covers the Enterprise Service Bus (ESB) including definitions, capabilities, benefits and drawbacks. The tutorial discusses the difference between SOA and an ESB, as well as some of the commercially available ESB solutions on the market. The Mule ESB is explored in more detail and several examples are given. In the third part, the tutorial covers the Ada Web Server (AWS) built using the Ada programming language. The tutorial covers the capabilities of AWS and explains how to build and install AWS. The tutorial explains how to build an AWS server and include the server in an Ada application. The tutorial demonstrates how to build a call back function in AWS and build a response to a SOAP message. Finally, the tutorial explains how to connect an AWS server to an ESB endpoint. AWS is a key component to building a SOA for a reliable system. This capability allows the developer to expose services in a high-integrity system using the Ada and SPARK programming languages.

Knowledge-based personalized search engine for the Web-based Human Musculoskeletal System Resources (HMSR) in biomechanics

Human musculoskeletal system resources of the human body are valuable for the learning and medical purposes. Internet-based information from conventional search engines such as Google or Yahoo cannot response to the need of useful, accurate, reliable and good-quality human musculoskeletal resources related to medical processes, pathological knowledge and practical expertise. In this present work, an advanced knowledge-based personalized search engine was developed. Our search engine was based on a client–server multi-layer multi-agent architecture and the principle of semantic web services to acquire dynamically accurate and reliable HMSR information by a semantic processing and visualization approach. A security-enhanced mechanism was applied to protect the medical information. A multi-agent crawler was implemented to develop a content-based database of HMSR information. A new semantic-based PageRank score with related mathematical formulas were also defined and implemented. As the results, semantic web service descriptions were presented in OWL, WSDL and OWL-S formats. Operational scenarios with related web-based interfaces for personal computers and mobile devices were presented and analyzed. Functional comparison between our knowledge-based search engine, a conventional search engine and a semantic search engine showed the originality and the robustness of our knowledge-based personalized search engine. In fact, our knowledge-based personalized search engine allows different users such as orthopedic patient and experts or healthcare system managers or medical students to access remotely into useful, accurate, reliable and good-quality HMSR information for their learning and medical purposes.

Complete and reusable description of message structural constraints in web service interfaces

Existing specifications for describing message structure as a part of web service description do not support use case-specific definition of structural constraints. We propose a solution to describe a complete set of structural constraints for a particular business object in all its use cases. To implement our solution we use XML Schema (XSD), de facto standard for description of web service message structure. We propose XSD extensions that realize two distinct and complementary approaches. Measurements have shown that by using our extensions the average complexity of real world schemas (XSD documents) comparing to expressional equivalent alternatives is smaller by ~29%.

Service substitutability analysis based on behavior automata

Identifying a suitable service to substitute the failed service in Web service composition is a primary means to improve the robustness and dependability of service-oriented computing and cloud computing. Service behavioral substitutability analysis and verification is the main research subject of service-oriented computing. In this paper, based on Finite Automata and characteristics of service-oriented software systems, service behavior automata have been proposed to describe Web service behavior protocols formally; a conceptual hierarchy of service behavioral substitutability has been formally defined to increase service component reuse, and related verification algorithms have been proposed to analyze service behavioral substitutability automatically.

WSDATool: A Novel Web Service Developer Assistance Tool Using a New Complementary Service Publishing Method

Web service technology (WST) is a service-oriented architecture implementation framework that makes designing component-based internet applications possible. At present, many providers offer their services as web services. Current WST suffers from the lack of an integrated tool to assist web service developers. In WST, the services are published publicly, and their descriptions are stored in service directories. These descriptions contain valuable information about the work of different software teams throughout the world. However, with the increasing number of web services, searching for services is difficult and time-consuming. Furthermore, in current service directories, there is a little knowledge about the services, and extraction of useful information to be utilised by developers is not easy. In this paper, in order to increase the knowledge of what is available in service directories, a structure is presented by interlinking WST entities by using some defined semantic relations. The proposed structure provides a framework and a tool named WSDATool to develop new web services using information from published services or to refine current published web service descriptions. In experiments, services designed with the assistance of the WSDATool are more coherent and well designed.

