Web Service Description Language Research Articles

A modelling language and a tool for web services composition

Web services technology is the most common implementation of service oriented architecture. Web services are based on open technologies such as eXtensible Markup Language (XML) and offer a distributed approach for the integration of heterogeneous applications across the internet. The process of combining web services functionalities into one composite service is called web services composition. To perform this task, several languages such as Business Process Execution Language (BPEL), Web Services Flow Language (WSFL) and Web Service Choreography Interface (WSCI) have emerged. These languages are based on programming concepts and neglect the specification step which is very important in any software development process. In this paper, we address the formal specification of web services descriptions and the modelling of their composition using the model driven engineering principles. To this end, we propose a domain specific language (DSL) called S-GNet. The proposed DSL introduces new modelling elements which make it well adapted to the web services characteristics. We also propose a graph grammar which transforms Web Services Description Language (WSDL) descriptions into their equivalent S-GNet specifications. This grammar is integrated within an S-GNet modelling tool.

SELECTION OF ONTOLOGY FOR WEB SERVICE DESCRIPTION LANGUAGE TO ONTOLOGY WEB LANGUAGE CONVERSION

Semantic web is to extend the current human readable web to encoding some of the semantic of resources in a machine processing form. As a Semantic web component, Semantic Web Services (SWS) uses a mark-up that makes the data into detailed and sophi sticated machine readable way. One such language is Ontology Web Language (OWL). Existing conventional web service annotation can be changed to semantic web service by mapping Web Service Description Language (WSDL) with the semantic annotation of OWL-S. In this conversion of WSDL to OWL process, the ontology plays a vital role. Ontology can be stored and retrieved from local rep ository and selecting the appropriate ontology is a complicated process and this can be achieved by Ont ology Searching and Property Matching (OSPM) engine. Ontology is stored in the local repository as ontology document and exact matching of ontology for the requested query can be searched using seman tic similarity ranking method. High ranked classes of ontology will undergo property matching; here reque sted concept will be matched with the resulting property. OSPM engine act as the backbone for selec ting an exact ontology and reduce the conflict that occurs while selecting the ontology for annotation purpose.

A loan management system as web services: a case study on a microfinance institution

Despite the determination of small microfinance institutions to expand into rural areas, they are limited by geographical isolation and high transaction costs. To set those institutions and their customers free from geographical constraints, we suggest isolated populations access some features of the enterprise application via Smartphone. This solution is based on a service-oriented architecture in which the main features are developed as web services. The invocation of the methods is performed from a Smartphone or a personal computer PC, while the execution will be done on a server that returns an understandable result through web service description language WSDL generated by web services, where the transport is provided by simple object access protocol SOAP.

Ontology-Based Context Modelling and Reasoning in the Web Service Migration Framework

The advancement in ubiquitous computing requires more effort to cope with contextual changes in the environment and to adapt to these changes in regular and efficient ways. A context model and context-awareness are proposed to provide a model of the contextual information and to describe its impact on individual behaviour of system's components and on rules and relationships which control their interactions. This paper extends the Web service migration framework which provides software support for services migrating between potential service providers in service-oriented architecture according to the contextual changes. The extension utilises ontology-based context modelling in OWL/RDF and reasoning by means Jena reasoners and rules to make necessary migration decisions. Applications of ubiquitous computing in diverse envi- ronments and needs for automatic adaptation to cope with changing contextual information in the environments lead to emerging context awareness in the ubiquitous systems. The context awareness enables a system to process contextual in- formation, to be aware of contextual changes and consequent interactions between system components during runtime. Context-aware computing was introduced at the first time by (1) as the ability of a mobile user's applications to dis- cover and react to changes in the environment. The mobile user uses these applications to monitor and derive informa- tion on the surrounding environment. This information has meaningful observations which will be used to adapt the system according to its current status. The context term was defined by (2) as any information that can be used to charac- terize the situation of an entity. An entity is a person, place, or object that is considered to be relevant to the interaction between a user and an application, including the user and applications themselves. The contextual information available to a system or its components is modelled by a context model. In the case of service-oriented architecture (SOA), context models de- scribe contextual information available to individual ser- vices, which may extend a functional description of the services provided by usual means (e.g., their description in Web Services Description Language (WSDL)), and the actual state of service providers' environment affecting their availability (e.g., available resources or quality of network connections). In this way, context modelling makes ser- vices more accessible and discoverable. Moreover, sharing context models between different environments allows to es- tablish a common contextual base for system or component

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.

