IT Application Development with Web Services

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.

A Web service is a software system that supports interoperable application-to-application interactions over a network. Web services are based on a set of XML standards such as Universal Description, Discovery and Integration (UDDI), Web Services Description Language (WSDL), and Simple Object Access Protocol (SOAP). Recently, there have been increasing demands and discussions about Web services privacy technologies in the industry and research community. To enable privacy protection for Web service consumers across multiple domains and services, the World Wide Web Consortium (W3C) published a document called “Web Services Architecture (WSA) Requirements” that defines some fundamental privacy requirements for Web services. However, no comprehensive solutions to the various privacy issues have been so far defined. For these reasons, this chapter will focus on privacy technologies by first discussing the main privacy issues in WSA and related protocols. Then, this chapter illustrates the standardization efforts going on in the context of privacy for Web services and proposes different technical approaches to tackle the privacy issues.

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.

Today the term e-business is often used for describing attempts of using Internet for improving business efficiencies and introducing innovative new business models. Until recently, the major focus of e-business has been around replacing the traditional communication means such as telephone and fax by Internet-based electronic data interchange. The introduction of new standards such as XML (Extensible Markup Language), SOAP (Simple Object Access Protocol), and UDDI (Universal Description, Discovery, and Integration) opened new opportunities for dynamically integrating business processes across corporate boundaries on demand. This architecture is called Web Services, and being pursued by major software vendors such as IBM and Microsoft. Web Services can also be considered as a new component-based, distributed computing architecture. This paper discusses the background of this new trend and explains the individual technologies including XML, SOAP, and UDDI that comprise the basis of Web Services.

Service oriented architecture is a glue that allows web applications to work in collaboration. It has become a driving force for the service-oriented computing (SOC) paradigm. In heterogeneous environments the SOC paradigm uses web services as the basic building block to support low costs as well as easy and rapid composition of distributed applications. A web service exposes its interfaces using the Web Service Description Language (WSDL). A central repository called universal description, discovery and integration (UDDI) is used by service providers to publish and register their web services. UDDI registries are used by web service consumers to locate the web services they require and metadata associated with them. Manually analyzing WSDL documents is the best approach, but also most expensive. Work has been done on employing various approaches to automate the classification of web services. However, previous research has focused on using a single technique for classification. This research paper focuses on the classification of web services using a majority vote based classifier ensemble technique. The ensemble model overcomes the limitations of conventional techniques by employing the ensemble of three heterogeneous classifiers: Naive Bayes, decision tree (J48), and Support Vector Machines. We applied tenfold cross-validation to test the efficiency of the model on a publicly available dataset consisting of 3738 real world web services categorized into 5 fields, which yielded an average accuracy of 92 %. The high accuracy is owed to two main factors, i.e., enhanced pre-processing with focused feature selection, and majority based ensemble classification.

Web services via wireless technologies, mobile services (M-services), HTTP, and XML have become important for conducting business. W3C XML Protocol Working Group has been developing standard techniques such as Web Services
\nDescription Language (WSDL), simple object access protocol
\n(SOAP), universal description discovery and integration (UDDI). However, at this stage, there is no standard technique for access control in M-services.
\nThis paper describes a secure and flexible access control scheme and protocol for M-services based on role based access control (RBAC). The access control architecture involves a Trusted Credential Center (TCC), a Trusted Authentication and Registration Center (TARC) and a secure ticket based mechanism for service access. Users and service providers register with the TARC and are authenticated. Based on this, tickets are issued by the
\nTCC to users. Tickets carry authorization information needed
\nfor the requested services. In particular, we are able to specify access control polices based on roles. The protocols between the various entities in the model are protected using appropriate security mechanisms such as signatures which are used to verify correctness of the requested service, as well as to direct billing information to the appropriate user. Our architecture supports efficient
\nauthentication of users and service providers over different
\ndomains and provides a secure access model for services to users. Our model is also able to support anonymity of users. Only the TARC is able to identify misbehaving users. We believe that the proposed architecture forms a good basis for achieving a secure and flexible M-service system.

4 - Universal Description, Discovery, and Integration

Web services form the core of e-business and hence, have experienced a rapid development in the past few years. This has led to a demand for a discovery mechanism for web services. Discovery is the most important task in the web service model because web services are useless if they cannot be discovered. A large number of web service discovery systems have been developed. Universal Description, Discovery and Integration (UDDI) is a typical mechanism that stores indexes to web services but it does not support semantics. Semantic web service discovery systems that have been developed include systems that support matching web services using the same ontology, systems that support matching web services using different ontologies, and systems that support limitations of UDDI. This paper presents a survey of web service discovery systems, focusing on systems that support semantics. The paper also elaborates on open issues relating to such discovery systems.

