A Personalized Approach for Web Service Discovery in Distributed Environments

Web services are meaningful only if potential users may find and execute them. Universal Description Discovery and Integration (UDDI) help businesses, organizations, and other Web Services providers to discover and reach to the service(s) by providing the URI of the WSDL file. However, it does not offer a mechanism to choose a Web service based on its quality. The standard also lacks of sufficient semantic description in the content of Web services, this lack makes it difficult to find and compose suitable Web services during analysis, search, and matching processes. In addition, a central UDDI suffers from one centralized point problem and the high cost of maintenance. To get around these problems, the authors propose in this paper a novel framework based on mobile agent and metadata catalogue for WS discovery. Our approach is based on user profile in order to discover appropriate WS, meeting customer requirements, in less time and taking into account the QoS properties.

Web services are meaningful only if potential users may find and execute them. Universal Description Discovery and Integration (UDDI) help businesses, organisations, and other web services providers to discover and reach to the service(s) by providing the URI of the WSDL file. However, it does not offer a mechanism to choose a web service based on its quality. The standard also lacks sufficient semantic description in the content of web services, this lack makes it difficult to find and compose suitable web services during analysis, search, and matching processes. In addition, a central UDDI suffers from one centralised point problem and the high cost of maintenance. To get around these problems, the authors propose in this paper a novel framework based on mobile agent, metadata catalogue and user profile for web services discovery in order to reduce the search space and increase the number of relevant services.

Currently, UDDI (Universal Description Discovery and Integration) is a standard for publishing and discovery of Web services. The UDDI search mechanism is based on functional properties and the consumer chooses a web service based on these properties. When functional properties are identical, additional distinguishing characteristics are needed to choose a service. Towards this, we propose to associate non functional properties, referred to as criteria, with a web service. A web service that has a list of criteria associated with it is termed as Decision Support Web Service (DSWS). In order to associate criteria, the UDDI is extended to X-UDDI which includes a new orange page containing the list of criteria and their description. We also add one more bag, criteria bag, which is used to define the attributes of the criteria. In order to publish and invoke a service on both, the functional properties and the criteria, we define new APIs.

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.

4 - Universal Description, Discovery, and Integration

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.

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.

The advent of Web Services (WS) has signaled a true revolution in the way service-oriented computing and remote procedure invocation over the Web are conducted. Web Services comprise of a set of loosely coupled specifications to coordinate process execution from distance, based on common and widely accepted Web protocols such as HTTP, FTP, and XML, and therefore, providing increased development flexibility. Since the WS Framework was built on top of those protocols, Web Services have been widely acclaimed by the Web development community and paradoxically; they have marked one of the few examples in the history of computer protocols where a global consensus has been reached. The Web Service framework consists of essentially three basic components: 1. The Web Service Description Language (WSDL), a language that allows formal functional characterization of the provided functionalities; 2. The Simple Object Access Protocol (simply SOAP from its version 1.2), a protocol that defines the format of the information interchange; and 3. The UDDI (Universal Description, Discovery and Integration) is a catalog of Web Service descriptions. All three of these components are specified using XML markup. The elegance of the WS architecture lies in the fact that every WS transaction is taking place over established Web protocols such as HTTP and FTP. As remarked in Ballinger (2003, p. 5): “A Web Service is an application logic that is accessible using Internet standards.” This very fact has accounted for the rapid and universal adoption of Web Services. This work is organized as follows: First, a review of underlying technologies and tools is presented. Consequently, existing techniques for design methodologies are described. Next, an overview of storage and retrieval techniques for Web Services is given followed by real-world applications of Web Services. We conclude with open issues and discussion.

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.

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.

To address the challenges of dynamic, distributed and collaborative Web Services (WS) testing, this paper proposes a trustworthy service broker architecture and a dependence-based progressive group testing technique. The new architecture extends the traditional Universal Description, Discovery and Integration (UDDI) service broker by introducing the check-in and check-out testing interfaces, which are associated with a set of automated tools. The design objectives of the trustworthy service broker are to perform rigorous testing and evaluation effectively and to ensure that only quality WS can be registered and released to the public. A group testing technique is applied to reduce the test cost by using a hierarchy of increasingly sophisticated test scripts, which progressively rules out low quality WS. WS are further ranked based on the group testing results using ranking criteria. Experiments show that this approach can effectively test and choose WS in an open environment and in reduced number of tests.

Web services are becoming an important enabler of the semantic Web. Besides the need for a rich description mechanism, Web service information should be made available in an accessible way for machine processing. In this paper, we propose a new P2P based approach for Web services discovery. Peers that store Web services information, such as data item descriptions, are efficiently located using a scalable and robust data indexing structure for peer-to-peer data networks, NIPPERS. We present a theoretical analysis which shows that the communication cost of the query and update operations scale double-logarithmically with the number of NIPPERS nodes. Furthermore, we show that the network is robust with respect to failures fulfilling quality of Web services requirements.

Web services discovery provided by the UDDI registries is relatively primitive. It does not take into account the continuous growth in the number of services on the Web. The UDDI standard has been proposed and used for Web service publication and discovery. However, it does not allow users to choose the best provider. It does not offer a mechanism to choose a Web service based on its quality. The standard also lacks of sufficient semantic description in the content of Web services, this lack makes it difficult to find and compose suitable Web services during analysis, search, and matching processes. In addition, a central UDDI suffers from one centralized point problem and the high cost of maintenance. To get around these problems, the authors propose in this paper a novel framework based on mobile agent and metadata catalogue for Web services discovery. Their approach is based on user profile in order to discover appropriate Web services, meeting customer requirements, in less time and taking into account the QoS properties.

Nowadays Internet becomes the most used tool for the ever increasing amount of various transactions between institutions, organizations and more generally between clients and providers. Conducted studies and experiments showed that it is more convenient to provide and achieve these transactions as web services (WS) to guarantee their flexibility and their reuse. So far these services and the corresponding providers' URLs are advertised on specific UDDIs (Universal Description, Discovery and Integration). As such, after finding the requested service any given client contacts the right provider to negotiate the service access procedure. These first contacts between clients and providers are usually and commonly not protected (Encrypted) yielding enough room for Hackers to intrude into these unprotected messages. In this paper, we propose a securing approach based on both the PKI infrastructure and some proposed improvements of the UDDI functioning in an attempt to provide adequate security for 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.