The Semantics of Web Services: An Examination in GIScience Applications

Web service is a technological solution for software interoperability that supports the seamless integration of diverse applications. In the vision of web service architecture, web services are described by the Web Service Description Language (WSDL), discovered through Universal Description, Discovery and Integration (UDDI) and communicate by the Simple Object Access Protocol (SOAP). Such a divination has never been fully accomplished yet. Although it was criticized that WSDL only has a syntactic definition of web services, but was not semantic, prior initiatives in semantic web services did not establish a correct methodology to resolve the problem. This paper examines the distinction and relationship between the syntactic and semantic definitions for web services that characterize different purposes in service computation. Further, this paper proposes that the semantics of web service are neutral and independent from the service interface definition, data types and platform. Such a conclusion can be a universal law in software engineering and service computing. Several use cases in the GIScience application are examined in this paper, while the formalization of geospatial services needs to be constructed by the GIScience community towards a comprehensive ontology of the conceptual definitions and relationships for geospatial computation. Advancements in semantic web services research will happen in domain science applications.

Revising WSDL Documents: Why and How, Part 2

In a previous article, the authors demonstrated that effectively discovering Web services helps developers avoid several common design errors in Web Service Description Language (WSDL) documents. Their proposed guidelines are unfortunately applicable only when publishers follow the top-down, or contract-first, method of building services, which isn't very popular due to its inherent costs. Here, they present an approach for preventing such errors when using a counterpart method--namely, bottom-up or code-first--and measure the approach's impact on service discovery. The rationale behind the study is that because code-first service interfaces are automatically generated by tools that--given a service implementation--deterministically map programming language constructs onto WSDL elements, the measurable properties of service implementations could influence resulting service interfaces.

A Web services vulnerability testing approach based on combinatorial mutation and SOAP message mutation

The testing of Web services is an essential aspect of their quality assurance, however, because this testing often involves injecting only one mutant at one time, some vulnerability faults cannot be detected. To address this, the current paper presents a set of mutation operators that can be combined and defines the corresponding combinatorial strategies based on data perturbation and combinatorial testing. Based on this, multiple mutants can be injected at one time to help uncover interactive faults. To improve testing efficiency and effectiveness, a combinatorial testing approach focusing on Web service vulnerability is proposed: Firstly, initial test data are generated with perturbation techniques based on Web Services Description Language documents and Simple Object Access Protocol messages. Then, a combinatorial testing cases generation (CTCG) algorithm is used to generate the final combinatorial test data according to the proposed strategies. Furthermore, for some special Web services in which there is only one parameter or one method in service interface, a fuzzy mutation approach algorithm, as a complementary approach to CTCG, is also proposed. Finally, some testing experiments are conducted to verify the effectiveness of the proposed approaches in an integrated testing platform. The experiments show that proposed approaches are both feasible and effective: They can find more vulnerability faults than the traditional approaches.

Optimized Reliable Mechanism for Improving Web Service Using WDDX and XML

Web service is reliable mechanisms for ensuring interoperabilitybetween one or more systemfor reliable data transaction. The transaction in web servicesdone using interfaceand such interface accomplished using Web service description language (WSDL). Interactions between one or more system in web services were done using the XML services. In this paper we have proposed Web service architecture to improve its efficiency with consistent interaction between systems using WDDX concept. WDDX does reliable web services using XML script for identifying system response for data transaction. We demonstrated our work with 100 system nodes subscribed to our own deployable web server using our proposed architecture with consecutive updates by both the systems to ensure high standards of data reliability. We have also measured the reliable data standards with error notification for identifying system behavior using parallel updates between sender and receiver systems as reliability measures. Our belief is that such an approach will provide efficient data transaction.

