Catálogo de publicaciones - libros

Systems and infrastructures are currently being developed to support Web services. The main idea is to encapsulate an organization’s functionality within an appropriate interface and advertise it as Web services. While in some cases Web services may be utilized in an isolated form, it is normal to expect Web services to be integrated as part of Web processes. There is a growing consensus that Web services alone will not be sufficient to develop valuable Web processes due the degree of heterogeneity, autonomy, and distribution of the Web. Several researchers agree that it is essential for Web services to be machine understandable in order to support all the phases of the lifecycle of Web processes. This paper deals with two of the hottest R&D and technology areas currently associated with the Web — Web services and the Semantic Web. It presents how applying semantics to each of the steps in the Semantic Web Process lifecycle can help address critical issues in reuse, integration and scalability.

Since the new terms, “Semantic Web” and “Web services”, have been introduced, researchers have followed two different roads. Following one road, academia has focused on developing a new set of languages to enable the automation of Web services execution and integration based on the Semantic Web. On the other road, industry has taken the lead to propose and develop technologies and infrastructures to support Web services and Web processes without, until recently, paying much attention to semantics. It is fundamental to analyze the trend that is being followed with regard to the “Semantic Web” and “Web services”. Therefore, two important questions need to be answered: “do the approaches taken by academia and industry differ in how they add semantics to Web services?” and “are their efforts converging or diverging?” This paper, based on a panel discussion at an international conference on Web services, which consisted of members of both academia and industry, addresses precisely these two questions.

Semantic Web services approach is emerging as a promising technology for the effective automation of services development and interoperability by providing richer descriptions of service properties, capabilities and behavior in form of metadata. In this short paper, we discuss interoperability issues in semantic Web services.

Service interface description languages such as WSDL, and related standards, are evolving rapidly to provide a foundation for interoperation between Web services. At the same time, Semantic Web service technologies, such as the Ontology Web Language for Services (OWL-S), are developing the means by which services can be given richer semantic specifications. Richer semantics can enable fuller, more flexible automation of service provision and use, and support the construction of more powerful tools and methodologies. Both sets of technologies can benefit from complementary uses and cross-fertilization of ideas. This paper shows how to use OWL-S in conjunction with Web service standards, and explains and illustrates the value added by the semantics expressed in OWL-S.

In today’s Web, Web services are created and updated on the fly. It’s already beyond the human ability to analysis them and generate the composition plan manually. A number of approaches have been proposed to tackle that problem. Most of them are inspired by the researches in cross-enterprise workflow and AI planning. This paper gives an overview of recent research efforts of automatic Web service composition both from the workflow and AI planning research community.

Web services are in the midst of making the transition from being a promising technology to being widely used in the industry. However, most efforts to use Web services have been manual, thus slowing down the ever changing and dynamic businesses of today. In this paper, we contend that more expressive descriptions of Web services will lead to greater automation and thus provide more agility to businesses. We present the METEOR-S front-end tools for source code annotation and semantic Web service description generation. We also present WSDL-S, a language created for incorporating semantic descriptions in the industry wide accepted WSDL, by extending WSDL 2.0.

Industry and researchers acknowledge Web services as being the next generation of distributed computing. However, several issues especially the reliability aspect needs to be addressed before Web services can deliver its promise. Due to their heterogeneous, autonomous and long-lived nature, traditional ACID (Atomicity, Consistency, Integrity, Durability) based models are not sufficient for providing transactional guarantee to Web services compositions. To overcome this limitation, many extended transaction models have been proposed based on the concept of compensation. In this paper, we stress on the importance of two aspects, the Cost of Compensation and End User Involvement, which are missing from most of the transaction models proposed until now. We also show how industry standards like BPEL4WS, WS-Transaction can be augmented to facilitate the above aspects. Finally, we propose a simple classification towards describing compensating operations.

Semantic Web Services enable the dynamic discovery of services based on a formal, explicit specification of the requester needs. The actual Web Services that will be used to satisfy the requester’s goal are selected at run-time and, therefore, they are not known beforehand. As a consequence, determining whether the selected services can be trusted becomes an essential issue. In this paper, we propose the use of the Peertrust language to decide if trust can be established between the requester and the service provider. We add modelling elements to the Web Service Modeling Ontology (WSMO) in order to include trust information in the description of Semantic Web Services. In this scenario, we discuss different registry architectures and their implications for the matchmaking process. In addition, we present a matching algorithm for the trust policies introduced.

The increasing availability of web services demands for a discovery mechanism to find services that satisfy our requirement. UDDI provides a web wide registry of web services, but its lack of an explicit capability representation and its syntax based search provided produces results that are coarse in nature. We propose to base the discovery mechanism on OWL-S. OWL-S allows us to semantically describe web services in terms of capabilities offered and to perform logic inference to match the capabilities requested with the capabilities offered. We propose OWL-S/UDDI matchmaker that combines the better of two technologies. We also implemented and analyzed its performance.