Fault‐tolerant timestamp‐based two‐phase commit protocol for RESTful services

SUMMARYService‐oriented architecture provides interoperability and weak coupling features for software development. Representational state transfer (REST) is an architectural style that has attracted attention in the SOA domain as it allows the development of Web services based on original principles of the World Wide Web. Unlike Web service specifications, which are based on Simple Object Access Protocol and Web Services Description Language, REST does not provide ‘official’ standards to address non‐functional requirements of services, such as security, reliability, and transaction control. The timestamp‐based two‐phase commit protocol for RESTful service (TS2PC4RS) algorithm specifies concurrency control of RESTful services during a transaction. An extension of the TS2PC4RS specifies the concurrency control of the Web services considering the update operation to meet some business rules. However, neither algorithm addresses transaction control when failures occur. In long‐term transactions, failures can occur and compromise the success of Web service applications. Two common failures traditionally considered in the analysis of protocols are host and connection failures. The aim of this paper is to address fault tolerance for TS2PC4RS and its extension. A fault‐tolerant protocol based on timeout and log records is proposed. The fault‐tolerant protocol provides support for the host and connection failures that may occur during a transaction execution. The fault‐tolerant mechanisms are used to meet the application domain business rules that guide the behavior of RESTful services. We describe the protocol using scenarios when failures occur. Copyright © 2012 John Wiley & Sons, Ltd.

UncertWeb Processing Service: Making Models Easier to Access on the Web

AbstractModels are central tools for modern scientists and decision makers, and there are many existing frameworks to support their creation, execution and composition. Many frameworks are based on proprietary interfaces, and do not lend themselves to the integration of models from diverse disciplines. Web‐based systems, or systems based on web services, such as Taverna and Kepler, allow the composition of models based on standard web service technologies. At the same time the Open Geospatial Consortium has been developing their own service stack, which includes the Web Processing Service, designed to facilitate execution of geospatial processing – including complex environmental models. The current Open Geospatial Consortium service stack employs Extensible Markup Language as a default data exchange standard, and widely‐used encodings such as JavaScript Object Notation can often only be used when incorporated with Extensible Markup Language. Similarly, no successful engagement has been seen of the Web Processing Service standard with the well‐supported technologies of Simple Object Access Protocol and Web Services Description Language. In this article we propose a pure Simple Object Access Protocol/Web Services Description Language processing service, which addresses some of the issues with the Web Processing Service specification and brings us closer to achieving a degree of interoperability between geospatial models, thus realizing the vision of a useful ‘model web’.

Structured Communication-Centered Programming for Web Services

This article relates two different paradigms of descriptions of communication behavior, one focusing on global message flows and another on end-point behaviors, using formal calculi based on session types. The global calculus, which originates from a Web service description language (W3C WS-CDL), describes an interaction scenario from a vantage viewpoint; the end-point calculus, an applied typed π -calculus, precisely identifies a local behavior of each participant. We explore a theory of end-point projection, by which we can map a global description to its end-point counterparts preserving types and dynamics. Three principles of well-structured description and the type structures play a fundamental role in the theory.

A Policy-Based Web Service Redundancy Detection in Wireless Sensor Networks

Wireless sensor networks (WSNs) are attractive for monitoring and gathering physical information (e.g. temperature) via lots of deployed sensors. For the applications in WSNs, Web service is one of the recommended frameworks to publish, invoke, and manage services. However, the standard Web service description language (WSDL), defines only the service input and output while ignoring the corresponding input-to-output mapping relationships. This presents a serious challenge in distinguishing services with similar input and output interface. In this paper, we address this challenge by embedding the service policy into the traditional WSDL2.0 schema to describe the input-to-output mapping relationships. The service policy is then transformed into a policy binary tree so that the similarity between different Web services can be quantitatively evaluated. Furthermore, a new service redundancy detection approach is proposed based on this similarity. Finally, the case study and experimental analysis illustrate the applicability and capability of the proposed service redundancy detection approach.

A Semantically Automated Protocol Adapter for Mapping SOAP Web Services to RESTful HTTP Format to Enable the Web Infrastructure, Enhance Web Service Interoperability and Ease Web Service Migration

Semantic Web Services (SWS) are Web Service (WS) descriptions augmented with semantic information. SWS enable intelligent reasoning and automation in areas such as service discovery, composition, mediation, ranking and invocation. This paper applies SWS to a previous protocol adapter which, operating within clearly defined constraints, maps SOAP Web Services to RESTful HTTP format. However, in the previous adapter, the configuration element is manual and the latency implications are locally based. This paper applies SWS technologies to automate the configuration element and the latency tests are conducted in a more realistic Internet based setting.