Information and knowledge management in online rich presence services

Nowadays many information technology services are moving towards online via ubiquitous networks, computing and information at unlimited speed anytime and anywhere with different kinds of technical platforms, especially in Web 2.0. In general, presence information expresses user willingness and ability to communicate with other users across a set of services for real-time communications. Web 2.0 uses the Web as a platform for embracing the interconnectivity and interactivity of Web-delivered content among different online users and communities, which have recently been assumed by the technology of services computing such as Web services. Web services are based on a set of XML standards such as Universal Description, Discovery and Integration (UDDI), Web Services Description Language (WSDL), Simple Object Access Protocol (SOAP), Business Process Execution Language for Web Services (BPEL4WS), and etc. The rapid development of Web 2.0 for massive social network collaboration facilitates the “rich presence services” to expose information and knowledge gathered through online social networks which assists intelligent decision making and analysis. Rich presence is described as an enhanced form of presence awareness in which a service can observe other online service/user attributes, such as personal identifiable information, location, time, behavior, movement, type-of-software, type-of-device, and type-of-network. The use of Web 2.0 technologies may generate both user-generated content as well as contextual information about users, for example, their current location and availability. Rich presence also refers to the aggregation of this information that makes presence attributed to consenting services available for use by other services/users. This result generates a consolidation of virtual, physical, and online services into a single richpresence platform based on content-based publish/subscribe services for efficient filtering and dissemination of presence information. Online rich presence services divulge only the availability of other services. In this context, knowledge management comprises a range of strategies and practices used in an online rich presence service to create, manage, coordinate, distribute, and enable adoption of information. Such information comprises knowledge, either embedded in services or embedded in business processes, focuses on organizational quality of services (QoS) objectives such as performance, and competitiveness. Therefore, this special issue aims to examine the information and knowledge management model in this emerging context for the next generation applications. All the 8 papers in this issue will have deep research results to report the advance of online rich presence services such as information discovery, knowledge management, recommendation and collaborative filtering, services compositions, supply chain management, trust framework, grid and cloud computing. In the first paper “Feasilibility and A Case Study on Content Optimization Services on Cloud” (Wong 2013), Wong focuses on content optimization services that modify and reorganize content to reduce the size of content and enhance the performance of processing on the content. Wong presents the economics related to these services with practical considerations when these services are implemented on a cloud, which is typically perceived to be a more economical and scalable option compared to traditional dedicated servers. C. K. Fung Boeing Research and Technology, Seattle, WA, USA e-mail: casey.k.fung@boeing.com

Semantic Driven Web Service Discovery (SDWSD) System

Service discovery is one of most challenging issues now-adays because of the increasing number of services but a very few techniques are available for their efficient discovery. It is worthless if there are abundant services available but we cannot avail our desired services only because of the irrelevant discovery system. The semantic based service discovery is proposed to enhance the discovery of these elusive services. Web service standards, in their present format supports only keyword based search and many services which can fulfill the user’s requirements are not retrieved. Basic requirement for efficient service discovery is to extract the contextual information provided in the service description. In such situation, the optimal solution is obtained by introducing semantics in the present Web Service Description Language (WSDL).

Clustering Web services to facilitate service discovery

Clustering Web services would greatly boost the ability of Web service search engine to retrieve relevant services. The performance of traditional Web service description language (WSDL)-based Web service clustering is not satisfied, due to the singleness of data source. Recently, Web service search engines such as Seekda! allow users to manually annotate Web services using tags, which describe functions of Web services or provide additional contextual and semantical information. In this paper, we cluster Web services by utilizing both WSDL documents and tags. To handle the clustering performance limitation caused by uneven tag distribution and noisy tags, we propose a hybrid Web service tag recommendation strategy, named WSTRec, which employs tag co-occurrence, tag mining, and semantic relevance measurement for tag recommendation. Extensive experiments are conducted based on our real-world dataset, which consists of 15,968 Web services. The experimental results demonstrate the effectiveness of our proposed service clustering and tag recommendation strategies. Specifically, compared with traditional WSDL-based Web service clustering approaches, the proposed approach produces gains in both precision and recall for up to 14 % in most cases.

