Chapter {5} - WSDL

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.

There are several tools and techniques developed over the past decade for detecting duplicated code in software. However, there exists a class of languages for which clone detection is ill-suited. We discovered one of these languages when we attempted to use clone detection to find similar web service operations in service descriptions written in the Web Service Description Language (WSDL). WSDL is structured in such a way that identifying units for comparison becomes a challenge. WSDL service descriptions contain specifications of one or more operations that are divided into pieces and intermingled throughout the description. In this paper, we describe a method of reorganizing them in order to leverage clone detection technology to identify similar services. We introduce the idea of contextual clones -- clones that can only be found by augmenting code fragments with related information referenced by the fragment to give it context. We demonstrate this idea for WSDL and propose other languages and situations for which contextual clones may be of interest.

Web Services Description Language (WSDL) allows a structured way to standardize the description of Web Services, exploiting XML for the exchange of structured information. Nevertheless XML supports little interoperability between services, expected when WSDL documents have to be combined. In this context, the Semantic Web has become a promising research field. Semantic Models (e.g. RDF or OWL) allow knowledge from many different sources to be easily combined so that unexpected data connections can be used. In this paper we provide a description of WSDL documents into a metamodel representation of Semantic Models. It allows interoperability at different levels of abstraction. A Datalog rule based system queries both service description and associated semantic annotations. Such system is built on top of traditional database technology to guarantee an efficient management of Semantic Web Services Descriptions. Finally we present experiments on a real dataset to test the feasibility of the modeling approach.

With web services growing and accumulating in application area, service discovery has become a hot issue for service composition and service management. Service clustering provides a promising way to split the whole searching space into small regions so as to minimize the discovery time effectively. However, semantic information is a critical element during the whole disposing process. Current industrialized Web Service Description Language (WSDL) does not contain enough information for service description. Therefore, a service clustering method has been proposed, which enhances original WSDL document with semantic information by means of Linked Open Data (LOD). Experiment based on real service data has been performed, and comparison with similar methods has also been provided to demonstrate the effectiveness of the method. It is shown that utilizing semantic information from LOD enhances the precision of service clustering. And it forms a sound base for further comprehensive processing with semantic information.

With advances in automatic position sensing and wireless connectivity, location-based services (LBS) are rapidly developing, particularly in fields of geographic, tourism and logistic information systems. Currently, Web service has been viewed as one of most significant innovations in business industry, and designed on demand to provide spatial related information for LBS consumption. However, the traditional Web Service Description Language (WSDL) cannot meet those requirements, as WSDL is not able to support semantic content and information. In recent years, Ontology came up with an effective approach to enhance service description, automated discovery, dynamic composition, enactment, and other tasks such as managing and using service-based systems. In this paper, we propose geographic ontology based on Geography Markup Language (GML) and extend OWL-S profile to form geographic profile. Web service, which is advertised on the basis of our GeoProfile, contains geographic information inherently.

With the increasing use of web and Service Oriented Systems, web-services have become a widely adopted technology. Web services repositories are growing fast, creating the need for advanced tools for organizing and indexing them. Clustering web services, usually represented by Web Service Description Language (WSDL) documents, enables the web service search engines and users to organize and process large web service repositories in groups with similar functionality and characteristics. In this paper, we propose a novel technique of clustering WSDL documents. The proposed method considers web services as categorical data and each service is described by a set of values extracted from the content and structure of its description file and as quality measure of clustering is defined the mutual information of the clusters and their values. We describe the way to represent web services as categorical data and how to cluster them by using LIMBO algorithm, minimizing at the same time the information loss in features values. In experimental evaluation, our approach outperforms in terms of F-Measure the approaches which use alternative similarity measures and methods for clustering WSDL documents.

Web service technologies are becoming increasingly important for integrating systems and services. There is much activity and interest around standardization and usage of Web service technologies. Contemporary Web services are described in the Web Service Description Language (WSDL). However, WSDL documents can be difficult to understand for service developers. This article recommends a model-driven process for Web service development combining the graphical modeling language UML with WSDL. The Unified Modeling Language (UML) is developed by Object Management Group. In the proposed process, Web service descriptions (in WDSL) are converted to UML; their UML models are integrated to form composite Web services; and then the new Web service descriptions are exported. The main contribution of this article is a “pure UML” modeling strategy supported by implementation of two-way conversion rules between the UML models and the WSDL documents.