Best practices for describing, consuming, and discovering web services: a comprehensive toolset

SUMMARYThe service‐oriented computing (SOC) paradigm has recently gained a lot of attention in the software industry because SOC represents a novel and a fresh way of architecting distributed applications. SOC is usually materialized via web services, which allows developers to structure applications exposing a clear, public interface to their capabilities. Although conceptually and technologically mature, SOC still lacks adequate development support from a methodological point of view. In this paper, we present the EasySOC project, a set of guidelines to simplify the development of service‐oriented applications and services. EasySOC is a synthesized catalog of best SOC development practices that arise as a result of several years of research in fundamental Services Computing topics, that is, Web Service Description Language‐based technical specification, Web Service discovery, and Web Service outsourcing. In addition, we describe a materialization of the guidelines for the Java language, which has been implemented as a plug‐in for the Eclipse IDE. We believe that both the practical nature of the guidelines and the availability of this software that enforces them may help software practitioners to rapidly exploit our ideas for building real SOC applications. Copyright © 2012 John Wiley & Sons, Ltd.

The WTE+ framework: automated construction and runtime adaptation of service mashups

An emerging software engineering methodology is the combination of functionality and content from existing software components into service mashups, creating greater value than the sum of the individual participating building blocks. For businesses, using catalogues of reusable services means agile development of new applications using open communication standards including the Simple Object Access Protocol (SOAP) for transmitting data, and the Web Services Description Language (WSDL) for defining services. The result is faster adaptation to the changing business environment creating value at reduced development time and cost while increasing revenues. This manuscript presents the developed service management framework and evaluation results of the WTE+ (Web2.0/Telco2.0/Enterprise2.0 with semantics) research project. Main goal is supporting application developers with the automatic construction and runtime reconfiguration of custom-made service mashups at a minimum performance cost without the need for constant IT intervention. Semantically enriched services are automatically combined into custom-made service mashups by the designed planning algorithms. These planning techniques are optimized with late binding and runtime adaptation to changing user-context taking fully into account the quality of service parameters of the available components which are provided at design time and updated at runtime. In addition, recovery mechanisms are provided in case of failed services and/or resources. During mashup execution, unavailable services are dynamically replaced by equivalent ones or alternative service mashups keeping in mind the current execution state. The developed planning algorithms are put through extensive performance and scalability experiments for a typical e-commerce scenario, in which e-shop services such as product payment and delivery are on-the-fly composed to an e-shop application. The results show that an automatic construction of a new application out of existing services can take up between 5 to 43 seconds for 500 services while runtime adaptation takes up to 5 seconds on average depending on the availability of equivalent services.

Capturing the functionality of Web services with functional descriptions

Many have left their footprints on the field of semantic RESTful Web service description. Albeit some of the propositions are even W3C Recommendations, none of the proposed standards could gain significant adoption with Web service providers. Some approaches were supposedly too complex and verbose, others were considered not RESTful, and some failed to reach a significant majority of API providers for a combination of the reasons above. While we neither have the silver bullet for universal Web service description, with this paper, we want to suggest a lightweight approach called RESTdesc. It expresses the semantics of Web services by pre- and postconditions in simple N3 rules, and integrates existing standards and conventions such as Link headers, HTTP OPTIONS, and URI templates for discovery and interaction. This approach keeps the complexity to a minimum, yet still enables service descriptions with full semantic expressiveness. A sample implementation on the topic of multimedia Web services verifies the effectiveness of our approach.

A recommender system based on historical usage data for web service discovery

The tremendous growth in the amount of available web services impulses many researchers on proposing recommender systems to help users discover services. Most of the proposed solutions analyzed query strings and web service descriptions to generate recommendations. However, these text-based recommendation approaches depend mainly on user's perspective, languages, and notations, which easily decrease recommendation's efficiency. In this paper, we present an approach in which we take into account historical usage data instead of the text-based analysis. We apply collaborative filtering technique on user's interactions. We propose and implement four algorithms to validate our approach. We also provide evaluation methods based on the precision and recall in order to assert the efficiency of our algorithms.