A Cross-Layer Security Scheme of Web-Services-Based Communications for IEEE 1451 Sensor and Actuator Networks

IEEE 1451 standard has been proposed to provide a common communication interface and transducer electric data sheet format for wired and wireless distributed applications in smart transducers (sensors and actuators). Currently, a unified Web service for IEEE 1451 smart transducers is a must. However, ensuring the security of web-services-based communications for IEEE 1451 smart transducers is an unsolved problem. In this paper, we proposed a cross-layer security mechanism that deals with the requirements of authentication, integrity, confidentiality, and availability across the communication process in IEEE 1451 smart transducers. The scheme contains three cross-layer components logically, including XML Encryption and Signature, SOAP Security Extension, and Web Services Description Language (WSDL) Security Checking. The former two components satisfy the requirements of confidentiality, availability, integrity, authentication, nonrepudiation, and freshness. The third component satisfies the requirement of availability, which can protect the system against denial-of-service (DoS) attack. The three cross-layer security components are integrated seamlessly in our scheme. To evaluate the overhead, we perform tests to evaluate the effect of message size on the performance of the access inquiry web service. The result supports the usefulness and feasibility of our scheme.

A Study on Knowledge Discovery of Relevant Web Services with Semantic and Syntactic approaches

Web mining is the application of data mining techniques to discover patterns from the Web. Web services defines set of standards like WSDL(Web Service Description Language), SOAP(Simple Object Access Protocol) and UDDI(Universal Description Discovery and Integration) to support service description, discovery and invocation in a uniform interchangeable format between heterogeneous applications. Due to huge number of Web services and short content of WSDL description, the identification of correct Web services becomes a time consuming process and retrieves a vast amount of irrelevant Web services. This emerges the need for the efficient Web service mining framework for Web service discovery. Discovery involves matching, assessment and selection. Various complex relationships may provide incompatibility in delivering and identifying efficient Web services. As a result the web service requester did not attain the exact useful services. A research has emerged to develop method to improve the accuracy of Web service discovery to match the best services. In the discovery of Web services there are two approaches are available namely Semantic based approach and Syntactic based approach. Semantic based approach gives high accuracy than Syntactic approach but it takes high processing time. Syntactic based approach has high flexibility. Thus, this paper presents a survey of semantic based and syntactic based approaches of Web service discovery system and it proposed a novel approach which has better accuracy and good flexibility than existing one. Finally, it compares the existing approaches in web service discovery.

Anti-pattern free code-first web services for state-of-the-art Java WSDL generation tools

Service-Oriented Computing (SOC) promotes structuring applications via coarse-grained, remote components called services. To materialise SOC, web services is the most common choice. A web service comprises an implementation and a description using the Web Services Description Language (WSDL). Web services are often built by first implementing their behaviour and then generating its WSDL document via automatic tools. However, bad design practices already present in a service implementation may end up affecting the quality of its WSDL document. For web services to be reusable, good WSDL designs are crucial. Previously, Mateos et al. show that there is a high correlation between Object-Oriented (OO) metrics from service implementations and the occurrences of ‘anti-patterns’ in WSDL documents. In this follow-up paper, these results are extended to all the existing WSDL generation tools. A detailed analysis of the impact of OO metric-driven code refactorings on the quality of WSDL documents is also reported.

Resource Service Access Mechanism for Service Robots

As the development of the network and distributed technology enhances, network resources around service robots are more and more. With their help, service robots can complete much more complex tasks. To solve the problem of coordination among heterogeneous robots and resources, Web services as a middleware is employed to generate both the skeleton and stub for robots to invoke services from any resources as a universal way. To make the service invocation more intelligent, the potential relationships between Ontology Web Language for Services (OWL-S) and Web Services Description Language (WSDL) are utilized to realize the automation on service invocation logics so that the robots can automatically generate messages of invoking service based on its understanding for service descriptions. Experimental results demonstrate that the methods are valid.

A Bilayer Resource Model for Cloud Manufacturing Services

Cloud Manufacturing and Cloud Service is currently one of the main directions of development in the manufacturing industry. Under the Cloud Manufacturing environment, the characteristics of publishing, updating, searching, and accessing manufacturing resources are massive, complex, heterogeneous, and so forth. A bilayer manufacturing resource model with separation of Cloud End and Cloud Manufacturing Platform is proposed in this paper. In Cloud End, manufacturing resources are divided into single resource and complex resource, and a basic data model of manufacturing resources oriented to enterprise interior is established to store the physical characteristics. In Cloud Manufacturing Platform, a resource service attribute model oriented to actual users is established to store the service characteristics. This model is described in detail and realized with stateful Web Service Description Language (WSDL) document. An example is provided for illustrating the implementation of the concept.

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.

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.