Chapter 11 - Web Services

Softwareengineersareincreasinglyadoptingserviceorientedar-chitectures (SOAs) for the automation of business processes andthe integration of IT systems, both within and across organisa-tional boundaries. These service oriented architectures frequentlyrely on web service standards, such as the Web Service Descrip-tion Language (WSDL) [5] and the Simple Object Access Protocol(SOAP) [10] for the implementation of service invocations acrossmachine boundaries.The combination of several web services into a more complexweb service is a crucial building block for service oriented archi-tectures. Peltz refers to such compositions that integrate the in-vocation of two or more services into a more complex executableworkflow as web service orchestration and contrasts this with webservice choreography, which tracks message exchanges betweendifferent autonomous domains [13]. Web service orchestration isappealing as it facilitates compositionality and reuse of the compo-nents that implement these services without necessarily having todeploy these services locally.Web service orchestration is supported by the Business ProcessExecution Language for Web Services (BPEL) [1]. BPEL emergedthrough consolidation of earlier work on IBM’s Web Service FlowLanguage (WSFL) [11] and XLANG [14] developed by Microsoft.BPELwas proposedas astandardby Microsoft, IBM,Siebel, BEA

A web service is an interface of the software component that can be accessed by standard Internet protocols. The web service technology enables an application to application communication and interoperability. The increasing number of web service providers throughout the globe have produced numerous web services providing the same or similar functionality. This necessitates the use of tools and techniques to search the suitable services available over the Web. UDDI (universal description, discovery and integration) is the first initiative to find the suitable web services based on the requester's functional demands. However, the requester's requirements may also include non-functional aspects like quality of service (QoS). In this paper, the authors define a QoS model for QoS aware and business driven web service publishing and selection. The authors propose a QoS requirement format for the requesters, to specify their complex demands on QoS for the web service selection. The authors define a tree structure called quality constraint tree (QCT) to represent the requester's variety of requirements on QoS properties having varied preferences. The paper proposes a QoS broker based architecture for web service selection, which facilitates the requesters to specify their QoS requirements to select qualitatively optimal web service. A web service selection algorithm is presented, which ranks the functionally similar web services based on the degree of satisfaction of the requester's QoS requirements and preferences. The paper defines web service provider qualities to distinguish qualitatively competitive web services. The paper also presents the modelling and selection mechanism for the requester's alternative constraints defined on the QoS. The authors implement the QoS broker based system to prove the correctness of the proposed web service selection mechanism.

Web services are a technology that has gained enormous popularity in the industry over the past two years. Web services introduce a new paradigm in the field of distribute computing where the emphasis is on the protocol that’s used rather than how the technology is implemented. The main advantage Web services have over other technologies that support distributed computing is that Web services are based on open standards such as Extensible Markup Language (XML), Simple Object Access Protocol (SOAP), Web Services Description Language (WSDL), Hypertext Transfer Protocol (HTTP), and so on, and hence are widely accepted in the industry. More than any other distributed computing technologies in the past, Web services promote interoperability between heterogeneous and incompatible systems.

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.

Exchanging and sharing scientific results are essential for researchers in the field of computational modelling. BioModels.net defines agreed-upon standards for model curation. A fundamental one, MIRIAM (Minimum Information Requested in the Annotation of Models), standardises the annotation and curation process of quantitative models in biology. To support this standard, MIRIAM Resources maintains a set of standard data types for annotating models, and provides services for manipulating these annotations. Furthermore, BioModels.net creates controlled vocabularies, such as SBO (Systems Biology Ontology) which strictly indexes, defines and links terms used in Systems Biology. Finally, BioModels Database provides a free, centralised, publicly accessible database for storing, searching and retrieving curated and annotated computational models. Each resource provides a web interface to submit, search, retrieve and display its data. In addition, the BioModels.net team provides a set of Web Services which allows the community to programmatically access the resources. A user is then able to perform remote queries, such as retrieving a model and resolving all its MIRIAM Annotations, as well as getting the details about the associated SBO terms. These web services use established standards. Communications rely on SOAP (Simple Object Access Protocol) messages and the available queries are described in a WSDL (Web Services Description Language) file. Several libraries are provided in order to simplify the development of client software. BioModels.net Web Services make one step further for the researchers to simulate and understand the entirety of a biological system, by allowing them to retrieve biological models in their own tool, combine queries in workflows and efficiently analyse models.

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.