Effective web service description and dynamic discovery mechanism based on the functional semantics

The service-oriented architecture (SOA) has become a popular architecture for modern distributed systems. Web services form one of the central technologies to realise service-oriented architecture. The ability to discover, select and compose inter-organisational and heterogeneous services available on the web at runtime to facilitate application reuse is an interesting problem in web services. The efficient and effective mechanism for discovery, selection and composition of web services, based on the requester’s complex functional and non-functional requirements is still an issue of open research. The research work described in this paper, mainly aims at discovery mechanism for web services. To realise the dynamic lookup mechanism, the broker-based architecture is defined for web services which is a crux of the web service discovery mechanism. This paper defines functional semantics which describe web service operation functionality in a natural form using action and object(s). A tree structure is proposed for quick discovery which is a compact representation of advertised web services (service registry) and their operations. The use of functional semantics and a tree structure representation of web services improve the effectiveness of the web service description and discovery mechanism.

Injecting Semantic Annotations into (Geospatial) Web service descriptions

Geospatial Web services comply with well-established standards to support seamless integration into applications ranging from commercial Geographic Information Systems GIS to open source web mapping clients. Descriptions of service capabilities contain information about the provided data. Updates to the underlying database result in changing descriptions. To ensure compatibility with existing solutions, semantic enablement of Geospatial Web services has to reflect both, standards and changing metadata. Semantic annotations link between legacy non-semantic Web service descriptions and their semantic counterparts. The open source Semantic Annotations Proxy SAPR is a light-weight RESTful API deployed as free service which “injects” semantic annotations into existing Web service descriptions without breaking the standards. This approach decouples the annotations from the original metadata, which ensures the separation of concerns between data providers and end users with different and sometimes conflicting views on annotations. In addition, the service is robust regarding changes of the service descriptions. The presented approach is focusing on W3C-and OGC-compliant Web services, but can be theoretically applied on any kind of information source with structured metadata.

S-Match: An open source framework for matching lightweight ontologies

Achieving automatic interoperability among systems with diverse data structures and languages expressing different viewpoints is a goal that has been difficult to accomplish. This paper describes S-Match, an open source semantic matching framework that tackles the semantic interoperability problem by transforming several data structures such as business catalogs, web directories, conceptual models and web services descriptions into lightweight ontologies and establishing semantic correspondences between them. The framework is the first open source semantic matching project that includes three different algorithms tailored for specific domains and provides an extensible API for developing new algorithms, including possibility to plug-in specific background knowledge according to the characteristics of each application domain.

AWS-Policy: An Extension for Autonomic Web Service Description

In the last years, the need for integrating QoS to service oriented architecture has become a significant factor for managing service-based systems. In addition, combining self-* and policy-based management has major advantages since it reduces complexity management and effectively drives self-adaptation of Web services. Current service oriented architecture does not support policy-based self-management. To allow this, the description of autonomic Web services (AWS) must not be limited to functional and non-functional data. Indeed, QoS data are not sufficient to effectively drive the self-adaptation process. In addition, providers must participate in the self-adaptation process as they are aware of the capabilities and requirements of their published services and the exceptions that may occur. In this paper, we propose a rich information model that allows describing autonomic Web services based not only on QoS data but also on additional information such as service specific adaptation actions. We extend WS-Policy to specify services related data. UDDI is also extended to support policy-based self-management.

An Integrated Approach to Automated Semantic Web Service Composition through Planning

The paper presents an integrated approach for automated semantic web service composition using AI planning techniques. An important advantage of this approach is that the composition process, as well as the discovery of the atomic services that take part in the composition, are significantly facilitated by the incorporation of semantic information. OWL-S web service descriptions are transformed into a planning problem described in a standardized fashion using PDDL, while semantic information is used for the enhancement of the composition process as well as for approximating the optimal composite service when exact solutions are not found. Solving, visualization, manipulation, and evaluation of the produced composite services are accomplished, while, unlike other systems, independence from specific planners is maintained. Implementation was performed through the development and integration of two software systems, namely PORSCE II and VLEPPO. PORSCE II is responsible for the transformation process, semantic enhancement, and management of the results. VLEPPO is a general-purpose planning system used to automatically acquire solutions for the problem by invoking external planners. A case study is also presented to demonstrate the functionality, performance, and potential of the approach.