GIS Web service turns out to be one of the new directions of the paradigm of GIS, due to the popular use of the Internet and the dramatic progress of telecommunications technology. However, focused on the description of the interface of functions by Web service description language (WSDL), the general Web service technologies are not sufficient to model GIS Web service with data-oriented characteristic, especially those data provider services and data transform services. In this paper, we propose geographic-Web service description language (abbr. G-WSDL) which enhances the ability of describing such data-driven services by extending the current WSDL with service metadata. Two application scenarios will be presented at last to show its strength in automatic GIS Web service discovery and dynamic services combination.

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.

With the advent of distributed technologies and related Integrated Development Environments (IDEs), business collaborations across the world irrespective of the platforms in which applications were built.The underlying technology is Web Services which is based on XML standard and the architecture is SOA (Service Oriented Architecture).Many SOA frameworks came in to existence.However, their primary focus is discovering, composition of services in order to make flexible service oriented distributed enterprise applications.Such systems without human expertise may be incomplete.To overcome this problem, this paper proposes techniques to collaborate services based software with human experts thus forming a knowledgeintensive and people centric web besides sharing and reusing software components in distributed environment.To achieve this, we propose a flexible and adaptive approach which facilitates software services and humans to collaborate using Web Services and its important standards like SOAP (Simple Object Access Protocol), WSDL (Web Services Description Language) and UDDI (Universal Description Discovery Integration).This kind of human centric enterprise web has far reaching implications and it can attract the human experts to participate in rendering their best possible services.Interaction monitoring techniques that are adaptive thus realizing standards based people-centric systems.

The development, registration, discovery, and invocation of quality Web services are vital for the successful implementation of applications using Web services. Considerable research focuses on quality for Web services. Unfortunately, current research on Quality of Service (QoS) for Web services is concentrated on service users and the implementation stage. This research highlights the importance of incorporating QoS at the design and development stages; the authors propose the introduction of QoS at the same time as functional requirements. However, Web Service Description Language (WSDL) describes the functional elements of a Web service, and QoS is significant for this description. Therefore, the authors propose an extension to the WSDL through a generic QoS metamodel, incorporating QoS specifications into the functionalities. This paper begins by defining the required QoS specifications for the development of quality Web services and explores the potential of the Unified Modeling Language as a technique and notation to specify QoS. To properly integrate QoS in the design, the authors propose extensions to the existing UML QoS profile. The paper concludes with the evaluation of the proposed framework and summarises its advantages.

In this chapter, we provide an overview of the Web services technology, together with the set of standard specifications for Web services transactions. The core components of the Web services technology include eXtensible Markup Language (XML), HyperText Transfer Protocol (HTTP), Simple Object Access Protocol (SOAP), and Web Services Description Language (WSDL). Both SOAP and WSDL are based on XML. All these protocols and languages have the characteristic of strong extensibility, which lays a solid foundation for the success of the Web services technology. Due to the extensibility design, the protocols specified in the Web services transactions standards can be plugged into the Web services core seamlessly to provide the additional coordination needed for business transactions. Furthermore, we point out the need to protect the business transactions from the hardware failures and malicious faults, and for more robust coordination for Web services transactions.

This paper describes the proposed smart transducer Web services (STWS) developed at the National Institute of Standards and Technology (NIST) based on the IEEE 1451.0 standard. The STWS are described in WSDL (Web service description language). A prototype system has been established to test the STWS. This prototype system consists of a service consumer, service provider (wireless network node), and wireless sensor node. The service consumer and provider can communicate with each other through SOAP (simple object access protocol) messages. The STWS were tested successfully through a case study of reading an IEEE 1451 TEDS (transducer electronic data sheet). The proposed STWS provide a standard way for IEEE 1451 applications to achieve interoperability with other sensor applications in WSDL. Hence it provides a foundation for STWS standardization.

Spatial Data Infrastructures often maintain directories of public geospatial Web Services built from Web services listed in their registries. However, registry data may be stale and incomplete because their maintenance depends on service owners. A solution is to back the registry with an active directory, or index, that lists Web services found by a Web crawler focused on geospatial Web services. The problem of the identification of the geospatial nature of a Web service appears when such crawler finds a service described in the Web Services Description Language (WSDL). This paper presents two components required to build an active directory: a crawler focused on Open Geospatial Consortium and WSDL-based Web services, and an unsupervised classifier of geospatial Web services described in WSDL.

chapter 3 - Web Services